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Gender Differences in the Utilization of Health Care Services
METHODS: New adult patients (N = 509) were randomly assigned to primary care physicians at a university medical center. Their use of health care services and associated charges were monitored for 1 year of care. Self-reported health status was measured using the Medical Outcomes Study Short Form-36 (SF-36). We controlled for health status, sociodemographic information, and primary care physician specialty in the statistical analyses.
RESULTS: Women had significantly lower self-reported health status and lower mean education and income than men. Women had a significantly higher mean number of visits to their primary care clinic and diagnostic services than men. Mean charges for primary care, specialty care, emergency treatment, diagnostic services, and annual total charges were all significantly higher for women than men; however, there were no differences for mean hospitalizations or hospital charges. After controlling for health status, sociodemographics, and clinic assignment, women still had higher medical charges for all categories of charges except hospitalizations.
CONCLUSIONS: Women have higher medical care service utilization and higher associated charges than men. Although the appropriateness of these differences was not determined, these findings have implications for health care.
Studies have consistently shown that women use more health care services than men.1-4 Several explanations have been offered. These differences may be associated with reproductive biology and conditions specific to gender,3,5-6 higher rates of morbidity in women than in men,1-4 differences in health perceptions and the reporting of symptoms and illnesses,1-4 or a greater likelihood that women seek help for prevention and illness.1,2,4 Physician referral practice patterns may also partially explain the rates of specialty care and diagnostic testing. Men are referred to specialty care more often than women,7 and hospitalized men are more likely to be referred for invasive cardiac procedures than women.8-9
The authors of some previous studies describing gender differences in the use of health care services have examined large secondary data sets without incorporating important independent variables, such as sociodemographic information or patient health status.3-5 Other researchers have attempted to control for health status by including in the study population only those individuals rating their health as good or excellent.2 Still others have used limited health status measures that have not been tested for reliability and validity.1
Although there have been a number of studies demonstrating distinctive patterns in the use of health care by women, few have reported associated health care expenditure differences. A recent study from Canada (a country with a system of universal health insurance) presented data on the crude annual per capita use of health care resources for men and women in the province of Manitoba.5 Using administrative data from electronic records, the investigators concluded that expenditures for health care were similar for men and women. Unfortunately, data regarding individual health status, sociodemographics, or other possible confounders were unavailable.
The purpose of our study was to examine gender differences in the use of health care services and in the associated charges for 1 year of care. Since any cogent discussion of differential medical visit frequencies and charges requires controlling for sociodemographic and health status patient variables, these factors were incorporated. We chose an instrument widely used in health services research—the Medical Outcomes Study Short Form-36 (SF-36)—to measure self-reported health status. Also, because it has been demonstrated that medical specialty is associated with variations in resource utilization10 and that practice style differences between family physicians and general internists are associated with differential medical charges,11 our analyses also controlled for primary care physician specialty. We hypothesized that even after controlling for these factors women would have more medical care services use and higher charges than men.
Methods
Subjects
Our study population consisted of new patients requesting outpatient appointments at a university medical center. Of the first 956 nonpregnant adults having no preference for a specific physician or specialty, 821 (85%) agreed to participate. These patients were randomly assigned for primary care to either the family practice clinic or the general medicine clinic. Three hundred twelve (38%) of these patients were excluded from the study because they did not keep their appointment or could not be included for scheduling reasons. A total of 509 patients participated in the study, with no differential external health care utilization expected.
Procedures and Measures
We interviewed study participants before the initial visit with their primary care provider to collect sociodemographic data, and we used the SF-36 to determine self-reported health status. The SF-36 contains 8 scales: general health, physical function, physical role, mental role, social function, pain, energy, and mental health. Reliability and validity have been demonstrated for this questionnaire.12,13 Summary measures can be constructed for both physical and mental health status components.14
After a study period of 1 year, we contacted patients and asked them to complete exit interviews. A total of 417 (82%) returned follow-up questionnaires. Self-reported health status measures provided patient outcome data on changes in health status during the study period.
Medical care was provided by 26 family practice and 79 general internal medicine second- and third-year residents. Those 105 primary care physicians each saw an average of 4.8 patients (standard deviation = 4.6 patients).
Resource Use and Medical Charges
Medical center resource use for the 1 year of care was determined by review of the comprehensive unified medical record. Physician reviewers noted the number of primary care visits, specialty clinic visits, emergency department visits, hospitalizations, and laboratory, diagnostic, and radiological tests (diagnostic services). Medical charges for all these services were obtained from the institutional central billing unit used by both clinics. Charges, used as a proxy for medical costs, were assigned to 1 of 5 categories: primary care clinics, specialty care clinics, emergency departments, hospitals (including outpatient surgical), and diagnostic services. In addition, yearlong totals for the 5 types of charges were calculated for each patient.
