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Estrogen replacement therapy among elderly women: results from the 1995 medicare current beneficiary survey
Article Estrogen Replacement Therapy Among Elderly Women: Results from the 1995 Medicare Current Beneficiary Survey Usha Sambamoorthi, PhD Stephen Crystal, PhD Rizie Kumar, MA Jeff Harman, PhD Institute for Health, Health Care Policy, and Aging Research Rutgers University New Brunswick, New Jersey
Research Objectives: To develop population-based estimates of estrogen replacement therapy use rates in 1995 among women over age 65 living in the community; to estimate the impact of socioeconomic and health characteristics on estrogen use. Method: Estimates are based on a large, nationally representative sample of Medicare beneficiaries; detailed self-report data were merged with Medicare claims. Results: Overall, 13.1% of women reported use of estrogen replacement therapy in 1995. Estrogen users were more likely to be white, age 65–74, with private insurance, high income, history of osteoporosis and heart problems, no history of breast cancer, and a patient of gynecologists. Conclusions: Estrogen use was substantially lower among the socioeconomically disadvantaged, controlling for medical history variables, suggesting considerable inequity in access to estrogen replacement therapy treatment.
E
strogen replacement therapy (ERT) has been a controversial preventive and therapeutic treatment, particularly for women over age 65. Beneficial effects, including prevention of osteoporotic fractures and lower risk of coronary artery disease, as well as negative effects including increased risk of breast cancer are documented in the literature.1 Because heart disease is by far the leading cause of death among older women, many medical experts believe that the overall effect of ERT for older women is decidedly beneficial.2 Guidelines from major medical organizations encourage offering of ERT to all postmenopausal women,3 and widely disseminated advice to consumers from sources such as the American Medical Association encourages its use.4 However, the decision to seek ERT is a complex one influenced by factors at the patient, provider, and care system levels. Patient factors include demographic characteristics, economic circumstances, health status, risk of breast and uterine cancer, and medical comorbidities. There has been considerable observational research on the influence of these patient level factors on use of ERT. However, there have still been only a handful of published papers specifically on ERT issues for older women. Nationally representative studies
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© 1999 by the Jacobs Institute of Women’s Health Published by Elsevier Science Inc. 1049-3867/99/$20.00 PII S1049-3867(99)00019-5
on ERT typically include both middle-aged and older women, and use age only as a covariate rather than providing analyses that are specific to the experience of the patients in the oldest age brackets.5–7 Studies that do focus on elderly women have typically included only subgroups of the population such as whites,8 residents of a particular geographic region,9 or health maintenance organization (HMO) participants,10 thus limiting the generalizability of ERT estimates from these studies. Some of these observational studies suggest the existence of substantial differences in use of ERT by race, education, income,5,6,8,9 and sector of care.7 Recent nationally representative estimates of ERT use have been based either on the National Ambulatory Medical Care Survey (NAMCS)5,7,11 or the First National Health and Nutrition Examination Survey (NHEFS).6 However, neither data set is an ideal source of information on ERT use. NAMCS is based on individuals seeking care in office settings and does not capture care received at hospital clinics, which are an important source of care for economically disadvantaged subgroups. Also, the sampling unit in the NAMCS data is the visit and not the individual. Because not all office visits to a patient receiving ERT generate a new or renewal prescription for ERT, and frequency of office visits (and hence, probability of selection) varies across individuals, estimates of use are likely to be biased. NHEFS, which asked only about “hormone pills for reasons related to menopause,” may miss estrogen use considered by respondents-to-be for purposes unrelated to menopause (such as prevention of osteoporosis). Furthermore, NHEFS-based estimates reflect ERT use only through 1992. In contrast, the present study used the 1995 Medicare Current Beneficiary Survey (MCBS), a nationally representative survey of Medicare beneficiaries, to explore use of estrogens and assess the impact of patient characteristics on ERT among elderly women living in the community. Because nearly all U.S. elderly receive Medicare, MCBS respondents over age 65 (with appropriate weights) essentially represent the U.S. elderly population. Strengths of our study include the availability of patient level data, nationally representative study design, presence of detailed pharmacy information, and availability of claims information on use of physician services.
METHODS Study Population We used data from the 1995 MCBS’s Cost and Use files, including information on medical history, health services use including pharmaceuticals, insurance, and other characteristics, as well as Medicare claims. Estimates are based on women beneficiaries aged 65 or older enrolled in Medicare, not participating in managed care plans, and living in the community at each interview. The final sample size (unweighted) included 4,365 elderly women.
