User login
METHODS: Our study was a randomized controlled trial of a prostate cancer screening decision-aid consisting of an illustrated pamphlet as opposed to a comparison intervention. We included 257 men aged 50 to 80 years who were receiving primary care at a Department of Veterans Affairs Hospital in Milwaukee, Wisconsin. The decision-aid provided quantitative outcomes of prostate cancer screening with DRE and PSA. We subsequently evaluated prostate cancer screening knowledge, beliefs, and test use.
RESULTS: The illustrated pamphlet decision-aid was effective in improving knowledge of prostate cancer screening tests: 95% of the experimental group were aware of the possibility of false-negative test results compared with 85% of the comparison group (P <.01). Ninety-one percent of the experimental group were aware of the possibility of a false-positive screening test result compared with 65% of the comparison group (P <.01). However, there was no difference in the use of prostate cancer screening between the experimental (82%) and comparison (84%) groups, (P >.05).
CONCLUSIONS: When used in a primary care setting, an illustrated pamphlet decision-aid was effective in increasing knowledge of prostate cancer screening tests but did not change the use of these tests.
The practice of prostate cancer screening with serum prostate-specific antigen (PSA) and digital rectal examination (DRE) continues to increase, despite ongoing debate in the medical community on the efficacy of screening in reducing prostate cancer mortality.1-5 Prostate cancer screening remains controversial because of concern that mass screening may lead to the detection and treatment of clinically insignificant lesions, exposing an asymptomatic population to significant morbidity.4
It is widely recommended that patients be well informed of potential risks and benefits before engaging in a prostate cancer screening program.2,6-10 The health risks of prostate cancer screening include those of the initial tests, indicated follow-up tests (transrectal ultrasound [TRUS] or rectal biopsy), and therapeutic interventions. For example, an asymptomatic patient who is given a diagnosis of early-stage prostate cancer as a result of screening and is treated with a radical prostatectomy may develop impotence as a complication of treatment. Such a patient would have significant morbidity despite the fact that his cancer may have remained clinically silent throughout his lifetime. Also, the survival benefits of early detection and treatment of prostate cancer are unproven. Thus, the decision regarding prostate cancer screening provides clinicians and patients with a dilemma that involves informed decision making and patient input.
Previous studies report mixed results of the effect of decision-aids on the use of prostate cancer screening tests.11-13 One study reported a decrease in the use of such tests after exposure to a decision-aid in a primary care setting but no effect in a free PSA clinic.11 A second study found decreased interest in PSA screening after exposure to a decision-aid but did not evaluate screening test use.12 Finally, a third study found no effect of a decision-aid intervention on the use of prostate cancer screening tests.13 There is a need for further data on the effect of theoretically based decision-aids on men’s decisions to undergo prostate cancer screening.
Methods
We conducted a randomized controlled trial to test the effect of a prostate cancer screening decision-aid-an illustrated pamphlet-on patients’ knowledge, beliefs, and subsequent use of PSA and DRE prostate cancer screening tests.
Study Protocol
We included men aged 50 to 80 years who had an outpatient encounter in the years 1990 to 1995 at the Clement J. Zablocki Veterans Affairs Medical Center (VAMC) in Milwaukee, Wisconsin. We excluded men who had a history of prostate or other cancer, a previous prostate ultrasound study or biopsy, cystoscopy, prior prostate surgery, active genitourinary symptoms, cognitive impairment (defined by a Mini-Mental State Examination score of 23 or less), an anticipated life expectancy of less than 2 years, or who were currently employed by the VAMC. Potential subjects were identified from a randomly generated computerized list of patients who had received care at the VAMC in the designated time period. Patients were mailed a letter describing the study and inviting those interested to call and be considered for enrollment. The study protocol was approved by the Institutional Review Board of the VAMC and the Medical College of Wisconsin, and we obtained informed consent from all study participants.
The study protocol required 2 visits to the VAMC. At the initial study visit, subjects were randomized and baseline knowledge and belief surveys were administered. Data were also obtained on comorbidity using the Charlson comorbidity index and on reading level using the Rapid Estimate of Adult Literacy (REALM) instrument.14,15 Subjects were then given the experimental or the comparison intervention, each consisting of a written pamphlet to read and review. A research assistant was present when the subject reviewed the pamphlet and was available to answer questions. Postintervention knowledge and belief surveys were administered at the end of the initial study visit. A follow-up visit was scheduled with the subject’s primary care physician or one of the research investigators (JV or MMS) approximately 2 weeks after the initial study visit. At the follow-up visit, the subject was asked if he wanted to undergo prostate cancer screening with a PSA and a DRE. If the subject asked for the physician’s opinion, a scripted response was provided. The response emphasized the tossup nature of the decision and encouraged the patient to make up his own mind about prostate cancer screening. Men with a PSA test result that was greater than or equal to 4.0 ng/dL or those whose DRE was abnormal (asymmetric, indurated, or with a nodule) were referred to a urology clinic for confirmatory testing by TRUS and prostate biopsy. The screening tests were offered to at no cost. At the time of the study, there was no formal recommendation at the clinical site on the use of PSA for prostate cancer screening.
Development of the Decision-Aid
We conducted 2 focus groups to develop the content of the decision-aid. The focus group participants were similar to the target population: veterans aged 50 to 80 years who were receiving primary care at the VAMC. The Health Belief Model was used as the theoretical framework from which to probe focus group members regarding their knowledge and beliefs about prostate cancer screening.16,17 We found that patients had a general awareness of the prevalence of prostate cancer but expressed significant knowledge deficits and misinformation about risk factors, symptoms, screening recommendations, risk and benefits, treatment options, and prognosis for prostate cancer. We designed the content of the decision-aid to address the deficits in knowledge most striking in the focus groups.
The decision-aid included quantitative information on the operating characteristics (sensitivity and specificity) of a combined screening strategy of DRE and PSA and a description of follow-up tests (TRUS and prostate biopsy). Interpretation of probability outcomes are subject to many biases, including framing and presentation effects.18-20 We tried to present prostate cancer screening outcomes in a balanced manner. The graphic design used to convey the sensitivity and specificity of a prostate cancer screening strategy consisted of human figure representations Figure 1. An illustration presented 100 male human figures. A subset of figures was highlighted to represent the frequency of abnormal screening test results (10/100), true-positive test results (3/100), false-positive test results (7/100), and false-negative test results (1/100). Although treatment was not the focus of the intervention, treatment efficacy is one element of the total risks and benefits associated with prostate cancer screening. In the framework of the Health Belief Model, perceptions of treatment efficacy may influence screening behavior. We included a statement on the uncertain efficacy of treatment of early-stage prostate cancer in the decision-aid intervention.
The comparison intervention consisted of a written pamphlet containing basic prostate cancer information (epidemiology, symptoms of prostate cancer, prostate cancer screening methods, and the potential benefits of screening) but excluding the quantitative and qualitative outcomes regarding risks and benefits of screening that were included in the decision-aid. The basic prostate cancer information was also included in the decision-aid. Pamphlets were printed in a 14-point font to facilitate reading for older subjects. The comparison and experimental pamphlets were 5 and 8 pages in length, respectively.
Outcome Assessments
We used a prostate cancer knowledge assessment survey to evaluate the following domains: risk factors and incidence of prostate cancer, clinical presentation of prostate cancer, test characteristics of the DRE and the PSA, confirmatory tests (TRUS and prostate biopsy), and the natural history of prostate cancer. A prostate cancer belief-assessment survey was used to evaluate subjects’ perceptions of available screening tests and their intended screening behavior. Domains in the belief assessment included the natural history of prostate cancer, intentions to use prostate cancer screening, intentions to follow the physician’s advice on screening, perceptions of test characteristics, and how well informed they felt about screening options. The knowledge and belief assessment surveys consisted of 18 and 10 closed-ended items, respectively. The items were pilot-tested with 30 subjects who had demographic characteristics similar to those of the study population, and the format of items was revised accordingly. Test-retest reliability of single questions for correct/incorrect responses on the knowledge assessment were between 0.56 and 1.00 (average=0.82).
Prostate cancer screening use was ascertained from the follow-up physician visit. Subjects were asked if they wanted to be screened for prostate cancer with DRE or PSA, or both DRE and PSA. If they responded affirmatively, they were given the screening test at that study visit. A subject was considered to have chosen prostate cancer screening if he answered yes to having both the DRE and the PSA and proceeded to have those tests. For patients who had no rectum because of previous gastrointestinal surgery (n=3), a completed PSA met criteria for having chosen prostate cancer screening.