Results
As shown in Table 1, the 509 study patients included 315 women (62%) and 194 men (38%). Mean age and ethnicity were not significantly different for the 2 genders. Women, however, had significantly lower mean education, income, and self-reported physical and mental health status as measured by the respective SF-36 components.
The use of health care services by men and women was compared with 2-tailed Student t tests Table 2. Women had a significantly higher mean number of visits to their primary care clinic (P = .0004) and a significantly higher mean number of diagnostic services ordered (P = .0005). There were no statistically significant gender differences in the mean number of specialty clinic visits, emergency department visits, or hospitalizations.
The mean and median annual per capita expenditures for the 5 categories of medical charges (and total charges) for women and men are displayed in Table 3. To reduce the influence of outliers, the natural logarithm of these charges (plus $10) was used to examine gender differences in medical care charges using 2-tailed Student t tests to compare the 5 categories of medical charges Table 4. Women had significantly higher primary care (P = .0010), specialty clinic (P = .0487), emergency department (P = .0065), diagnostic services (P = .0016), and total charges (P = .0037) than men. There was no significant difference in hospital charges.
Regression equations were then estimated to relate the logarithm of medical charges of all categories to gender, controlling for clinic assignment, self-reported physical and mental patient health status, age, education, and income Table 5. Clinic assignment was significantly related to primary care and emergency department charges. Approximately 17% of the variation in log-transformed total charges was explained by clinic assignment, physical and mental health status, age, education, income, and patient gender. Because the dependent variable is expressed in logs, exponentiation of the estimated coefficients for any of the indicator variables (for example, the coefficient 0.1468 for the variable “female” in the primary care equation) provides the percentage by which average charges for those patients having that characteristic exceed average charges for those who do not. Thus, women had 15.8% higher charges for primary care clinic visits than men. They also had 9.4% greater charges in specialty clinics, 9.6% higher charges for emergency department care, and 10.4% greater charges for diagnostic services. Overall, their charges exceeded those of men by a statistically and clinically significant 9.9%. Predictably, physical health status and age were significantly related to medical charges.
Following a year of care, we calculated change in self-reported health status (exit health status minus entry health status). There were no significant differences in change of physical or mental health status (P = .0651 and .3691, respectively) for women compared with men. The trend for women to report their physical health status as improved to a greater extent than men should be noted.
Discussion
Previous studies reporting that women use more medical services than men have suggested that this is due to gender differences in morbidity and self-reported health status.1-4,6 Indeed, women in our study reported both baseline physical and mental health status significantly lower than the men. We found the subsequent mean numbers of primary care visits and diagnostic services were significantly higher for women than for men. Primary care physicians may be more likely to order laboratory, radiologic, and other diagnostic tests for women who make more frequent visits and have continuing medical complaints. We did not, however, observe the higher referral rates to specialty care for men that others have found.7
Charges for primary care, specialty care, emergency treatment, diagnostic services, and yearlong total charges were all significantly higher for women. Although it is logical that the higher mean numbers of primary care visits and diagnostic tests for women would be associated with higher charges for these services, it was also observed that specialty care and emergency treatment charges were higher for women despite visit rates similar to those of men. The poorer health status of women may have led to more complicated and costlier care when they were seen in the specialty clinics or emergency department compared with men who had better baseline health. Both the mean number of hospitalizations and related hospital charges, however, were not different for men and women. This confirms the work of Verbrugge and Wingard,4 who also observed that although women use more outpatient services, they have similar or lower rates of hospitalization than men.
Regression equation analysis highlighted the importance of physical health status, age, and clinic assignment in the prediction of medical charges. Lower physical health status and advancing age both predicted higher medical charges. Clinic assignment was also found to be related to medical charges. As seen in our previous study,11 patients’ assignment to care by internists versus family physicians was associated with higher charges for primary care and emergency department care. Even after controlling for clinic assignment, health status, age, and other sociodemographic variables, women continued to be associated with higher medical charges for all categories of charges except hospitalizations. Higher health care utilization and associated charges did not lead to significantly better health outcomes for women.
The differences we found may result from patients’ health beliefs and help-seeking behavior. Women have been found to be more predisposed to report their health as poor.3 They also have a greater willingness and ability to take care of themselves when they are sick and to seek preventive care.4 Physicians, in turn, may respond to these attitudinal and behavioral characteristics in women by providing them with differential diagnosis and treatment.
The strengths of our study include the fact that we measured health status with a widely used instrument that allowed us to control for this important variable. We also controlled for sociodemographic variables and physician specialty to more accurately assess the influence of patient gender on health service utilization. In addition to information about utilization patterns, medical charge data were available to compare costs of care for men and women.
