We categorized the participants as “never had a mammogram,” “off schedule,” or “on schedule for their 2 most recent mammograms.” (We refer to the groups as never had, off schedule, and on schedule.)
We followed the recommendations of BCBS of NC which specified mammography consistent with the NCI recommendation: every 1 to 2 years for women in their 40s and every year for women in their 50s.14 However, because many women are not screened exactly 12 months following their previous mammogram, we added a 3-month window to the intervals; thus, the window was 15 months for women in their 50s and 27 months for women in their 40s. These interval windows are consistent with those adopted by other investigators.10
Our on- and off-schedule classification algorithms allow for women in their early 50s who passed from the “every 1 to 2 years” to the “every year” guidelines between their most recent and previous mammograms and those in their 40s who had not yet had time for 2 mammograms based on their age and the recommendations. The classification of women by screening mammography history is presented in Table 1
Because NCI recommendations indicate a single mammogram for average-risk women younger than 42 years, we could not consider women younger than this to be off schedule, so we excluded them (n=198) from our analysis. Women who had 2 mammograms within 11 months (n=32) were also excluded, because it is likely they were on diagnostic rather than screening schedules. The final analysis was based on 1057 women.
Information From the Telephone Interviews. The sociodemographics included age, ethnic background, educational level, marital status, employment, and financial status.
Medical and family history included whether the woman ever had an abnormal mammogram, a biopsy, or a first-degree relative with breast cancer.
Provider-related measures assessed whether the woman had a regular physician and a provider recommendation for mammography and whether she discussed decisions with her care providers.
Breast cancer screening measures assessed mammography and clinical breast examinations (CBE) using questions asked by the Breast Cancer Screening Consortium of the NCI.15
Other health-related behaviors included when women had their most recent cervical screening, if they exercised regularly (if so, how often), whether they smoked (if so, how frequently), and whether they had thought about, had ever used, and were currently using hormonal replacement therapy (HRT).
Mammography knowledge, beliefs, and perceptions included whether mammograms are effective for reducing breast cancer deaths, how often a woman should be screened, and at what age a woman is more likely to develop breast cancer. In addition, women were asked whether they agreed, disagreed, or were undecided about 20 statements (11 pro and 9 con) about mammography screening consistent with the Transtheoretical model.16,17 The 11 pro and 9 con statements were used to compute pro and con scores, respectively. A high pro score indicates positive beliefs about mammography, while a high con score indicates negative beliefs. Previous research indicates that women who have more pros are more likely to get regular screening mammograms.
Risk perception measures assessed perceived absolute and comparative (self vs other) breast cancer risks. The absolute risk questions included: “How likely are you to get breast cancer in (a) the next 10 years and (b) your lifetime?” Responses were on a 5-point scale from “very unlikely” to “very likely.” For comparative risk the women were asked, “Compared with other women your age, how likely are you to get breast cancer in (a) the next 10 years and (b) your lifetime?” Responses were on a 5-point scale from “much below” to “much above average.”
Worry about breast cancer was measured for the next 10 years and a woman’s lifetime. Five responses ranged from not at all to very worried.
The women were also asked whether they felt ambivalent about getting a mammogram within their age-specific recommended time frames. The responses were agree, disagree, and undecided.
Statistical Analysis
We used the Pearson chi-square test to compare differences in the never-had, off-schedule, and on-schedule groups on provider-related information about mammography screening, women’s mammography knowledge, risk perceptions, worry about breast cancer, ambivalence, and other health-related behaviors. In addition, we used the F test to compare differences in perceived pro and con scales in the 3 groups. Because we were testing several hypotheses, all tests were performed using a 2-sided a=0.01.18
Because we were interested in identifying factors that are associated with repeat mammography use and because the proportional odds assumption was violated, women who never had a mammogram were excluded from the logistic regression analysis. The same results were observed when the never-had group was included with the off-schedule group (data not shown). In a logistic regression analysis modeling the probability of being off schedule, candidate variables were those that had a P value less than or equal to .20 in bivariate analyses Table 2