Variables Estrogen Use The dependent variable was whether the respondent used estrogen drugs in 1995. Estrogen use was assessed from the information on each filled prescription obtained by the MCBS in personal interviews conducted at 4-month intervals. To assist in accurate reporting of prescription medicines, MCBS respondents were asked to bring medication containers provided by the pharmacy to the interview. Estrogen drug names, both generic and brand name, were obtained from the 1997 Physicians’ desk reference and were identi-
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fied by drug names recorded in the pharmacy file of the MCBS. A complete list of estrogen drug names used in the study is available from the authors. Socioeconomic Variables and Care Sector Socioeconomic variables included age, race, education, marital status, income, type of insurance, and prescription coverage. Elderly patients may face financial barriers to treatment. Depending on a patient’s income and insurance coverage, cost barriers may be significant because Medicare does not cover prescription drug use. The income variable in the MCBS was measured for the respondent, or the respondent and spouse if married for the calendar year. We created a dummy variable for income representing respondents with income below 200% of the poverty line. Type of insurance was derived from survey responses on monthly insurance coverage additional to Medicare. Respondents were assigned to the following hierarchy: private/employment-sponsored coverage; self-purchased insurance but no employment-sponsored coverage; Medicaid; and Medicare only. For each policy, MCBS collected information on whether the policy covered prescription drugs, making it possible to investigate the relationship between prescription drug coverage and ERT use. Using this information, we constructed a binary variable representing prescription coverage during the year. To explore differences in treatment patterns associated with sector of care, we created a variable indicating whether a woman made at least one visit to a gynecologist, based on provider specialty codes recorded in paid claims. Because we believed that seeking treatment from a gynecologist would be an important predictor of ERT use and because women enrolled in managed care plans did not have claims histories, we excluded these women from the analysis. Health Status and Medical History Health perceptions were measured by a standard self-reported health item (excellent/very good, good, fair, or poor). Risk factors included a history of coronary heart disease, stroke, breast cancer, hip fracture, diabetes mellitus, hysterectomy, or osteoporosis. Other health variables included smoking (current smoker/nonsmoker) and body mass index (BMI) (of 30 or higher/BMI under 30).
Statistical Analysis We examined correlates of current estrogen use with both bivariate and multivariate statistical techniques. Bivariate differences were tested with chi-square tests. Logistic regression on estrogen use was employed to control for the independent variables simultaneously. MCBS uses a stratified, multistage, area probability sample of the Medicare population drawn from HCFA’s Medicare enrollment file, with oversampling of the oldest old. In the statistical analysis, all data were weighted to represent the national Medicare-enrolled population and adjust for oversampling. In both bivariate and multivariate analyses, we estimated standard errors using linearization methods that account for intracluster correlation in the multilevel sampling design used by MCBS, using the survey procedures of the STATA statistical software system.12
RESULTS Table 1 presents the weighted percentage with ERT use. Overall, 13.1% reported use of ERT in 1995. In bivariate analysis, estrogen use was significantly associated with most of the socioeconomic variables. The rate of ERT use was particularly low among blacks (4.4%) and among those with only 288