Statistical Methods
The knowledge survey was analyzed as total correct score and individual questions. Total knowledge scores on postintervention assessments were compared between groups using a Wilcoxon-Mann-Whitney test. When comparing the preintervention and postintervention responses to individual knowledge questions, subjects were assigned to 1 of 4 categories: (a) change in response from incorrect to correct, (b) incorrect response on both the pretest and the posttest, (c) correct response on both pretest and posttest, or (d) change in response from correct to incorrect. We used a chi-square analysis to compare categories of pre-post response pairs between the experimental and comparison groups. Postintervention responses to belief assessment items and use of prostate cancer screening (as defined by having both a DRE and a PSA test) were compared between groups with a chi-square analysis. Our study had a power of 0.80 to determine a 15% difference in the proportion of patients deciding to have prostate cancer screening, assuming that the baseline level of screening in the population was 80% and using a 2-sided test with an a of 0.05.
Results
There were 3592 invitation letters mailed to potential subjects, of which 572 men responded. Of the respondents, 257 (44.9%) were enrolled in the study Figure 2. Reasons for exclusion were history of previous cancer (50), history of prostate or genitourinary disease (102), poor mental status (12), and being an active employee at the medical center (23). Reasons for not participating among eligible patients included: not interested in participating (52), no phone (13), distance or transportation problems (7), the patient felt that he was too ill (26), and miscellaneous reasons (30). Experimental and comparison groups were similar in age, racial distribution, comorbidity, and education Table 1.
Prostate Cancer Screening Knowledge
The knowledge questionnaire listed 18 items. The range of total correct responses on postintervention scores was 5 to 18. There was no difference at baseline in total knowledge scores between the experimental (mean=11.7, standard deviation [SD] =2.4) and comparison (mean=11.4, SD=2.4) groups (P=.32). On postintervention assessments, the experimental group had a higher total knowledge score (mean=15.0, SD=2.3) than the comparison group (mean=14.1, SD=2.7; P <.01). On the postintervention survey, the experimental group was more likely than the comparison group to be aware of the possibility of false-negative and false-positive screening test results and had better knowledge of the natural history of prostate cancer Table 2. When asked to identify the risk of a false-negative test result, the experimental group was more likely than the comparison group (70% vs 49%, P <.05), to correctly identify 1/100 as the frequency of false negative results.
Prostate Cancer Screening Beliefs
Beliefs regarding the performance of prostate cancer screening tests differed between the groups. Specifically, fewer men in the experimental group than in the comparison group believed that screening tests were infallible Table 3. At baseline 79% of the subjects felt that “most men can be cured” if prostate cancer is caught in the early stages and treatment is received. Fifty-six percent of the subjects believed that of those men who have prostate cancer, most died of something else; 35% believed that approximately half die of prostate cancer; and only 9% believed that most men die of their prostate cancer. After the intervention, subjects in the experimental group were more likely than those in the comparison group (67% vs 46%) to respond that most men with prostate cancer die of something else (P <.01).
At baseline, 84% and 87% of the total study cohort stated that they were very likely to have a PSA and DRE, respectively. Ninety-eight percent of the subjects stated that they would have screening for prostate cancer if their physician recommended it. Finally, at baseline 77% of the subjects felt well informed enough to make a decision about prostate cancer screening. Perceptions of being well informed increased to 93% after the intervention but with no difference between groups.
Prostate Cancer Screening Decisions
Eighty-two percent of the experimental group, compared with 84% of the comparison group underwent prostate cancer screening (P=.60). Subjects who chose not to be screened did not differ from screened subjects in age, race, comorbidity level, education, or postintervention prostate cancer screening knowledge. Of the 214 subjects who chose to be screened, 32 had abnormal test results: 15 subjects had a PSA greater than 4.0, and 18 subjects had an abnormal DRE (one subject had both an abnormal DRE and a high PSA). Of the 32 abnormal exams, 21 had a prostate biopsy, and 7 prostate cancers were diagnosed. Of the 11 subjects with a positive screen who did not proceed to biopsy, 1 subject with an elevated PSA deferred a prostate biopsy and subsequently developed metastatic colon cancer. A second subject with elevated PSA refused TRUS and biopsy and continues to be followed up clinically. Of the remaining 9 patients who did not have further testing, one subject refused biopsy and elected to be followed clinically. Eight subjects were evaluated by urology tests, and the recommendation was for clinical follow-up without TRUS or rectal biopsy.
Discussion
We report that a prostate cancer screening aid consisting of an illustrated pamphlet was effective in improving knowledge and changing beliefs about prostate cancer screening when tested in a randomized controlled trial. The visual display of quantitative information improved knowledge about screening outcomes, but this knowledge alone did not change prostate cancer screening test use.
Prostate cancer screening is a clinical decision for which the risks are difficult to balance, a type of decision referred to as a “tossup” dilemma.21,22 The Health Belief Model posits that a change in perceived risks and benefits of screening may affect the likelihood of the patient’s taking preventive action (undergoing prostate cancer screening).16,17 Decision-aids have improved knowledge regarding decision outcomes, reduced decision conflict, and encouraged patients to be more active in the decision-making process.11,13,23 A recent meta-analysis24 shows that although decision-aids have a consistent effect on improving knowledge, they are less likely to alter decisions about a health care intervention. Previous studies of prostate cancer screening decision-aids have provided conflicting results. In one clinical trial, 12% of a primary care practice group exposed to a shared decision-making videotape intervention had a PSA test at their next scheduled clinic visit, compared with 23% of a control group (P=.04). However, a different arm of the same study found no effect of the intervention on the high rates of prostate cancer screening tests in a free PSA screening clinic. In a second clinical trial, men exposed to a scripted informational intervention were significantly less interested in PSA screening than those in a control group,12,25 but the subsequent use of screening tests was not evaluated. A third clinical trial in Canadian men found that a prostate cancer screening informational intervention in a discussion format increased participation in the decision-making process and decreased decisional conflict but did not alter the subsequent use of prostate cancer screening tests.13
A distinctive feature of our study is the use of a written pamphlet (as opposed to a videotape or a verbal discussion) as the decision-aid modality. Written materials are a commonly used method of educational support26 and in some studies have been preferred by patients to audiotapes or interactive computer materials.27 Patients respond favorably to having written materials that can be taken home to discuss with family or friends.28 However, written materials lack the ability of videotapes or discs to present video and audio role models for the deliberative decision-making process.23,29-30 Future studies are needed to examine the efficacy of written versus audiovisual modalities in presenting clinical outcomes to patients.
Our study supports the use of visual displays of frequencies when presenting information to patients. Human figure representations were used to visually convey the incidence of prostate cancer and the frequency of false-positive and false-negative test results (Figure 1). This approach was successful in improving knowledge regarding test characteristics. The visual display of quantitative information is an area of inquiry with important applications for communication of outcomes to patients.31-35 Previous studies have found that presenting very small probabilities with the use of dot diagrams has influenced the patient’s willingness to take risks.36 More work is needed on how best to display quantitative information in medical settings.
Limitations
Our study had some limitations. First, results were subject to volunteer bias, since the recruitment strategy required that interested patients reply to a mailed study invitation letter. The low rate of participation is similar to that found in previous prostate cancer screening studies that recruited subjects using mailed letters.37 Second, the study protocol removed some of the barriers to prostate cancer screening in the usual care setting. Subjects were offered prostate cancer screening on-site at the time of the follow-up study visit and did not have to pay for screening or follow-up tests. These 2 limitations may bias the study toward higher baseline levels of screening but should not differentially affect the comparison or intervention group. Finally, the current study evaluates knowledge, beliefs, and the subsequent use of prostate cancer screening tests. Other relevant outcomes, including decisional conflict, satisfaction with the decision-making process, and persistence of decision choice, deserve study in future research.
Conclusions
It is increasingly recognized that an informed decision-making process is appropriate before the use of cancer screening tests, especially those that lack strong efficacy evidence from clinical studies.2,6-10 Screening interventions are done in a healthy population during routine office visits, when limited time is available for the physician-patient encounter, and must be feasible in a busy office setting. Ideally, a decision-aid would be self-administered with the option of a follow-up interaction with the physician or another health care provider. Several modes of providing information can be used in this way, including a pamphlet, videotape, or interactive video-disk format. The pamphlet in our study was produced at a low cost, used graphic designs to help convey quantitative information, and was available for patients to take home and review. Simple decision-aids remain a viable method of presenting of complex information for preventive interventions such as prostate cancer screening. Further study is needed to understand the most effective decision-aids.