Limitations
There were a number of limitations which should also be noted. Our study was conducted at a university medical center with primary care resident physicians. These physicians-in-training may be more likely to differentially care for patients on the basis of patient gender. In addition, patients participating in the study had no preference for a specific physician or specialty. It may also be true that the study patients represent a different population than those cared for in the community. It was found, for example, that both the self-reported physical and mental health status scores for these study patients were lower than national means. Although we included only nonpregnant adults (not requiring obstetrical care) and controlled for health status, we did not attempt to control for differences in health care utilization associated with gender-specific problems. Also, we did not measure patient health attitudes, which may be an important factor in seeking and using health services.
Conclusions
Our hypothesis was confirmed: Women used more medical services and have higher outpatient expenditures than men, even when controlling for health status and other variables. We cannot judge the appropriateness of these gender differences in resource utilization. There was a trend, though not significant, for women to report a greater improvement in their physical health status than men. It is possible that these men underused health care resources and had unmet medical needs. Future studies examining differential health care utilization need to incorporate appropriate patient health outcome measures. This research has implications for health care organizations that seek to provide quality comprehensive care that is cost efficient for both men and women.
Acknowledgments
Our research was supported by the Agency for Health Care Policy and Research Grant R18 HS06167.
1. PD, Mechanic D, Greenley JR. Sex differences in medical care utilization: an empirical investigation. J Health Soc Behav 1982;23:106-19.
2. Hibbard JH, Pope CR. Gender roles, illness orientation and use of medical services. Soc Sci Med 1983;17:129-37.
3. Waldron I. Sex differences in illness incidence, prognosis and mortality: issues and evidence. Soc Sci Med 1983;17:1107-23.
4. Verbrugge LM, Wingard DL. Sex differentials in health and mortality. Women Health 1987;12:103-45.
5. Mustard CA, Kaufert P, Kozyrsky A, Mayer T. Sex differences in the use of health care services. N Engl J Med 1998;338:1678-83.
6. Gijsbers van Wijk CMT, Kolk AM, van den Bosch WJHM, van den Hoogen HJM. Male and female morbidity in general practice: the nature of sex differences. Soc Sci Med 1992;35:665-78.
7. Franks P, Clancy CM. Referrals of adult patients from primary care: demographic disparities and their relationship to HMO insurance. J Fam Pract 1997;45:47-53.
8. Ayanian JZ, Epstein AM. Differences in the use of procedures between women and men hospitalized for coronary heart disease. N Engl J Med 1991;325:221-5.
9. Giles WH, Anda RF, Casper ML, Escobedo LG, Taylor HA. Race and sex differences in rates of invasive cardiac procedures in U.S. hospitals: data from the national hospital discharge survey. Arch Intern Med 1995;155:318-24.
10. S, Nelson EC, Zubkoff M, et al. Variations in resource utilization among medical specialties and systems of care. JAMA 1992;267:1624-30.
11. KD, Helms LJ, Azari R, Callahan EJ, Robbins JA, Miller J. Differences between family physicians’ and general internists’ medical charges. Med Care 1999;37:78-82.
12. CA, Ware JE, Lu JFR, Sherbourne CD. The MOS 36-item short-form health survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care 1994;32:40-66.
13. CA, Ware JE, Raczek AE. The MOS 36-item short-form health survey (SF-36): II. Psychometric and clinical tests of validity in measuring physical and mental health constructs. Med Care 1993;31:247-63.
14. JE, Kosinski M, Keller SD. SF-36 physical and mental health summary scales: a user’s manual. Boston, Mass: Nimrod Press, 1994.
METHODS: New adult patients (N = 509) were randomly assigned to primary care physicians at a university medical center. Their use of health care services and associated charges were monitored for 1 year of care. Self-reported health status was measured using the Medical Outcomes Study Short Form-36 (SF-36). We controlled for health status, sociodemographic information, and primary care physician specialty in the statistical analyses.
RESULTS: Women had significantly lower self-reported health status and lower mean education and income than men. Women had a significantly higher mean number of visits to their primary care clinic and diagnostic services than men. Mean charges for primary care, specialty care, emergency treatment, diagnostic services, and annual total charges were all significantly higher for women than men; however, there were no differences for mean hospitalizations or hospital charges. After controlling for health status, sociodemographics, and clinic assignment, women still had higher medical charges for all categories of charges except hospitalizations.
CONCLUSIONS: Women have higher medical care service utilization and higher associated charges than men. Although the appropriateness of these differences was not determined, these findings have implications for health care.