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Table 1. RATES OF ESTROGEN USE BY CHARACTERISTICS OF STUDY SAMPLE
Characteristic
All Race* White Black Age* 65–74 ⱖ75 Education* Did not complete high school High school graduate Some college/coll. graduate Marital status* Currently married Not married Insurance coverage* Employer-sponsored Self-purchased Medicaid Medicare only Income* Low income Other Prescription drug coverage Yes No Saw gynecologist* Yes No Self-reported health status Excellent/very good Good Fair Poor Body mass index* 30 ⱖ30 Current smoking* Yes No History of coronary heart disease* Yes No History of stroke* Yes No History of breast cancer* Yes No
Estrogen users
Percentage of sample
%
95% CI
100.0
13.1
11.7, 14.5
88.5 11.5
14.2 4.4
12.7, 15.8 2.4, 06.5
52.8 47.2
16.4 9.4
14.3, 18.6 8.2, 10.6
40.3 34.9 24.8
9.2 14.7 17.5
7.5, 10.8 12.4, 17.1 14.8, 20.1
40.0 59.9
17.2 10.4
15.0, 19.4 9.0, 11.7
38.0 40.4 12.8 8.8
16.6 13.9 5.9 4.9
14.4, 18.9 11.9, 15.9 3.7, 8.0 2.6, 7.2
58.6 41.4
9.4 18.4
8.0, 10.7 16.1, 20.8
54.8 45.2
13.9 12.1
12.1, 15.8 10.5, 13.8
10.6 89.4
33.3 10.7
28.1, 38.6 9.4, 12.1
45.7 29.4 17.5 7.4
14.2 12.9 11.6 11.3
12.4, 16.3 10.4, 15.3 9.1, 14.1 7.6, 15.1
81.3 18.7
13.9 10.1
12.3, 15.5 7.6, 12.7
10.7 89.3
8.7 13.6
5.5, 11.9 12.2, 15.1
14.7 85.3
15.9 12.6
13.1, 18.8 11.1, 14.1
10.6 89.6
9.8 13.5
6.2, 13.3 12.0, 15.0
7.5 92.5
5.3 13.7
2.9, 7.8 12.3, 15.2
Continued on next page
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Table 1 (Continued)
Characteristic
History of broken hip Yes No History of diabetes* Yes No Hysterectomy* Yes No Osteoporosis* Yes No Region* Northeast Midwest South West No. of observations
Percentage of sample
Estrogen users %
95% CI
5.4 94.6
11.9 13.2
8.2, 15.6 11.8, 14.6
16.6 83.4
8.3 14.1
5.8, 10.8 12.5, 15.6
27.3 72.7
17.0 11.7
14.6, 19.4 10.3, 13.1
17.3 82.7
20.0 11.7
16.5, 23.6 10.3, 13.0
22.7 25.1 39.6 12.6 4,365
5.7 12.6 15.5 20.2 517
3.7, 7.7 10.8, 14.4 12.9, 18.0 15.0, 25.4
The study sample was restricted to women age 65 years or older on Medicare, not participating in managed care plans, and living in the community during 1995. The tabulations are weighted to account for the design effects of the MCBS. Low income represents respondents with household income 200% of the poverty line. *Intergroup differences are statistically significant at P ⬍ .05. CI ⫽ confidence interval.
Medicare (4.9%). There was a dramatic difference in the rate of ERT between women who had at least one visit to a gynecologist and women who did not go to gynecologists (33.3% versus 10.7%). ERT use was higher among women with a history of osteoporosis (20.0%) or hysterectomy (17.0%), and lower among those with a history of breast cancer (5.3%). Odds ratios and 95% confidence intervals from the logistic regression on use of ERT are presented in Table 2. Most of the socioeconomic characteristics that were predictive in the bivariate analysis remained so, although education and marital status were no longer significant. Controlling for a range of physical health conditions, medical risk factors, and socioeconomic characteristics, blacks were less likely to report current use of ERT than whites. Reliance on Medicare alone was associated with a substantially lower ERT use rate. Very low rates of treatment were observed among women 75 years of age or older. As in bivariate analysis, history of osteoporosis, heart disease or hysterectomy was associated with higher odds of ERT use, whereas history of breast cancer was associated with decreased odds. Current smokers were less likely to use ERT. Controlling for other characteristics, use of the specialty sector was strongly associated with higher ERT use. Patients with at least one visit to a gynecologist were nearly five times as likely to report ERT use. Use varied substantially by region; it was highest in the west and lowest in the northeast. Prescription drug coverage, health status, obesity, history of diabetes, stroke, and hip fracture did not have a significant effect on ERT use.