Acknowledgments
Our research was supported by the Department of Veterans Affairs, Veterans Health Administration, Health Services Research and Development Service (project no. SDR 93-005). Dr Schapira is Director of General Internal Medicine Research at the Medical College of Wisconsin and the Clement Zablocki Veterans Affairs Medical Center in Milwaukee, Wisconsin.
1. AL, Miller BA, Albertsen PC, Dramer BS. The role of increasing detection in the rising incidence of prostate cancer. JAMA 1995;273:548-52.
2. College of Physicians. Screening for prostate cancer. Clinical guideline: part III. Ann Intern Med 1997;126:480-4.
3. CM, Barry MJ, Fleming C, Fahs MC, Mulley AG. Early detection of prostate cancer. Part II: estimating the risks, benefits, and costs. American College of Physicians. Ann Intern Med 1997;126:468-79.
4. MT, Wagner EH, Thompson RS. PSA screening: a public health dilemma. Annu Rev Public Health 1995;16:283-306.
5. Preventive Services Task Force. Screening for prostate cancer. In: Guide to clinical preventive services: report of the US Preventive Services Task Force. 2nd ed. Baltimore, Md: Williams & Wilkins; 1996;119-34.
6. LM. Prostate cancer screening: a place for informed consent? Hosp Pract 1994;29:11-2.
7. AM, Becker DM. Cancer screening and informed patient discussions: truth and consequences. Arch Intern Med 1996;156:1069-72.
8. AS. The mammography and prostate-specific antigen controversies: implications for patient-physician encounters and public policy. J Gen Intern Med 1995;10:266-70.
9. PJ, Hall DMB. Screening, ethics, and the law. BMJ 1992;305:267-8.
10. JM. Screening and informed consent. N Engl J Med 1993;328:438-40.
11. AB, Wennberg JE, Nease RF, Fowler FJ, Ding J, Hynes LM. The importance of patient preference in the decision to screen for prostate cancer. J Gen Intern Med 1996;11:342-9.
12. AMD, Nasser JF, Wolf AM, Schorling JB. The impact of informed consent on patient interest in prostate-specific antigen screening. Arch Intern Med 1996;156:1333-6.
13. BJ, Kirk P, Degner LF, Hassard TH. Information and patient participation in screening for prostate cancer. Patient Educ Couns 1999;37:255-63.
14. ME, Pompei P, Alex KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chron Dis 1987;40:373-83.
15. TC, Long SL, Jackson RH, et al. Rapid estimate of adult literacy in medicine: a shortened screening instrument. Fam Med 1993;25:391-5.
16. J, Buechner J, Denman Scott J, et al. A study guided by the Health Belief Model of the predictors of breast cancer screening of women ages 40 and older. Public Health Rep 1991;106:410-20.
17. RC, Liang J. the early detection of cancer in the primary care setting: factors associated with the acceptance and completion of recommended procedures. Prev Med 1987;16:739-51.
18. DJ, Baron JA, Johansen S, Wahrenberger JW, Ross JM. The framing effect of relative and absolute risk. J Gen Intern Med 1993;8:543-8.
19. B, Bostrom A, Quadrel MJ. Risk perception and communication. Annu Rev Public Health 1993;14:183-203.
20. BJ, Pauker SG, Sox HC, Twersky A. On the elicitation of p for alternative therapies. N Engl J Med 1982;306:1259-69.
21. A. Arguments about tossups. Letter. N Eng J Med 1997;337:638.-
22. SG, Kassierer JP. Contentious screening decisions: does the choice matter? N Eng J Med 1997;336:1243-4.
23. MM, Mead C, Nattinger AB. Enhanced decision-making: the use of a videotape decision-aid for patients with prostate cancer. Patient Educ Couns 1997;30:119-27.
24. AM, Rostrom A, Fiset V, et al. Decision aids for patients facing health treatment or screening decisions; systematic review. BMJ 1999;319:731-4.
25. AM, Schorling JB. P of elderly men for prostate-specific antigen screening and the impact of informed consent. J Gerontol 1998;53:M195-200.
26. SH, McPhee SJ. Healthcare professionals’ use of cancer-related patient education materials: a pilot study. J Cancer Educ 1993;843:6.
27. M, Leek C. Patient education needs: opinions of oncology nurses and their patients. Oncol Nurs Forum 1995;1:139-45.
28. C, Streater A, Darlene M. Functions and preferred methods of receiving information related to radiotherapy: perceptions of patients with cancer. Cancer Nurs 1995;18:374-84.
29. LA, DeVellis B, DeVillis RF. Effects of modeling on patient communication, satisfaction and knowledge. Med Care 1987;25:1044-56.
30. L, Joliss JG, DeLong ER, Peterson ED, Morris KG, Mark DB. Impact of an interactive video on decision making of patients with ischemic heart disease. J Gen Intern Med 1996;11:373-6.
31. ER. The visual display of quantitative information. Cheshire, Conn: Graphics Press; 1983.
32. ER. Envisioning information. Cheshire, Conn: Graphics Press; 1990.
33. G, Murray DJ. Cognition as intuitive statistics. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc; 1987.
34. DJ, Hickam DH. Interpretation of graphic data by patients in general medicine clinic. J Gen Intern Med 1990;5:402-5.
35. IM, Hollands JG. The visual communication of risk. JNCI Monographs 1999;25:149-63.
36. RM, Hammel B, Schimmel LE. Patient information processing and the decision to accept treatment. J Soc Behav Pers 1985;1:113-20.
37. F, Candas B, Dupont A, et al. Screening decreases prostate cancer death: first analysis of the 1988 Quebec prospective randomized controlled trial. Prostate 1999;38:83-91.
METHODS: Our study was a randomized controlled trial of a prostate cancer screening decision-aid consisting of an illustrated pamphlet as opposed to a comparison intervention. We included 257 men aged 50 to 80 years who were receiving primary care at a Department of Veterans Affairs Hospital in Milwaukee, Wisconsin. The decision-aid provided quantitative outcomes of prostate cancer screening with DRE and PSA. We subsequently evaluated prostate cancer screening knowledge, beliefs, and test use.
RESULTS: The illustrated pamphlet decision-aid was effective in improving knowledge of prostate cancer screening tests: 95% of the experimental group were aware of the possibility of false-negative test results compared with 85% of the comparison group (P <.01). Ninety-one percent of the experimental group were aware of the possibility of a false-positive screening test result compared with 65% of the comparison group (P <.01). However, there was no difference in the use of prostate cancer screening between the experimental (82%) and comparison (84%) groups, (P >.05).
CONCLUSIONS: When used in a primary care setting, an illustrated pamphlet decision-aid was effective in increasing knowledge of prostate cancer screening tests but did not change the use of these tests.
The practice of prostate cancer screening with serum prostate-specific antigen (PSA) and digital rectal examination (DRE) continues to increase, despite ongoing debate in the medical community on the efficacy of screening in reducing prostate cancer mortality.1-5 Prostate cancer screening remains controversial because of concern that mass screening may lead to the detection and treatment of clinically insignificant lesions, exposing an asymptomatic population to significant morbidity.4
It is widely recommended that patients be well informed of potential risks and benefits before engaging in a prostate cancer screening program.2,6-10 The health risks of prostate cancer screening include those of the initial tests, indicated follow-up tests (transrectal ultrasound [TRUS] or rectal biopsy), and therapeutic interventions. For example, an asymptomatic patient who is given a diagnosis of early-stage prostate cancer as a result of screening and is treated with a radical prostatectomy may develop impotence as a complication of treatment. Such a patient would have significant morbidity despite the fact that his cancer may have remained clinically silent throughout his lifetime. Also, the survival benefits of early detection and treatment of prostate cancer are unproven. Thus, the decision regarding prostate cancer screening provides clinicians and patients with a dilemma that involves informed decision making and patient input.
Previous studies report mixed results of the effect of decision-aids on the use of prostate cancer screening tests.11-13 One study reported a decrease in the use of such tests after exposure to a decision-aid in a primary care setting but no effect in a free PSA clinic.11 A second study found decreased interest in PSA screening after exposure to a decision-aid but did not evaluate screening test use.12 Finally, a third study found no effect of a decision-aid intervention on the use of prostate cancer screening tests.13 There is a need for further data on the effect of theoretically based decision-aids on men’s decisions to undergo prostate cancer screening.
Methods
We conducted a randomized controlled trial to test the effect of a prostate cancer screening decision-aid-an illustrated pamphlet-on patients’ knowledge, beliefs, and subsequent use of PSA and DRE prostate cancer screening tests.