Studies have consistently shown that women use more health care services than men.1-4 Several explanations have been offered. These differences may be associated with reproductive biology and conditions specific to gender,3,5-6 higher rates of morbidity in women than in men,1-4 differences in health perceptions and the reporting of symptoms and illnesses,1-4 or a greater likelihood that women seek help for prevention and illness.1,2,4 Physician referral practice patterns may also partially explain the rates of specialty care and diagnostic testing. Men are referred to specialty care more often than women,7 and hospitalized men are more likely to be referred for invasive cardiac procedures than women.8-9
The authors of some previous studies describing gender differences in the use of health care services have examined large secondary data sets without incorporating important independent variables, such as sociodemographic information or patient health status.3-5 Other researchers have attempted to control for health status by including in the study population only those individuals rating their health as good or excellent.2 Still others have used limited health status measures that have not been tested for reliability and validity.1
Although there have been a number of studies demonstrating distinctive patterns in the use of health care by women, few have reported associated health care expenditure differences. A recent study from Canada (a country with a system of universal health insurance) presented data on the crude annual per capita use of health care resources for men and women in the province of Manitoba.5 Using administrative data from electronic records, the investigators concluded that expenditures for health care were similar for men and women. Unfortunately, data regarding individual health status, sociodemographics, or other possible confounders were unavailable.
The purpose of our study was to examine gender differences in the use of health care services and in the associated charges for 1 year of care. Since any cogent discussion of differential medical visit frequencies and charges requires controlling for sociodemographic and health status patient variables, these factors were incorporated. We chose an instrument widely used in health services research—the Medical Outcomes Study Short Form-36 (SF-36)—to measure self-reported health status. Also, because it has been demonstrated that medical specialty is associated with variations in resource utilization10 and that practice style differences between family physicians and general internists are associated with differential medical charges,11 our analyses also controlled for primary care physician specialty. We hypothesized that even after controlling for these factors women would have more medical care services use and higher charges than men.
Methods
Subjects
Our study population consisted of new patients requesting outpatient appointments at a university medical center. Of the first 956 nonpregnant adults having no preference for a specific physician or specialty, 821 (85%) agreed to participate. These patients were randomly assigned for primary care to either the family practice clinic or the general medicine clinic. Three hundred twelve (38%) of these patients were excluded from the study because they did not keep their appointment or could not be included for scheduling reasons. A total of 509 patients participated in the study, with no differential external health care utilization expected.
Procedures and Measures
We interviewed study participants before the initial visit with their primary care provider to collect sociodemographic data, and we used the SF-36 to determine self-reported health status. The SF-36 contains 8 scales: general health, physical function, physical role, mental role, social function, pain, energy, and mental health. Reliability and validity have been demonstrated for this questionnaire.12,13 Summary measures can be constructed for both physical and mental health status components.14
After a study period of 1 year, we contacted patients and asked them to complete exit interviews. A total of 417 (82%) returned follow-up questionnaires. Self-reported health status measures provided patient outcome data on changes in health status during the study period.
Medical care was provided by 26 family practice and 79 general internal medicine second- and third-year residents. Those 105 primary care physicians each saw an average of 4.8 patients (standard deviation = 4.6 patients).
Resource Use and Medical Charges
Medical center resource use for the 1 year of care was determined by review of the comprehensive unified medical record. Physician reviewers noted the number of primary care visits, specialty clinic visits, emergency department visits, hospitalizations, and laboratory, diagnostic, and radiological tests (diagnostic services). Medical charges for all these services were obtained from the institutional central billing unit used by both clinics. Charges, used as a proxy for medical costs, were assigned to 1 of 5 categories: primary care clinics, specialty care clinics, emergency departments, hospitals (including outpatient surgical), and diagnostic services. In addition, yearlong totals for the 5 types of charges were calculated for each patient.
Results
As shown in Table 1, the 509 study patients included 315 women (62%) and 194 men (38%). Mean age and ethnicity were not significantly different for the 2 genders. Women, however, had significantly lower mean education, income, and self-reported physical and mental health status as measured by the respective SF-36 components.
The use of health care services by men and women was compared with 2-tailed Student t tests Table 2. Women had a significantly higher mean number of visits to their primary care clinic (P = .0004) and a significantly higher mean number of diagnostic services ordered (P = .0005). There were no statistically significant gender differences in the mean number of specialty clinic visits, emergency department visits, or hospitalizations.
The mean and median annual per capita expenditures for the 5 categories of medical charges (and total charges) for women and men are displayed in Table 3. To reduce the influence of outliers, the natural logarithm of these charges (plus $10) was used to examine gender differences in medical care charges using 2-tailed Student t tests to compare the 5 categories of medical charges Table 4. Women had significantly higher primary care (P = .0010), specialty clinic (P = .0487), emergency department (P = .0065), diagnostic services (P = .0016), and total charges (P = .0037) than men. There was no significant difference in hospital charges.
Regression equations were then estimated to relate the logarithm of medical charges of all categories to gender, controlling for clinic assignment, self-reported physical and mental patient health status, age, education, and income Table 5. Clinic assignment was significantly related to primary care and emergency department charges. Approximately 17% of the variation in log-transformed total charges was explained by clinic assignment, physical and mental health status, age, education, income, and patient gender. Because the dependent variable is expressed in logs, exponentiation of the estimated coefficients for any of the indicator variables (for example, the coefficient 0.1468 for the variable “female” in the primary care equation) provides the percentage by which average charges for those patients having that characteristic exceed average charges for those who do not. Thus, women had 15.8% higher charges for primary care clinic visits than men. They also had 9.4% greater charges in specialty clinics, 9.6% higher charges for emergency department care, and 10.4% greater charges for diagnostic services. Overall, their charges exceeded those of men by a statistically and clinically significant 9.9%. Predictably, physical health status and age were significantly related to medical charges.