DISCUSSION Using nationally representative data on Medicare beneficiaries, this study examined the prevalence and correlates of current ERT use. The rate reported 290
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Table 2. PREDICTORS OF ESTROGEN USE AMONG ELDERLY MEDICARE BENEFICIARIES
Characteristic
Race Reference: white Black Age Reference: 65–74 ⱖ75 Education Reference: did not complete high school High school graduate Some college/coll. graduate Marital status Currently married Reference: not married Insurance coverage Employer-sponsored Self-purchased Medicaid Reference: Medicare only Income Low income Reference: other Prescription drug coverage Yes Reference: no Saw gynecologist Yes Reference: no Self-reported health status Excellent/very good Good Fair Reference: poor Body mass index Reference: ⬍30 ⱖ30 Smoking Yes Reference: no History of coronary heart disease Yes Reference: no History of stroke Yes Reference: no History of breast cancer Yes Reference: no
Odds ratio
95% confidence interval
P value
0.46
0.27, 0.79
.005
0.54
0.42, 0.69
.000
1.16 1.21
0.87, 1.54 0.91, 1.61
.312 .198
1.13
0.89, 1.43
.320
2.75 2.70 1.66
1.45, 5.20 1.40, 5.21 0.80, 3.45
.002 .003 .174
0.66
0.51, 0.85
.001
1.00
0.77, 1.29
.984
4.79
3.50, 6.54
.000
0.84 0.89 0.86
0.49, 1.45 0.54, 1.45 0.48, 1.45
.542 .626 .623
0.76
0.57, 1.01
.06
0.60
0.37, 0.95
.031
1.49
1.11, 2.00
.008
0.87
0.54, 1.41
.580
0.24
0.13, 0.43
.000
Continued on next page
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Table 2 (Continued)
Characteristic
History of broken hip Yes Reference: no History of diabetes Yes Reference: no Hysterectomy Yes Reference: no Osteoporosis Yes Reference: no Region Reference: Northeast Midwest South West
Odds ratio
95% confidence interval
P value
0.96
0.63, 1.47
.864
0.70
0.47, 1.06
.090
2.11
1.70, 2.62
.000
1.72
1.32, 2.24
.000
2.65 3.93 5.30
1.72, 4.08 2.50, 6.18 3.14, 8.94
.000 .000 .000
The study sample was restricted to women age 65 years or older on Medicare, not participating in managed care plans, and living in the community during the calendar year. The tabulations are weighted to account for the design effects of the MCBS. Low income represents respondents with household income 200% of the poverty line.
in our study (13.1%) is substantially lower than the 19 – 46% for the comparable age group reported in the NHEFS study cohort.6 This difference in reported rates may be due to differences in the definition of ERT use; whereas our study reported use of estrogens during the current calendar year, the NHEFS study was based on cumulative incidence (“ever used”) of ERT. Because women tend to discontinue use of estrogens, our estimates will be lower than those obtained using measures of ever-used ERT.6,9,13 The findings of lower rates of ERT use among blacks are consistent with results from previous studies.5,6,9,14 The racial difference is often interpreted as reflecting biological differences, such as the lower incidence of osteoporosis among black women. However, in our study, even after controlling for history of osteoporosis, the racial differences persisted. The low proportion of ERT use among black women could reflect slower adoption of treatment technologies by disadvantaged subgroups.15 Results from recent studies on the declining impact of race on estrogen use seem to support this.11,16 A striking finding of our study was the differences in ERT treatment patterns between specialists and generalists, perhaps because specialists tend to be more knowledgeable than generalists with respect to efficacious therapies, including appropriate pharmacotherapy.7,17–19 For example, among surveyed physicians, gynecologists believed in preventive hormone replacement therapy more strongly than family physicians and general internists, and ranked it second of eight preventive therapies.20 The lower probability of estrogen use by women with a history of breast cancer and the higher likelihood of ERT use by women with osteoporosis and heart disease most likely reflect appropriate differences in patterns of care based on current knowledge of the risks and benefits associated with ERT. However, overall, the rate of ERT treatment is quite low among women over 65, especially among women who are black, of low income, and/or who lack health insurance supplemental to Medicare. The extent to which use is 292
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determined by socioeconomic rather than medical characteristics suggests considerable inequity in access to ERT treatment. Our results suggest that the key barriers to access to ERT may be related to differences in access to physician care. Women who lack insurance supplemental to Medicare face significant out-of-pocket expenses each time they see a physician. They may be less likely to seek such care for preventive purposes rather than for the treatment of acute illnesses. Interestingly, coverage specifically for pharmaceuticals was not related to ERT use; this may reflect the mediating role of physicians’ recommendations in women’s choices. In contrast, contact with a gynecologist was strongly associated with use of ERT, suggesting that specialty sector care is an important mediating factor in ERT use. However, black race remained associated with a much lower rate of ERT use, even controlling for other socioeconomic factors as well as sector of care and health factors, indicating that cultural factors may also play important independent roles in the choice to use ERT. Some limitations to this study should be noted. This study does not capture use in the managed care sector, which is becoming an important source of health care delivery for Americans.21 In addition, we did not have the ability to assess the timing of initiation or discontinuation of ERT use or to examine the correlates of ERT at the time of initiation. There is a need for representative, longitudinal studies that can distinguish between ERT use that is initiated in late life and ERT use that is initiated earlier— eg, in the perimenopausal period—and continued into late life. Despite these limitations, our study provides important recent nationally representative data on the prevalence of ERT use among elderly Medicare beneficiaries. The study also contributes unique information about the relationship between the sector of care and estrogen use at the patient level. Our results confirm the existence of substantial socioeconomic differences in the use of ERT, even after controlling for a range of medical risk factors and health status. Although there is some evidence that socioeconomic differences in ERT use may have narrowed in recent years,11 our results suggest that substantial differences remain in access to ERT therapy among elderly women.