Study Protocol
We included men aged 50 to 80 years who had an outpatient encounter in the years 1990 to 1995 at the Clement J. Zablocki Veterans Affairs Medical Center (VAMC) in Milwaukee, Wisconsin. We excluded men who had a history of prostate or other cancer, a previous prostate ultrasound study or biopsy, cystoscopy, prior prostate surgery, active genitourinary symptoms, cognitive impairment (defined by a Mini-Mental State Examination score of 23 or less), an anticipated life expectancy of less than 2 years, or who were currently employed by the VAMC. Potential subjects were identified from a randomly generated computerized list of patients who had received care at the VAMC in the designated time period. Patients were mailed a letter describing the study and inviting those interested to call and be considered for enrollment. The study protocol was approved by the Institutional Review Board of the VAMC and the Medical College of Wisconsin, and we obtained informed consent from all study participants.
The study protocol required 2 visits to the VAMC. At the initial study visit, subjects were randomized and baseline knowledge and belief surveys were administered. Data were also obtained on comorbidity using the Charlson comorbidity index and on reading level using the Rapid Estimate of Adult Literacy (REALM) instrument.14,15 Subjects were then given the experimental or the comparison intervention, each consisting of a written pamphlet to read and review. A research assistant was present when the subject reviewed the pamphlet and was available to answer questions. Postintervention knowledge and belief surveys were administered at the end of the initial study visit. A follow-up visit was scheduled with the subject’s primary care physician or one of the research investigators (JV or MMS) approximately 2 weeks after the initial study visit. At the follow-up visit, the subject was asked if he wanted to undergo prostate cancer screening with a PSA and a DRE. If the subject asked for the physician’s opinion, a scripted response was provided. The response emphasized the tossup nature of the decision and encouraged the patient to make up his own mind about prostate cancer screening. Men with a PSA test result that was greater than or equal to 4.0 ng/dL or those whose DRE was abnormal (asymmetric, indurated, or with a nodule) were referred to a urology clinic for confirmatory testing by TRUS and prostate biopsy. The screening tests were offered to at no cost. At the time of the study, there was no formal recommendation at the clinical site on the use of PSA for prostate cancer screening.
Development of the Decision-Aid
We conducted 2 focus groups to develop the content of the decision-aid. The focus group participants were similar to the target population: veterans aged 50 to 80 years who were receiving primary care at the VAMC. The Health Belief Model was used as the theoretical framework from which to probe focus group members regarding their knowledge and beliefs about prostate cancer screening.16,17 We found that patients had a general awareness of the prevalence of prostate cancer but expressed significant knowledge deficits and misinformation about risk factors, symptoms, screening recommendations, risk and benefits, treatment options, and prognosis for prostate cancer. We designed the content of the decision-aid to address the deficits in knowledge most striking in the focus groups.
The decision-aid included quantitative information on the operating characteristics (sensitivity and specificity) of a combined screening strategy of DRE and PSA and a description of follow-up tests (TRUS and prostate biopsy). Interpretation of probability outcomes are subject to many biases, including framing and presentation effects.18-20 We tried to present prostate cancer screening outcomes in a balanced manner. The graphic design used to convey the sensitivity and specificity of a prostate cancer screening strategy consisted of human figure representations Figure 1. An illustration presented 100 male human figures. A subset of figures was highlighted to represent the frequency of abnormal screening test results (10/100), true-positive test results (3/100), false-positive test results (7/100), and false-negative test results (1/100). Although treatment was not the focus of the intervention, treatment efficacy is one element of the total risks and benefits associated with prostate cancer screening. In the framework of the Health Belief Model, perceptions of treatment efficacy may influence screening behavior. We included a statement on the uncertain efficacy of treatment of early-stage prostate cancer in the decision-aid intervention.
The comparison intervention consisted of a written pamphlet containing basic prostate cancer information (epidemiology, symptoms of prostate cancer, prostate cancer screening methods, and the potential benefits of screening) but excluding the quantitative and qualitative outcomes regarding risks and benefits of screening that were included in the decision-aid. The basic prostate cancer information was also included in the decision-aid. Pamphlets were printed in a 14-point font to facilitate reading for older subjects. The comparison and experimental pamphlets were 5 and 8 pages in length, respectively.
Outcome Assessments
We used a prostate cancer knowledge assessment survey to evaluate the following domains: risk factors and incidence of prostate cancer, clinical presentation of prostate cancer, test characteristics of the DRE and the PSA, confirmatory tests (TRUS and prostate biopsy), and the natural history of prostate cancer. A prostate cancer belief-assessment survey was used to evaluate subjects’ perceptions of available screening tests and their intended screening behavior. Domains in the belief assessment included the natural history of prostate cancer, intentions to use prostate cancer screening, intentions to follow the physician’s advice on screening, perceptions of test characteristics, and how well informed they felt about screening options. The knowledge and belief assessment surveys consisted of 18 and 10 closed-ended items, respectively. The items were pilot-tested with 30 subjects who had demographic characteristics similar to those of the study population, and the format of items was revised accordingly. Test-retest reliability of single questions for correct/incorrect responses on the knowledge assessment were between 0.56 and 1.00 (average=0.82).
Prostate cancer screening use was ascertained from the follow-up physician visit. Subjects were asked if they wanted to be screened for prostate cancer with DRE or PSA, or both DRE and PSA. If they responded affirmatively, they were given the screening test at that study visit. A subject was considered to have chosen prostate cancer screening if he answered yes to having both the DRE and the PSA and proceeded to have those tests. For patients who had no rectum because of previous gastrointestinal surgery (n=3), a completed PSA met criteria for having chosen prostate cancer screening.
Statistical Methods
The knowledge survey was analyzed as total correct score and individual questions. Total knowledge scores on postintervention assessments were compared between groups using a Wilcoxon-Mann-Whitney test. When comparing the preintervention and postintervention responses to individual knowledge questions, subjects were assigned to 1 of 4 categories: (a) change in response from incorrect to correct, (b) incorrect response on both the pretest and the posttest, (c) correct response on both pretest and posttest, or (d) change in response from correct to incorrect. We used a chi-square analysis to compare categories of pre-post response pairs between the experimental and comparison groups. Postintervention responses to belief assessment items and use of prostate cancer screening (as defined by having both a DRE and a PSA test) were compared between groups with a chi-square analysis. Our study had a power of 0.80 to determine a 15% difference in the proportion of patients deciding to have prostate cancer screening, assuming that the baseline level of screening in the population was 80% and using a 2-sided test with an a of 0.05.
Results
There were 3592 invitation letters mailed to potential subjects, of which 572 men responded. Of the respondents, 257 (44.9%) were enrolled in the study Figure 2. Reasons for exclusion were history of previous cancer (50), history of prostate or genitourinary disease (102), poor mental status (12), and being an active employee at the medical center (23). Reasons for not participating among eligible patients included: not interested in participating (52), no phone (13), distance or transportation problems (7), the patient felt that he was too ill (26), and miscellaneous reasons (30). Experimental and comparison groups were similar in age, racial distribution, comorbidity, and education Table 1.
Prostate Cancer Screening Knowledge
The knowledge questionnaire listed 18 items. The range of total correct responses on postintervention scores was 5 to 18. There was no difference at baseline in total knowledge scores between the experimental (mean=11.7, standard deviation [SD] =2.4) and comparison (mean=11.4, SD=2.4) groups (P=.32). On postintervention assessments, the experimental group had a higher total knowledge score (mean=15.0, SD=2.3) than the comparison group (mean=14.1, SD=2.7; P <.01). On the postintervention survey, the experimental group was more likely than the comparison group to be aware of the possibility of false-negative and false-positive screening test results and had better knowledge of the natural history of prostate cancer Table 2. When asked to identify the risk of a false-negative test result, the experimental group was more likely than the comparison group (70% vs 49%, P <.05), to correctly identify 1/100 as the frequency of false negative results.
Prostate Cancer Screening Beliefs
Beliefs regarding the performance of prostate cancer screening tests differed between the groups. Specifically, fewer men in the experimental group than in the comparison group believed that screening tests were infallible Table 3. At baseline 79% of the subjects felt that “most men can be cured” if prostate cancer is caught in the early stages and treatment is received. Fifty-six percent of the subjects believed that of those men who have prostate cancer, most died of something else; 35% believed that approximately half die of prostate cancer; and only 9% believed that most men die of their prostate cancer. After the intervention, subjects in the experimental group were more likely than those in the comparison group (67% vs 46%) to respond that most men with prostate cancer die of something else (P <.01).