Following a year of care, we calculated change in self-reported health status (exit health status minus entry health status). There were no significant differences in change of physical or mental health status (P = .0651 and .3691, respectively) for women compared with men. The trend for women to report their physical health status as improved to a greater extent than men should be noted.
Discussion
Previous studies reporting that women use more medical services than men have suggested that this is due to gender differences in morbidity and self-reported health status.1-4,6 Indeed, women in our study reported both baseline physical and mental health status significantly lower than the men. We found the subsequent mean numbers of primary care visits and diagnostic services were significantly higher for women than for men. Primary care physicians may be more likely to order laboratory, radiologic, and other diagnostic tests for women who make more frequent visits and have continuing medical complaints. We did not, however, observe the higher referral rates to specialty care for men that others have found.7
Charges for primary care, specialty care, emergency treatment, diagnostic services, and yearlong total charges were all significantly higher for women. Although it is logical that the higher mean numbers of primary care visits and diagnostic tests for women would be associated with higher charges for these services, it was also observed that specialty care and emergency treatment charges were higher for women despite visit rates similar to those of men. The poorer health status of women may have led to more complicated and costlier care when they were seen in the specialty clinics or emergency department compared with men who had better baseline health. Both the mean number of hospitalizations and related hospital charges, however, were not different for men and women. This confirms the work of Verbrugge and Wingard,4 who also observed that although women use more outpatient services, they have similar or lower rates of hospitalization than men.
Regression equation analysis highlighted the importance of physical health status, age, and clinic assignment in the prediction of medical charges. Lower physical health status and advancing age both predicted higher medical charges. Clinic assignment was also found to be related to medical charges. As seen in our previous study,11 patients’ assignment to care by internists versus family physicians was associated with higher charges for primary care and emergency department care. Even after controlling for clinic assignment, health status, age, and other sociodemographic variables, women continued to be associated with higher medical charges for all categories of charges except hospitalizations. Higher health care utilization and associated charges did not lead to significantly better health outcomes for women.
The differences we found may result from patients’ health beliefs and help-seeking behavior. Women have been found to be more predisposed to report their health as poor.3 They also have a greater willingness and ability to take care of themselves when they are sick and to seek preventive care.4 Physicians, in turn, may respond to these attitudinal and behavioral characteristics in women by providing them with differential diagnosis and treatment.
The strengths of our study include the fact that we measured health status with a widely used instrument that allowed us to control for this important variable. We also controlled for sociodemographic variables and physician specialty to more accurately assess the influence of patient gender on health service utilization. In addition to information about utilization patterns, medical charge data were available to compare costs of care for men and women.
Limitations
There were a number of limitations which should also be noted. Our study was conducted at a university medical center with primary care resident physicians. These physicians-in-training may be more likely to differentially care for patients on the basis of patient gender. In addition, patients participating in the study had no preference for a specific physician or specialty. It may also be true that the study patients represent a different population than those cared for in the community. It was found, for example, that both the self-reported physical and mental health status scores for these study patients were lower than national means. Although we included only nonpregnant adults (not requiring obstetrical care) and controlled for health status, we did not attempt to control for differences in health care utilization associated with gender-specific problems. Also, we did not measure patient health attitudes, which may be an important factor in seeking and using health services.
Conclusions
Our hypothesis was confirmed: Women used more medical services and have higher outpatient expenditures than men, even when controlling for health status and other variables. We cannot judge the appropriateness of these gender differences in resource utilization. There was a trend, though not significant, for women to report a greater improvement in their physical health status than men. It is possible that these men underused health care resources and had unmet medical needs. Future studies examining differential health care utilization need to incorporate appropriate patient health outcome measures. This research has implications for health care organizations that seek to provide quality comprehensive care that is cost efficient for both men and women.
Acknowledgments
Our research was supported by the Agency for Health Care Policy and Research Grant R18 HS06167.
METHODS: New adult patients (N = 509) were randomly assigned to primary care physicians at a university medical center. Their use of health care services and associated charges were monitored for 1 year of care. Self-reported health status was measured using the Medical Outcomes Study Short Form-36 (SF-36). We controlled for health status, sociodemographic information, and primary care physician specialty in the statistical analyses.
RESULTS: Women had significantly lower self-reported health status and lower mean education and income than men. Women had a significantly higher mean number of visits to their primary care clinic and diagnostic services than men. Mean charges for primary care, specialty care, emergency treatment, diagnostic services, and annual total charges were all significantly higher for women than men; however, there were no differences for mean hospitalizations or hospital charges. After controlling for health status, sociodemographics, and clinic assignment, women still had higher medical charges for all categories of charges except hospitalizations.