ACKNOWLEDGMENTS This research was supported in part by grants from the Agency for Health Care Policy and Research and the National Institute on Aging. The findings and opinions reported here are those of the authors and do not necessarily represent the views of any other individuals or organizations.
REFERENCES 1. Jacobs S, Hillard TC. Hormone replacement therapy in the aged: a state of the art review. Drugs Aging 1996;8:193–213. 2. Gorsky RD, Koplan JP, Peterson HB, Thaker SB. Relative risks and benefits of long-term estrogen replacement therapy: a decision analysis. Obstet Gynecol 1994;83:161– 6. 3. Grady D, Cummings SR, Pettiti D, Rubin SM, Audet A. Guidelines for counseling postmenopausal women about preventive hormone therapy. Ann Intern Med 1992;117:1038 – 41. 4. American Medical Association. Essential guide to menopause. New York: Pocket Books, 1998. 5. Bartman B, Moy E. Racial differences in estrogen use among middle-aged and older women. Womens Health Issues 1998;8:32– 44. 6. Brett KM, Madans JH. Use of postmenopausal hormone replacement therapy:
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estimates from a nationally representative cohort study. Am J Epidemiol 1997;145: 536 – 45. Stafford RS, Saglam D, Causino N, Blumenthal D. Low rates of hormone replacement therapy in visits to United States primary care physicians. Am J Obstet Gynecol 1997;177:381–7. Cauley JA, Cummings SR, Black DM, Mascioli SR, Seeley DG. Prevalence and determinants of estrogen replacement therapy in elderly women. Am J Obstet Gynecol 1990;163:1438 – 44. Handa VL, Landerman R, Hanlon JT, Harris T, Cohen HJ. Do older women use estrogen replacement? Data from the Duke Established Populations for Epidemiologic Studies of the Elderly. J Am Geriatr Soc 1996;44:1– 6. Leveille SG, LaCroix AZ, Newton KM, Keenan NL. Older women and hormone replacement therapy: factors influencing late life initiation. J Am Geriatr Soc 1997;45:1496 –500. Stafford RS, Saglam D, Causino N, Blumenthal D. The declining impact of race and insurance on hormone replacement therapy. Menopause 1998;5:140 – 4. StataCorp. Stata Statistical Software: Release 5.0. College Station, TX: Stata Corporation, 1997. Groeneveld FP, Bareman FP, Barentsen R, Dokter HJ, Drogendijk AC, Hoes AW. Duration of hormonal replacement therapy in general practice: a follow-up study. Maturitas 1998;29:125–31. Langenberg P, Kjerulff KH, Stolley PD. Hormone replacement therapy and menopausal symptoms following hysterectomy. Am J Epidemiol 1996;146:870 – 80. Crystal S, Sambamoorthi U, Merzel C. The diffusion of innovation in AIDS treatment: Zidovudine use in two New Jersey cohorts. Health Services Res 1995;30:593– 614. Jahnie K, Fieback N. Postmenopausal estrogen use among African American and white patients at an urban clinic. J Womens Health 1997;6:93–101. Fendrick A, Hirth R, Chernew M. Differences between generalist and specialist physicians regarding helicobacter pylori and peptic ulcer disease. Am J Gastroenterol 1996;91:1544 – 8. Donohue M. Comparing generalist and specialty care: discrepancies, deficiencies, and excesses. Arch Intern Med 1998;158:1596 – 608. Markson LE, Cosler LE, Turner BJ. Implications of generalists’ slow adoption of Zidovudine in clinical practice. Arch Intern Med 1994;154:1497–504. Saver BG, Taylor TR, Woods NF, Stevens NG. Physician policies on the use of preventive hormone therapy. Am J Prevent Med 1997;13:358 – 65. Gabel J. Ten ways HMOs have changed during the 1990s. Health Affairs 1997;16: 134 – 45.