At baseline, 84% and 87% of the total study cohort stated that they were very likely to have a PSA and DRE, respectively. Ninety-eight percent of the subjects stated that they would have screening for prostate cancer if their physician recommended it. Finally, at baseline 77% of the subjects felt well informed enough to make a decision about prostate cancer screening. Perceptions of being well informed increased to 93% after the intervention but with no difference between groups.
Prostate Cancer Screening Decisions
Eighty-two percent of the experimental group, compared with 84% of the comparison group underwent prostate cancer screening (P=.60). Subjects who chose not to be screened did not differ from screened subjects in age, race, comorbidity level, education, or postintervention prostate cancer screening knowledge. Of the 214 subjects who chose to be screened, 32 had abnormal test results: 15 subjects had a PSA greater than 4.0, and 18 subjects had an abnormal DRE (one subject had both an abnormal DRE and a high PSA). Of the 32 abnormal exams, 21 had a prostate biopsy, and 7 prostate cancers were diagnosed. Of the 11 subjects with a positive screen who did not proceed to biopsy, 1 subject with an elevated PSA deferred a prostate biopsy and subsequently developed metastatic colon cancer. A second subject with elevated PSA refused TRUS and biopsy and continues to be followed up clinically. Of the remaining 9 patients who did not have further testing, one subject refused biopsy and elected to be followed clinically. Eight subjects were evaluated by urology tests, and the recommendation was for clinical follow-up without TRUS or rectal biopsy.
Discussion
We report that a prostate cancer screening aid consisting of an illustrated pamphlet was effective in improving knowledge and changing beliefs about prostate cancer screening when tested in a randomized controlled trial. The visual display of quantitative information improved knowledge about screening outcomes, but this knowledge alone did not change prostate cancer screening test use.
Prostate cancer screening is a clinical decision for which the risks are difficult to balance, a type of decision referred to as a “tossup” dilemma.21,22 The Health Belief Model posits that a change in perceived risks and benefits of screening may affect the likelihood of the patient’s taking preventive action (undergoing prostate cancer screening).16,17 Decision-aids have improved knowledge regarding decision outcomes, reduced decision conflict, and encouraged patients to be more active in the decision-making process.11,13,23 A recent meta-analysis24 shows that although decision-aids have a consistent effect on improving knowledge, they are less likely to alter decisions about a health care intervention. Previous studies of prostate cancer screening decision-aids have provided conflicting results. In one clinical trial, 12% of a primary care practice group exposed to a shared decision-making videotape intervention had a PSA test at their next scheduled clinic visit, compared with 23% of a control group (P=.04). However, a different arm of the same study found no effect of the intervention on the high rates of prostate cancer screening tests in a free PSA screening clinic. In a second clinical trial, men exposed to a scripted informational intervention were significantly less interested in PSA screening than those in a control group,12,25 but the subsequent use of screening tests was not evaluated. A third clinical trial in Canadian men found that a prostate cancer screening informational intervention in a discussion format increased participation in the decision-making process and decreased decisional conflict but did not alter the subsequent use of prostate cancer screening tests.13
A distinctive feature of our study is the use of a written pamphlet (as opposed to a videotape or a verbal discussion) as the decision-aid modality. Written materials are a commonly used method of educational support26 and in some studies have been preferred by patients to audiotapes or interactive computer materials.27 Patients respond favorably to having written materials that can be taken home to discuss with family or friends.28 However, written materials lack the ability of videotapes or discs to present video and audio role models for the deliberative decision-making process.23,29-30 Future studies are needed to examine the efficacy of written versus audiovisual modalities in presenting clinical outcomes to patients.
Our study supports the use of visual displays of frequencies when presenting information to patients. Human figure representations were used to visually convey the incidence of prostate cancer and the frequency of false-positive and false-negative test results (Figure 1). This approach was successful in improving knowledge regarding test characteristics. The visual display of quantitative information is an area of inquiry with important applications for communication of outcomes to patients.31-35 Previous studies have found that presenting very small probabilities with the use of dot diagrams has influenced the patient’s willingness to take risks.36 More work is needed on how best to display quantitative information in medical settings.
Limitations
Our study had some limitations. First, results were subject to volunteer bias, since the recruitment strategy required that interested patients reply to a mailed study invitation letter. The low rate of participation is similar to that found in previous prostate cancer screening studies that recruited subjects using mailed letters.37 Second, the study protocol removed some of the barriers to prostate cancer screening in the usual care setting. Subjects were offered prostate cancer screening on-site at the time of the follow-up study visit and did not have to pay for screening or follow-up tests. These 2 limitations may bias the study toward higher baseline levels of screening but should not differentially affect the comparison or intervention group. Finally, the current study evaluates knowledge, beliefs, and the subsequent use of prostate cancer screening tests. Other relevant outcomes, including decisional conflict, satisfaction with the decision-making process, and persistence of decision choice, deserve study in future research.
Conclusions
It is increasingly recognized that an informed decision-making process is appropriate before the use of cancer screening tests, especially those that lack strong efficacy evidence from clinical studies.2,6-10 Screening interventions are done in a healthy population during routine office visits, when limited time is available for the physician-patient encounter, and must be feasible in a busy office setting. Ideally, a decision-aid would be self-administered with the option of a follow-up interaction with the physician or another health care provider. Several modes of providing information can be used in this way, including a pamphlet, videotape, or interactive video-disk format. The pamphlet in our study was produced at a low cost, used graphic designs to help convey quantitative information, and was available for patients to take home and review. Simple decision-aids remain a viable method of presenting of complex information for preventive interventions such as prostate cancer screening. Further study is needed to understand the most effective decision-aids.
Acknowledgments
Our research was supported by the Department of Veterans Affairs, Veterans Health Administration, Health Services Research and Development Service (project no. SDR 93-005). Dr Schapira is Director of General Internal Medicine Research at the Medical College of Wisconsin and the Clement Zablocki Veterans Affairs Medical Center in Milwaukee, Wisconsin.
METHODS: Our study was a randomized controlled trial of a prostate cancer screening decision-aid consisting of an illustrated pamphlet as opposed to a comparison intervention. We included 257 men aged 50 to 80 years who were receiving primary care at a Department of Veterans Affairs Hospital in Milwaukee, Wisconsin. The decision-aid provided quantitative outcomes of prostate cancer screening with DRE and PSA. We subsequently evaluated prostate cancer screening knowledge, beliefs, and test use.
RESULTS: The illustrated pamphlet decision-aid was effective in improving knowledge of prostate cancer screening tests: 95% of the experimental group were aware of the possibility of false-negative test results compared with 85% of the comparison group (P <.01). Ninety-one percent of the experimental group were aware of the possibility of a false-positive screening test result compared with 65% of the comparison group (P <.01). However, there was no difference in the use of prostate cancer screening between the experimental (82%) and comparison (84%) groups, (P >.05).
CONCLUSIONS: When used in a primary care setting, an illustrated pamphlet decision-aid was effective in increasing knowledge of prostate cancer screening tests but did not change the use of these tests.
The practice of prostate cancer screening with serum prostate-specific antigen (PSA) and digital rectal examination (DRE) continues to increase, despite ongoing debate in the medical community on the efficacy of screening in reducing prostate cancer mortality.1-5 Prostate cancer screening remains controversial because of concern that mass screening may lead to the detection and treatment of clinically insignificant lesions, exposing an asymptomatic population to significant morbidity.4
It is widely recommended that patients be well informed of potential risks and benefits before engaging in a prostate cancer screening program.2,6-10 The health risks of prostate cancer screening include those of the initial tests, indicated follow-up tests (transrectal ultrasound [TRUS] or rectal biopsy), and therapeutic interventions. For example, an asymptomatic patient who is given a diagnosis of early-stage prostate cancer as a result of screening and is treated with a radical prostatectomy may develop impotence as a complication of treatment. Such a patient would have significant morbidity despite the fact that his cancer may have remained clinically silent throughout his lifetime. Also, the survival benefits of early detection and treatment of prostate cancer are unproven. Thus, the decision regarding prostate cancer screening provides clinicians and patients with a dilemma that involves informed decision making and patient input.