CONCLUSIONS: Women have higher medical care service utilization and higher associated charges than men. Although the appropriateness of these differences was not determined, these findings have implications for health care.
Studies have consistently shown that women use more health care services than men.1-4 Several explanations have been offered. These differences may be associated with reproductive biology and conditions specific to gender,3,5-6 higher rates of morbidity in women than in men,1-4 differences in health perceptions and the reporting of symptoms and illnesses,1-4 or a greater likelihood that women seek help for prevention and illness.1,2,4 Physician referral practice patterns may also partially explain the rates of specialty care and diagnostic testing. Men are referred to specialty care more often than women,7 and hospitalized men are more likely to be referred for invasive cardiac procedures than women.8-9
The authors of some previous studies describing gender differences in the use of health care services have examined large secondary data sets without incorporating important independent variables, such as sociodemographic information or patient health status.3-5 Other researchers have attempted to control for health status by including in the study population only those individuals rating their health as good or excellent.2 Still others have used limited health status measures that have not been tested for reliability and validity.1
Although there have been a number of studies demonstrating distinctive patterns in the use of health care by women, few have reported associated health care expenditure differences. A recent study from Canada (a country with a system of universal health insurance) presented data on the crude annual per capita use of health care resources for men and women in the province of Manitoba.5 Using administrative data from electronic records, the investigators concluded that expenditures for health care were similar for men and women. Unfortunately, data regarding individual health status, sociodemographics, or other possible confounders were unavailable.
The purpose of our study was to examine gender differences in the use of health care services and in the associated charges for 1 year of care. Since any cogent discussion of differential medical visit frequencies and charges requires controlling for sociodemographic and health status patient variables, these factors were incorporated. We chose an instrument widely used in health services research—the Medical Outcomes Study Short Form-36 (SF-36)—to measure self-reported health status. Also, because it has been demonstrated that medical specialty is associated with variations in resource utilization10 and that practice style differences between family physicians and general internists are associated with differential medical charges,11 our analyses also controlled for primary care physician specialty. We hypothesized that even after controlling for these factors women would have more medical care services use and higher charges than men.
Methods
Subjects
Our study population consisted of new patients requesting outpatient appointments at a university medical center. Of the first 956 nonpregnant adults having no preference for a specific physician or specialty, 821 (85%) agreed to participate. These patients were randomly assigned for primary care to either the family practice clinic or the general medicine clinic. Three hundred twelve (38%) of these patients were excluded from the study because they did not keep their appointment or could not be included for scheduling reasons. A total of 509 patients participated in the study, with no differential external health care utilization expected.
Procedures and Measures
We interviewed study participants before the initial visit with their primary care provider to collect sociodemographic data, and we used the SF-36 to determine self-reported health status. The SF-36 contains 8 scales: general health, physical function, physical role, mental role, social function, pain, energy, and mental health. Reliability and validity have been demonstrated for this questionnaire.12,13 Summary measures can be constructed for both physical and mental health status components.14
After a study period of 1 year, we contacted patients and asked them to complete exit interviews. A total of 417 (82%) returned follow-up questionnaires. Self-reported health status measures provided patient outcome data on changes in health status during the study period.
Medical care was provided by 26 family practice and 79 general internal medicine second- and third-year residents. Those 105 primary care physicians each saw an average of 4.8 patients (standard deviation = 4.6 patients).
Resource Use and Medical Charges
Medical center resource use for the 1 year of care was determined by review of the comprehensive unified medical record. Physician reviewers noted the number of primary care visits, specialty clinic visits, emergency department visits, hospitalizations, and laboratory, diagnostic, and radiological tests (diagnostic services). Medical charges for all these services were obtained from the institutional central billing unit used by both clinics. Charges, used as a proxy for medical costs, were assigned to 1 of 5 categories: primary care clinics, specialty care clinics, emergency departments, hospitals (including outpatient surgical), and diagnostic services. In addition, yearlong totals for the 5 types of charges were calculated for each patient.
Results
As shown in Table 1, the 509 study patients included 315 women (62%) and 194 men (38%). Mean age and ethnicity were not significantly different for the 2 genders. Women, however, had significantly lower mean education, income, and self-reported physical and mental health status as measured by the respective SF-36 components.
The use of health care services by men and women was compared with 2-tailed Student t tests Table 2. Women had a significantly higher mean number of visits to their primary care clinic (P = .0004) and a significantly higher mean number of diagnostic services ordered (P = .0005). There were no statistically significant gender differences in the mean number of specialty clinic visits, emergency department visits, or hospitalizations.