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Research Objectives: To develop population-based estimates of estrogen replacement therapy use rates in 1995 among women over age 65 living in the community; to estimate the impact of socioeconomic and health characteristics on estrogen use. Method: Estimates are based on a large, nationally representative sample of Medicare beneficiaries; detailed self-report data were merged with Medicare claims. Results: Overall, 13.1% of women reported use of estrogen replacement therapy in 1995. Estrogen users were more likely to be white, age 65–74, with private insurance, high income, history of osteoporosis and heart problems, no history of breast cancer, and a patient of gynecologists. Conclusions: Estrogen use was substantially lower among the socioeconomically disadvantaged, controlling for medical history variables, suggesting considerable inequity in access to estrogen replacement therapy treatment.
E
strogen replacement therapy (ERT) has been a controversial preventive and therapeutic treatment, particularly for women over age 65. Beneficial effects, including prevention of osteoporotic fractures and lower risk of coronary artery disease, as well as negative effects including increased risk of breast cancer are documented in the literature.1 Because heart disease is by far the leading cause of death among older women, many medical experts believe that the overall effect of ERT for older women is decidedly beneficial.2 Guidelines from major medical organizations encourage offering of ERT to all postmenopausal women,3 and widely disseminated advice to consumers from sources such as the American Medical Association encourages its use.4 However, the decision to seek ERT is a complex one influenced by factors at the patient, provider, and care system levels. Patient factors include demographic characteristics, economic circumstances, health status, risk of breast and uterine cancer, and medical comorbidities. There has been considerable observational research on the influence of these patient level factors on use of ERT. However, there have still been only a handful of published papers specifically on ERT issues for older women. Nationally representative studies
286
WOMEN’S HEALTH ISSUES VOL. 9, NO. 6 NOVEMBER/DECEMBER 1999
© 1999 by the Jacobs Institute of Women’s Health Published by Elsevier Science Inc. 1049-3867/99/$20.00 PII S1049-3867(99)00019-5
on ERT typically include both middle-aged and older women, and use age only as a covariate rather than providing analyses that are specific to the experience of the patients in the oldest age brackets.5–7 Studies that do focus on elderly women have typically included only subgroups of the population such as whites,8 residents of a particular geographic region,9 or health maintenance organization (HMO) participants,10 thus limiting the generalizability of ERT estimates from these studies. Some of these observational studies suggest the existence of substantial differences in use of ERT by race, education, income,5,6,8,9 and sector of care.7 Recent nationally representative estimates of ERT use have been based either on the National Ambulatory Medical Care Survey (NAMCS)5,7,11 or the First National Health and Nutrition Examination Survey (NHEFS).6 However, neither data set is an ideal source of information on ERT use. NAMCS is based on individuals seeking care in office settings and does not capture care received at hospital clinics, which are an important source of care for economically disadvantaged subgroups. Also, the sampling unit in the NAMCS data is the visit and not the individual. Because not all office visits to a patient receiving ERT generate a new or renewal prescription for ERT, and frequency of office visits (and hence, probability of selection) varies across individuals, estimates of use are likely to be biased. NHEFS, which asked only about “hormone pills for reasons related to menopause,” may miss estrogen use considered by respondents-to-be for purposes unrelated to menopause (such as prevention of osteoporosis). Furthermore, NHEFS-based estimates reflect ERT use only through 1992. In contrast, the present study used the 1995 Medicare Current Beneficiary Survey (MCBS), a nationally representative survey of Medicare beneficiaries, to explore use of estrogens and assess the impact of patient characteristics on ERT among elderly women living in the community. Because nearly all U.S. elderly receive Medicare, MCBS respondents over age 65 (with appropriate weights) essentially represent the U.S. elderly population. Strengths of our study include the availability of patient level data, nationally representative study design, presence of detailed pharmacy information, and availability of claims information on use of physician services.
METHODS Study Population We used data from the 1995 MCBS’s Cost and Use files, including information on medical history, health services use including pharmaceuticals, insurance, and other characteristics, as well as Medicare claims. Estimates are based on women beneficiaries aged 65 or older enrolled in Medicare, not participating in managed care plans, and living in the community at each interview. The final sample size (unweighted) included 4,365 elderly women.