Previous studies report mixed results of the effect of decision-aids on the use of prostate cancer screening tests.11-13 One study reported a decrease in the use of such tests after exposure to a decision-aid in a primary care setting but no effect in a free PSA clinic.11 A second study found decreased interest in PSA screening after exposure to a decision-aid but did not evaluate screening test use.12 Finally, a third study found no effect of a decision-aid intervention on the use of prostate cancer screening tests.13 There is a need for further data on the effect of theoretically based decision-aids on men’s decisions to undergo prostate cancer screening.
Methods
We conducted a randomized controlled trial to test the effect of a prostate cancer screening decision-aid-an illustrated pamphlet-on patients’ knowledge, beliefs, and subsequent use of PSA and DRE prostate cancer screening tests.
Study Protocol
We included men aged 50 to 80 years who had an outpatient encounter in the years 1990 to 1995 at the Clement J. Zablocki Veterans Affairs Medical Center (VAMC) in Milwaukee, Wisconsin. We excluded men who had a history of prostate or other cancer, a previous prostate ultrasound study or biopsy, cystoscopy, prior prostate surgery, active genitourinary symptoms, cognitive impairment (defined by a Mini-Mental State Examination score of 23 or less), an anticipated life expectancy of less than 2 years, or who were currently employed by the VAMC. Potential subjects were identified from a randomly generated computerized list of patients who had received care at the VAMC in the designated time period. Patients were mailed a letter describing the study and inviting those interested to call and be considered for enrollment. The study protocol was approved by the Institutional Review Board of the VAMC and the Medical College of Wisconsin, and we obtained informed consent from all study participants.
The study protocol required 2 visits to the VAMC. At the initial study visit, subjects were randomized and baseline knowledge and belief surveys were administered. Data were also obtained on comorbidity using the Charlson comorbidity index and on reading level using the Rapid Estimate of Adult Literacy (REALM) instrument.14,15 Subjects were then given the experimental or the comparison intervention, each consisting of a written pamphlet to read and review. A research assistant was present when the subject reviewed the pamphlet and was available to answer questions. Postintervention knowledge and belief surveys were administered at the end of the initial study visit. A follow-up visit was scheduled with the subject’s primary care physician or one of the research investigators (JV or MMS) approximately 2 weeks after the initial study visit. At the follow-up visit, the subject was asked if he wanted to undergo prostate cancer screening with a PSA and a DRE. If the subject asked for the physician’s opinion, a scripted response was provided. The response emphasized the tossup nature of the decision and encouraged the patient to make up his own mind about prostate cancer screening. Men with a PSA test result that was greater than or equal to 4.0 ng/dL or those whose DRE was abnormal (asymmetric, indurated, or with a nodule) were referred to a urology clinic for confirmatory testing by TRUS and prostate biopsy. The screening tests were offered to at no cost. At the time of the study, there was no formal recommendation at the clinical site on the use of PSA for prostate cancer screening.
Development of the Decision-Aid
We conducted 2 focus groups to develop the content of the decision-aid. The focus group participants were similar to the target population: veterans aged 50 to 80 years who were receiving primary care at the VAMC. The Health Belief Model was used as the theoretical framework from which to probe focus group members regarding their knowledge and beliefs about prostate cancer screening.16,17 We found that patients had a general awareness of the prevalence of prostate cancer but expressed significant knowledge deficits and misinformation about risk factors, symptoms, screening recommendations, risk and benefits, treatment options, and prognosis for prostate cancer. We designed the content of the decision-aid to address the deficits in knowledge most striking in the focus groups.
The decision-aid included quantitative information on the operating characteristics (sensitivity and specificity) of a combined screening strategy of DRE and PSA and a description of follow-up tests (TRUS and prostate biopsy). Interpretation of probability outcomes are subject to many biases, including framing and presentation effects.18-20 We tried to present prostate cancer screening outcomes in a balanced manner. The graphic design used to convey the sensitivity and specificity of a prostate cancer screening strategy consisted of human figure representations Figure 1. An illustration presented 100 male human figures. A subset of figures was highlighted to represent the frequency of abnormal screening test results (10/100), true-positive test results (3/100), false-positive test results (7/100), and false-negative test results (1/100). Although treatment was not the focus of the intervention, treatment efficacy is one element of the total risks and benefits associated with prostate cancer screening. In the framework of the Health Belief Model, perceptions of treatment efficacy may influence screening behavior. We included a statement on the uncertain efficacy of treatment of early-stage prostate cancer in the decision-aid intervention.
The comparison intervention consisted of a written pamphlet containing basic prostate cancer information (epidemiology, symptoms of prostate cancer, prostate cancer screening methods, and the potential benefits of screening) but excluding the quantitative and qualitative outcomes regarding risks and benefits of screening that were included in the decision-aid. The basic prostate cancer information was also included in the decision-aid. Pamphlets were printed in a 14-point font to facilitate reading for older subjects. The comparison and experimental pamphlets were 5 and 8 pages in length, respectively.
Outcome Assessments
We used a prostate cancer knowledge assessment survey to evaluate the following domains: risk factors and incidence of prostate cancer, clinical presentation of prostate cancer, test characteristics of the DRE and the PSA, confirmatory tests (TRUS and prostate biopsy), and the natural history of prostate cancer. A prostate cancer belief-assessment survey was used to evaluate subjects’ perceptions of available screening tests and their intended screening behavior. Domains in the belief assessment included the natural history of prostate cancer, intentions to use prostate cancer screening, intentions to follow the physician’s advice on screening, perceptions of test characteristics, and how well informed they felt about screening options. The knowledge and belief assessment surveys consisted of 18 and 10 closed-ended items, respectively. The items were pilot-tested with 30 subjects who had demographic characteristics similar to those of the study population, and the format of items was revised accordingly. Test-retest reliability of single questions for correct/incorrect responses on the knowledge assessment were between 0.56 and 1.00 (average=0.82).
Prostate cancer screening use was ascertained from the follow-up physician visit. Subjects were asked if they wanted to be screened for prostate cancer with DRE or PSA, or both DRE and PSA. If they responded affirmatively, they were given the screening test at that study visit. A subject was considered to have chosen prostate cancer screening if he answered yes to having both the DRE and the PSA and proceeded to have those tests. For patients who had no rectum because of previous gastrointestinal surgery (n=3), a completed PSA met criteria for having chosen prostate cancer screening.
Statistical Methods
The knowledge survey was analyzed as total correct score and individual questions. Total knowledge scores on postintervention assessments were compared between groups using a Wilcoxon-Mann-Whitney test. When comparing the preintervention and postintervention responses to individual knowledge questions, subjects were assigned to 1 of 4 categories: (a) change in response from incorrect to correct, (b) incorrect response on both the pretest and the posttest, (c) correct response on both pretest and posttest, or (d) change in response from correct to incorrect. We used a chi-square analysis to compare categories of pre-post response pairs between the experimental and comparison groups. Postintervention responses to belief assessment items and use of prostate cancer screening (as defined by having both a DRE and a PSA test) were compared between groups with a chi-square analysis. Our study had a power of 0.80 to determine a 15% difference in the proportion of patients deciding to have prostate cancer screening, assuming that the baseline level of screening in the population was 80% and using a 2-sided test with an a of 0.05.
Results
There were 3592 invitation letters mailed to potential subjects, of which 572 men responded. Of the respondents, 257 (44.9%) were enrolled in the study Figure 2. Reasons for exclusion were history of previous cancer (50), history of prostate or genitourinary disease (102), poor mental status (12), and being an active employee at the medical center (23). Reasons for not participating among eligible patients included: not interested in participating (52), no phone (13), distance or transportation problems (7), the patient felt that he was too ill (26), and miscellaneous reasons (30). Experimental and comparison groups were similar in age, racial distribution, comorbidity, and education Table 1.
Prostate Cancer Screening Knowledge
The knowledge questionnaire listed 18 items. The range of total correct responses on postintervention scores was 5 to 18. There was no difference at baseline in total knowledge scores between the experimental (mean=11.7, standard deviation [SD] =2.4) and comparison (mean=11.4, SD=2.4) groups (P=.32). On postintervention assessments, the experimental group had a higher total knowledge score (mean=15.0, SD=2.3) than the comparison group (mean=14.1, SD=2.7; P <.01). On the postintervention survey, the experimental group was more likely than the comparison group to be aware of the possibility of false-negative and false-positive screening test results and had better knowledge of the natural history of prostate cancer Table 2. When asked to identify the risk of a false-negative test result, the experimental group was more likely than the comparison group (70% vs 49%, P <.05), to correctly identify 1/100 as the frequency of false negative results.