The mean and median annual per capita expenditures for the 5 categories of medical charges (and total charges) for women and men are displayed in Table 3. To reduce the influence of outliers, the natural logarithm of these charges (plus $10) was used to examine gender differences in medical care charges using 2-tailed Student t tests to compare the 5 categories of medical charges Table 4. Women had significantly higher primary care (P = .0010), specialty clinic (P = .0487), emergency department (P = .0065), diagnostic services (P = .0016), and total charges (P = .0037) than men. There was no significant difference in hospital charges.
Regression equations were then estimated to relate the logarithm of medical charges of all categories to gender, controlling for clinic assignment, self-reported physical and mental patient health status, age, education, and income Table 5. Clinic assignment was significantly related to primary care and emergency department charges. Approximately 17% of the variation in log-transformed total charges was explained by clinic assignment, physical and mental health status, age, education, income, and patient gender. Because the dependent variable is expressed in logs, exponentiation of the estimated coefficients for any of the indicator variables (for example, the coefficient 0.1468 for the variable “female” in the primary care equation) provides the percentage by which average charges for those patients having that characteristic exceed average charges for those who do not. Thus, women had 15.8% higher charges for primary care clinic visits than men. They also had 9.4% greater charges in specialty clinics, 9.6% higher charges for emergency department care, and 10.4% greater charges for diagnostic services. Overall, their charges exceeded those of men by a statistically and clinically significant 9.9%. Predictably, physical health status and age were significantly related to medical charges.
Following a year of care, we calculated change in self-reported health status (exit health status minus entry health status). There were no significant differences in change of physical or mental health status (P = .0651 and .3691, respectively) for women compared with men. The trend for women to report their physical health status as improved to a greater extent than men should be noted.
Discussion
Previous studies reporting that women use more medical services than men have suggested that this is due to gender differences in morbidity and self-reported health status.1-4,6 Indeed, women in our study reported both baseline physical and mental health status significantly lower than the men. We found the subsequent mean numbers of primary care visits and diagnostic services were significantly higher for women than for men. Primary care physicians may be more likely to order laboratory, radiologic, and other diagnostic tests for women who make more frequent visits and have continuing medical complaints. We did not, however, observe the higher referral rates to specialty care for men that others have found.7
Charges for primary care, specialty care, emergency treatment, diagnostic services, and yearlong total charges were all significantly higher for women. Although it is logical that the higher mean numbers of primary care visits and diagnostic tests for women would be associated with higher charges for these services, it was also observed that specialty care and emergency treatment charges were higher for women despite visit rates similar to those of men. The poorer health status of women may have led to more complicated and costlier care when they were seen in the specialty clinics or emergency department compared with men who had better baseline health. Both the mean number of hospitalizations and related hospital charges, however, were not different for men and women. This confirms the work of Verbrugge and Wingard,4 who also observed that although women use more outpatient services, they have similar or lower rates of hospitalization than men.
Regression equation analysis highlighted the importance of physical health status, age, and clinic assignment in the prediction of medical charges. Lower physical health status and advancing age both predicted higher medical charges. Clinic assignment was also found to be related to medical charges. As seen in our previous study,11 patients’ assignment to care by internists versus family physicians was associated with higher charges for primary care and emergency department care. Even after controlling for clinic assignment, health status, age, and other sociodemographic variables, women continued to be associated with higher medical charges for all categories of charges except hospitalizations. Higher health care utilization and associated charges did not lead to significantly better health outcomes for women.
The differences we found may result from patients’ health beliefs and help-seeking behavior. Women have been found to be more predisposed to report their health as poor.3 They also have a greater willingness and ability to take care of themselves when they are sick and to seek preventive care.4 Physicians, in turn, may respond to these attitudinal and behavioral characteristics in women by providing them with differential diagnosis and treatment.
The strengths of our study include the fact that we measured health status with a widely used instrument that allowed us to control for this important variable. We also controlled for sociodemographic variables and physician specialty to more accurately assess the influence of patient gender on health service utilization. In addition to information about utilization patterns, medical charge data were available to compare costs of care for men and women.
Limitations
There were a number of limitations which should also be noted. Our study was conducted at a university medical center with primary care resident physicians. These physicians-in-training may be more likely to differentially care for patients on the basis of patient gender. In addition, patients participating in the study had no preference for a specific physician or specialty. It may also be true that the study patients represent a different population than those cared for in the community. It was found, for example, that both the self-reported physical and mental health status scores for these study patients were lower than national means. Although we included only nonpregnant adults (not requiring obstetrical care) and controlled for health status, we did not attempt to control for differences in health care utilization associated with gender-specific problems. Also, we did not measure patient health attitudes, which may be an important factor in seeking and using health services.
Conclusions
Our hypothesis was confirmed: Women used more medical services and have higher outpatient expenditures than men, even when controlling for health status and other variables. We cannot judge the appropriateness of these gender differences in resource utilization. There was a trend, though not significant, for women to report a greater improvement in their physical health status than men. It is possible that these men underused health care resources and had unmet medical needs. Future studies examining differential health care utilization need to incorporate appropriate patient health outcome measures. This research has implications for health care organizations that seek to provide quality comprehensive care that is cost efficient for both men and women.
Acknowledgments
Our research was supported by the Agency for Health Care Policy and Research Grant R18 HS06167.
1. PD, Mechanic D, Greenley JR. Sex differences in medical care utilization: an empirical investigation. J Health Soc Behav 1982;23:106-19.
2. Hibbard JH, Pope CR. Gender roles, illness orientation and use of medical services. Soc Sci Med 1983;17:129-37.
3. Waldron I. Sex differences in illness incidence, prognosis and mortality: issues and evidence. Soc Sci Med 1983;17:1107-23.
4. Verbrugge LM, Wingard DL. Sex differentials in health and mortality. Women Health 1987;12:103-45.
5. Mustard CA, Kaufert P, Kozyrsky A, Mayer T. Sex differences in the use of health care services. N Engl J Med 1998;338:1678-83.
6. Gijsbers van Wijk CMT, Kolk AM, van den Bosch WJHM, van den Hoogen HJM. Male and female morbidity in general practice: the nature of sex differences. Soc Sci Med 1992;35:665-78.
7. Franks P, Clancy CM. Referrals of adult patients from primary care: demographic disparities and their relationship to HMO insurance. J Fam Pract 1997;45:47-53.
8. Ayanian JZ, Epstein AM. Differences in the use of procedures between women and men hospitalized for coronary heart disease. N Engl J Med 1991;325:221-5.
9. Giles WH, Anda RF, Casper ML, Escobedo LG, Taylor HA. Race and sex differences in rates of invasive cardiac procedures in U.S. hospitals: data from the national hospital discharge survey. Arch Intern Med 1995;155:318-24.
10. S, Nelson EC, Zubkoff M, et al. Variations in resource utilization among medical specialties and systems of care. JAMA 1992;267:1624-30.
11. KD, Helms LJ, Azari R, Callahan EJ, Robbins JA, Miller J. Differences between family physicians’ and general internists’ medical charges. Med Care 1999;37:78-82.
12. CA, Ware JE, Lu JFR, Sherbourne CD. The MOS 36-item short-form health survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care 1994;32:40-66.
13. CA, Ware JE, Raczek AE. The MOS 36-item short-form health survey (SF-36): II. Psychometric and clinical tests of validity in measuring physical and mental health constructs. Med Care 1993;31:247-63.
14. JE, Kosinski M, Keller SD. SF-36 physical and mental health summary scales: a user’s manual. Boston, Mass: Nimrod Press, 1994.
1. PD, Mechanic D, Greenley JR. Sex differences in medical care utilization: an empirical investigation. J Health Soc Behav 1982;23:106-19.
2. Hibbard JH, Pope CR. Gender roles, illness orientation and use of medical services. Soc Sci Med 1983;17:129-37.
3. Waldron I. Sex differences in illness incidence, prognosis and mortality: issues and evidence. Soc Sci Med 1983;17:1107-23.
4. Verbrugge LM, Wingard DL. Sex differentials in health and mortality. Women Health 1987;12:103-45.
5. Mustard CA, Kaufert P, Kozyrsky A, Mayer T. Sex differences in the use of health care services. N Engl J Med 1998;338:1678-83.
6. Gijsbers van Wijk CMT, Kolk AM, van den Bosch WJHM, van den Hoogen HJM. Male and female morbidity in general practice: the nature of sex differences. Soc Sci Med 1992;35:665-78.
7. Franks P, Clancy CM. Referrals of adult patients from primary care: demographic disparities and their relationship to HMO insurance. J Fam Pract 1997;45:47-53.
8. Ayanian JZ, Epstein AM. Differences in the use of procedures between women and men hospitalized for coronary heart disease. N Engl J Med 1991;325:221-5.
9. Giles WH, Anda RF, Casper ML, Escobedo LG, Taylor HA. Race and sex differences in rates of invasive cardiac procedures in U.S. hospitals: data from the national hospital discharge survey. Arch Intern Med 1995;155:318-24.
10. S, Nelson EC, Zubkoff M, et al. Variations in resource utilization among medical specialties and systems of care. JAMA 1992;267:1624-30.
11. KD, Helms LJ, Azari R, Callahan EJ, Robbins JA, Miller J. Differences between family physicians’ and general internists’ medical charges. Med Care 1999;37:78-82.
12. CA, Ware JE, Lu JFR, Sherbourne CD. The MOS 36-item short-form health survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care 1994;32:40-66.
13. CA, Ware JE, Raczek AE. The MOS 36-item short-form health survey (SF-36): II. Psychometric and clinical tests of validity in measuring physical and mental health constructs. Med Care 1993;31:247-63.
14. JE, Kosinski M, Keller SD. SF-36 physical and mental health summary scales: a user’s manual. Boston, Mass: Nimrod Press, 1994.