Prostate Cancer Screening Beliefs
Beliefs regarding the performance of prostate cancer screening tests differed between the groups. Specifically, fewer men in the experimental group than in the comparison group believed that screening tests were infallible Table 3. At baseline 79% of the subjects felt that “most men can be cured” if prostate cancer is caught in the early stages and treatment is received. Fifty-six percent of the subjects believed that of those men who have prostate cancer, most died of something else; 35% believed that approximately half die of prostate cancer; and only 9% believed that most men die of their prostate cancer. After the intervention, subjects in the experimental group were more likely than those in the comparison group (67% vs 46%) to respond that most men with prostate cancer die of something else (P <.01).
At baseline, 84% and 87% of the total study cohort stated that they were very likely to have a PSA and DRE, respectively. Ninety-eight percent of the subjects stated that they would have screening for prostate cancer if their physician recommended it. Finally, at baseline 77% of the subjects felt well informed enough to make a decision about prostate cancer screening. Perceptions of being well informed increased to 93% after the intervention but with no difference between groups.
Prostate Cancer Screening Decisions
Eighty-two percent of the experimental group, compared with 84% of the comparison group underwent prostate cancer screening (P=.60). Subjects who chose not to be screened did not differ from screened subjects in age, race, comorbidity level, education, or postintervention prostate cancer screening knowledge. Of the 214 subjects who chose to be screened, 32 had abnormal test results: 15 subjects had a PSA greater than 4.0, and 18 subjects had an abnormal DRE (one subject had both an abnormal DRE and a high PSA). Of the 32 abnormal exams, 21 had a prostate biopsy, and 7 prostate cancers were diagnosed. Of the 11 subjects with a positive screen who did not proceed to biopsy, 1 subject with an elevated PSA deferred a prostate biopsy and subsequently developed metastatic colon cancer. A second subject with elevated PSA refused TRUS and biopsy and continues to be followed up clinically. Of the remaining 9 patients who did not have further testing, one subject refused biopsy and elected to be followed clinically. Eight subjects were evaluated by urology tests, and the recommendation was for clinical follow-up without TRUS or rectal biopsy.
Discussion
We report that a prostate cancer screening aid consisting of an illustrated pamphlet was effective in improving knowledge and changing beliefs about prostate cancer screening when tested in a randomized controlled trial. The visual display of quantitative information improved knowledge about screening outcomes, but this knowledge alone did not change prostate cancer screening test use.
Prostate cancer screening is a clinical decision for which the risks are difficult to balance, a type of decision referred to as a “tossup” dilemma.21,22 The Health Belief Model posits that a change in perceived risks and benefits of screening may affect the likelihood of the patient’s taking preventive action (undergoing prostate cancer screening).16,17 Decision-aids have improved knowledge regarding decision outcomes, reduced decision conflict, and encouraged patients to be more active in the decision-making process.11,13,23 A recent meta-analysis24 shows that although decision-aids have a consistent effect on improving knowledge, they are less likely to alter decisions about a health care intervention. Previous studies of prostate cancer screening decision-aids have provided conflicting results. In one clinical trial, 12% of a primary care practice group exposed to a shared decision-making videotape intervention had a PSA test at their next scheduled clinic visit, compared with 23% of a control group (P=.04). However, a different arm of the same study found no effect of the intervention on the high rates of prostate cancer screening tests in a free PSA screening clinic. In a second clinical trial, men exposed to a scripted informational intervention were significantly less interested in PSA screening than those in a control group,12,25 but the subsequent use of screening tests was not evaluated. A third clinical trial in Canadian men found that a prostate cancer screening informational intervention in a discussion format increased participation in the decision-making process and decreased decisional conflict but did not alter the subsequent use of prostate cancer screening tests.13
A distinctive feature of our study is the use of a written pamphlet (as opposed to a videotape or a verbal discussion) as the decision-aid modality. Written materials are a commonly used method of educational support26 and in some studies have been preferred by patients to audiotapes or interactive computer materials.27 Patients respond favorably to having written materials that can be taken home to discuss with family or friends.28 However, written materials lack the ability of videotapes or discs to present video and audio role models for the deliberative decision-making process.23,29-30 Future studies are needed to examine the efficacy of written versus audiovisual modalities in presenting clinical outcomes to patients.
Our study supports the use of visual displays of frequencies when presenting information to patients. Human figure representations were used to visually convey the incidence of prostate cancer and the frequency of false-positive and false-negative test results (Figure 1). This approach was successful in improving knowledge regarding test characteristics. The visual display of quantitative information is an area of inquiry with important applications for communication of outcomes to patients.31-35 Previous studies have found that presenting very small probabilities with the use of dot diagrams has influenced the patient’s willingness to take risks.36 More work is needed on how best to display quantitative information in medical settings.
Limitations
Our study had some limitations. First, results were subject to volunteer bias, since the recruitment strategy required that interested patients reply to a mailed study invitation letter. The low rate of participation is similar to that found in previous prostate cancer screening studies that recruited subjects using mailed letters.37 Second, the study protocol removed some of the barriers to prostate cancer screening in the usual care setting. Subjects were offered prostate cancer screening on-site at the time of the follow-up study visit and did not have to pay for screening or follow-up tests. These 2 limitations may bias the study toward higher baseline levels of screening but should not differentially affect the comparison or intervention group. Finally, the current study evaluates knowledge, beliefs, and the subsequent use of prostate cancer screening tests. Other relevant outcomes, including decisional conflict, satisfaction with the decision-making process, and persistence of decision choice, deserve study in future research.
Conclusions
It is increasingly recognized that an informed decision-making process is appropriate before the use of cancer screening tests, especially those that lack strong efficacy evidence from clinical studies.2,6-10 Screening interventions are done in a healthy population during routine office visits, when limited time is available for the physician-patient encounter, and must be feasible in a busy office setting. Ideally, a decision-aid would be self-administered with the option of a follow-up interaction with the physician or another health care provider. Several modes of providing information can be used in this way, including a pamphlet, videotape, or interactive video-disk format. The pamphlet in our study was produced at a low cost, used graphic designs to help convey quantitative information, and was available for patients to take home and review. Simple decision-aids remain a viable method of presenting of complex information for preventive interventions such as prostate cancer screening. Further study is needed to understand the most effective decision-aids.
Acknowledgments
Our research was supported by the Department of Veterans Affairs, Veterans Health Administration, Health Services Research and Development Service (project no. SDR 93-005). Dr Schapira is Director of General Internal Medicine Research at the Medical College of Wisconsin and the Clement Zablocki Veterans Affairs Medical Center in Milwaukee, Wisconsin.
1. AL, Miller BA, Albertsen PC, Dramer BS. The role of increasing detection in the rising incidence of prostate cancer. JAMA 1995;273:548-52.
2. College of Physicians. Screening for prostate cancer. Clinical guideline: part III. Ann Intern Med 1997;126:480-4.
3. CM, Barry MJ, Fleming C, Fahs MC, Mulley AG. Early detection of prostate cancer. Part II: estimating the risks, benefits, and costs. American College of Physicians. Ann Intern Med 1997;126:468-79.
4. MT, Wagner EH, Thompson RS. PSA screening: a public health dilemma. Annu Rev Public Health 1995;16:283-306.
5. Preventive Services Task Force. Screening for prostate cancer. In: Guide to clinical preventive services: report of the US Preventive Services Task Force. 2nd ed. Baltimore, Md: Williams & Wilkins; 1996;119-34.
6. LM. Prostate cancer screening: a place for informed consent? Hosp Pract 1994;29:11-2.
7. AM, Becker DM. Cancer screening and informed patient discussions: truth and consequences. Arch Intern Med 1996;156:1069-72.
8. AS. The mammography and prostate-specific antigen controversies: implications for patient-physician encounters and public policy. J Gen Intern Med 1995;10:266-70.
9. PJ, Hall DMB. Screening, ethics, and the law. BMJ 1992;305:267-8.
10. JM. Screening and informed consent. N Engl J Med 1993;328:438-40.
11. AB, Wennberg JE, Nease RF, Fowler FJ, Ding J, Hynes LM. The importance of patient preference in the decision to screen for prostate cancer. J Gen Intern Med 1996;11:342-9.
12. AMD, Nasser JF, Wolf AM, Schorling JB. The impact of informed consent on patient interest in prostate-specific antigen screening. Arch Intern Med 1996;156:1333-6.
13. BJ, Kirk P, Degner LF, Hassard TH. Information and patient participation in screening for prostate cancer. Patient Educ Couns 1999;37:255-63.
14. ME, Pompei P, Alex KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chron Dis 1987;40:373-83.
15. TC, Long SL, Jackson RH, et al. Rapid estimate of adult literacy in medicine: a shortened screening instrument. Fam Med 1993;25:391-5.
16. J, Buechner J, Denman Scott J, et al. A study guided by the Health Belief Model of the predictors of breast cancer screening of women ages 40 and older. Public Health Rep 1991;106:410-20.
17. RC, Liang J. the early detection of cancer in the primary care setting: factors associated with the acceptance and completion of recommended procedures. Prev Med 1987;16:739-51.
18. DJ, Baron JA, Johansen S, Wahrenberger JW, Ross JM. The framing effect of relative and absolute risk. J Gen Intern Med 1993;8:543-8.
19. B, Bostrom A, Quadrel MJ. Risk perception and communication. Annu Rev Public Health 1993;14:183-203.
20. BJ, Pauker SG, Sox HC, Twersky A. On the elicitation of p for alternative therapies. N Engl J Med 1982;306:1259-69.
21. A. Arguments about tossups. Letter. N Eng J Med 1997;337:638.-
22. SG, Kassierer JP. Contentious screening decisions: does the choice matter? N Eng J Med 1997;336:1243-4.
23. MM, Mead C, Nattinger AB. Enhanced decision-making: the use of a videotape decision-aid for patients with prostate cancer. Patient Educ Couns 1997;30:119-27.
24. AM, Rostrom A, Fiset V, et al. Decision aids for patients facing health treatment or screening decisions; systematic review. BMJ 1999;319:731-4.
25. AM, Schorling JB. P of elderly men for prostate-specific antigen screening and the impact of informed consent. J Gerontol 1998;53:M195-200.
26. SH, McPhee SJ. Healthcare professionals’ use of cancer-related patient education materials: a pilot study. J Cancer Educ 1993;843:6.
27. M, Leek C. Patient education needs: opinions of oncology nurses and their patients. Oncol Nurs Forum 1995;1:139-45.
28. C, Streater A, Darlene M. Functions and preferred methods of receiving information related to radiotherapy: perceptions of patients with cancer. Cancer Nurs 1995;18:374-84.
29. LA, DeVellis B, DeVillis RF. Effects of modeling on patient communication, satisfaction and knowledge. Med Care 1987;25:1044-56.
30. L, Joliss JG, DeLong ER, Peterson ED, Morris KG, Mark DB. Impact of an interactive video on decision making of patients with ischemic heart disease. J Gen Intern Med 1996;11:373-6.
31. ER. The visual display of quantitative information. Cheshire, Conn: Graphics Press; 1983.
32. ER. Envisioning information. Cheshire, Conn: Graphics Press; 1990.
33. G, Murray DJ. Cognition as intuitive statistics. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc; 1987.
34. DJ, Hickam DH. Interpretation of graphic data by patients in general medicine clinic. J Gen Intern Med 1990;5:402-5.
35. IM, Hollands JG. The visual communication of risk. JNCI Monographs 1999;25:149-63.
36. RM, Hammel B, Schimmel LE. Patient information processing and the decision to accept treatment. J Soc Behav Pers 1985;1:113-20.
37. F, Candas B, Dupont A, et al. Screening decreases prostate cancer death: first analysis of the 1988 Quebec prospective randomized controlled trial. Prostate 1999;38:83-91.
1. AL, Miller BA, Albertsen PC, Dramer BS. The role of increasing detection in the rising incidence of prostate cancer. JAMA 1995;273:548-52.
2. College of Physicians. Screening for prostate cancer. Clinical guideline: part III. Ann Intern Med 1997;126:480-4.
3. CM, Barry MJ, Fleming C, Fahs MC, Mulley AG. Early detection of prostate cancer. Part II: estimating the risks, benefits, and costs. American College of Physicians. Ann Intern Med 1997;126:468-79.
4. MT, Wagner EH, Thompson RS. PSA screening: a public health dilemma. Annu Rev Public Health 1995;16:283-306.
5. Preventive Services Task Force. Screening for prostate cancer. In: Guide to clinical preventive services: report of the US Preventive Services Task Force. 2nd ed. Baltimore, Md: Williams & Wilkins; 1996;119-34.
6. LM. Prostate cancer screening: a place for informed consent? Hosp Pract 1994;29:11-2.
7. AM, Becker DM. Cancer screening and informed patient discussions: truth and consequences. Arch Intern Med 1996;156:1069-72.
8. AS. The mammography and prostate-specific antigen controversies: implications for patient-physician encounters and public policy. J Gen Intern Med 1995;10:266-70.
9. PJ, Hall DMB. Screening, ethics, and the law. BMJ 1992;305:267-8.
10. JM. Screening and informed consent. N Engl J Med 1993;328:438-40.
11. AB, Wennberg JE, Nease RF, Fowler FJ, Ding J, Hynes LM. The importance of patient preference in the decision to screen for prostate cancer. J Gen Intern Med 1996;11:342-9.
12. AMD, Nasser JF, Wolf AM, Schorling JB. The impact of informed consent on patient interest in prostate-specific antigen screening. Arch Intern Med 1996;156:1333-6.
13. BJ, Kirk P, Degner LF, Hassard TH. Information and patient participation in screening for prostate cancer. Patient Educ Couns 1999;37:255-63.
14. ME, Pompei P, Alex KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chron Dis 1987;40:373-83.
15. TC, Long SL, Jackson RH, et al. Rapid estimate of adult literacy in medicine: a shortened screening instrument. Fam Med 1993;25:391-5.
16. J, Buechner J, Denman Scott J, et al. A study guided by the Health Belief Model of the predictors of breast cancer screening of women ages 40 and older. Public Health Rep 1991;106:410-20.
17. RC, Liang J. the early detection of cancer in the primary care setting: factors associated with the acceptance and completion of recommended procedures. Prev Med 1987;16:739-51.
18. DJ, Baron JA, Johansen S, Wahrenberger JW, Ross JM. The framing effect of relative and absolute risk. J Gen Intern Med 1993;8:543-8.
19. B, Bostrom A, Quadrel MJ. Risk perception and communication. Annu Rev Public Health 1993;14:183-203.
20. BJ, Pauker SG, Sox HC, Twersky A. On the elicitation of p for alternative therapies. N Engl J Med 1982;306:1259-69.
21. A. Arguments about tossups. Letter. N Eng J Med 1997;337:638.-
22. SG, Kassierer JP. Contentious screening decisions: does the choice matter? N Eng J Med 1997;336:1243-4.
23. MM, Mead C, Nattinger AB. Enhanced decision-making: the use of a videotape decision-aid for patients with prostate cancer. Patient Educ Couns 1997;30:119-27.
24. AM, Rostrom A, Fiset V, et al. Decision aids for patients facing health treatment or screening decisions; systematic review. BMJ 1999;319:731-4.
25. AM, Schorling JB. P of elderly men for prostate-specific antigen screening and the impact of informed consent. J Gerontol 1998;53:M195-200.
26. SH, McPhee SJ. Healthcare professionals’ use of cancer-related patient education materials: a pilot study. J Cancer Educ 1993;843:6.
27. M, Leek C. Patient education needs: opinions of oncology nurses and their patients. Oncol Nurs Forum 1995;1:139-45.
28. C, Streater A, Darlene M. Functions and preferred methods of receiving information related to radiotherapy: perceptions of patients with cancer. Cancer Nurs 1995;18:374-84.
29. LA, DeVellis B, DeVillis RF. Effects of modeling on patient communication, satisfaction and knowledge. Med Care 1987;25:1044-56.
30. L, Joliss JG, DeLong ER, Peterson ED, Morris KG, Mark DB. Impact of an interactive video on decision making of patients with ischemic heart disease. J Gen Intern Med 1996;11:373-6.
31. ER. The visual display of quantitative information. Cheshire, Conn: Graphics Press; 1983.
32. ER. Envisioning information. Cheshire, Conn: Graphics Press; 1990.
33. G, Murray DJ. Cognition as intuitive statistics. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc; 1987.
34. DJ, Hickam DH. Interpretation of graphic data by patients in general medicine clinic. J Gen Intern Med 1990;5:402-5.
35. IM, Hollands JG. The visual communication of risk. JNCI Monographs 1999;25:149-63.
36. RM, Hammel B, Schimmel LE. Patient information processing and the decision to accept treatment. J Soc Behav Pers 1985;1:113-20.
37. F, Candas B, Dupont A, et al. Screening decreases prostate cancer death: first analysis of the 1988 Quebec prospective randomized controlled trial. Prostate 1999;38:83-91.