Variables Estrogen Use The dependent variable was whether the respondent used estrogen drugs in 1995. Estrogen use was assessed from the information on each filled prescription obtained by the MCBS in personal interviews conducted at 4-month intervals. To assist in accurate reporting of prescription medicines, MCBS respondents were asked to bring medication containers provided by the pharmacy to the interview. Estrogen drug names, both generic and brand name, were obtained from the 1997 Physicians’ desk reference and were identi-
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fied by drug names recorded in the pharmacy file of the MCBS. A complete list of estrogen drug names used in the study is available from the authors. Socioeconomic Variables and Care Sector Socioeconomic variables included age, race, education, marital status, income, type of insurance, and prescription coverage. Elderly patients may face financial barriers to treatment. Depending on a patient’s income and insurance coverage, cost barriers may be significant because Medicare does not cover prescription drug use. The income variable in the MCBS was measured for the respondent, or the respondent and spouse if married for the calendar year. We created a dummy variable for income representing respondents with income below 200% of the poverty line. Type of insurance was derived from survey responses on monthly insurance coverage additional to Medicare. Respondents were assigned to the following hierarchy: private/employment-sponsored coverage; self-purchased insurance but no employment-sponsored coverage; Medicaid; and Medicare only. For each policy, MCBS collected information on whether the policy covered prescription drugs, making it possible to investigate the relationship between prescription drug coverage and ERT use. Using this information, we constructed a binary variable representing prescription coverage during the year. To explore differences in treatment patterns associated with sector of care, we created a variable indicating whether a woman made at least one visit to a gynecologist, based on provider specialty codes recorded in paid claims. Because we believed that seeking treatment from a gynecologist would be an important predictor of ERT use and because women enrolled in managed care plans did not have claims histories, we excluded these women from the analysis. Health Status and Medical History Health perceptions were measured by a standard self-reported health item (excellent/very good, good, fair, or poor). Risk factors included a history of coronary heart disease, stroke, breast cancer, hip fracture, diabetes mellitus, hysterectomy, or osteoporosis. Other health variables included smoking (current smoker/nonsmoker) and body mass index (BMI) (of 30 or higher/BMI under 30).
Statistical Analysis We examined correlates of current estrogen use with both bivariate and multivariate statistical techniques. Bivariate differences were tested with chi-square tests. Logistic regression on estrogen use was employed to control for the independent variables simultaneously. MCBS uses a stratified, multistage, area probability sample of the Medicare population drawn from HCFA’s Medicare enrollment file, with oversampling of the oldest old. In the statistical analysis, all data were weighted to represent the national Medicare-enrolled population and adjust for oversampling. In both bivariate and multivariate analyses, we estimated standard errors using linearization methods that account for intracluster correlation in the multilevel sampling design used by MCBS, using the survey procedures of the STATA statistical software system.12
RESULTS Table 1 presents the weighted percentage with ERT use. Overall, 13.1% reported use of ERT in 1995. In bivariate analysis, estrogen use was significantly associated with most of the socioeconomic variables. The rate of ERT use was particularly low among blacks (4.4%) and among those with only 288
WOMEN’S HEALTH ISSUES VOL. 9, NO. 6 NOVEMBER/DECEMBER 1999
Table 1. RATES OF ESTROGEN USE BY CHARACTERISTICS OF STUDY SAMPLE
Characteristic
All Race* White Black Age* 65–74 ⱖ75 Education* Did not complete high school High school graduate Some college/coll. graduate Marital status* Currently married Not married Insurance coverage* Employer-sponsored Self-purchased Medicaid Medicare only Income* Low income Other Prescription drug coverage Yes No Saw gynecologist* Yes No Self-reported health status Excellent/very good Good Fair Poor Body mass index* 30 ⱖ30 Current smoking* Yes No History of coronary heart disease* Yes No History of stroke* Yes No History of breast cancer* Yes No
Estrogen users
Percentage of sample
%
95% CI
100.0
13.1
11.7, 14.5
88.5 11.5
14.2 4.4
12.7, 15.8 2.4, 06.5
52.8 47.2
16.4 9.4
14.3, 18.6 8.2, 10.6
40.3 34.9 24.8
9.2 14.7 17.5
7.5, 10.8 12.4, 17.1 14.8, 20.1
40.0 59.9
17.2 10.4
15.0, 19.4 9.0, 11.7
38.0 40.4 12.8 8.8
16.6 13.9 5.9 4.9
14.4, 18.9 11.9, 15.9 3.7, 8.0 2.6, 7.2
58.6 41.4
9.4 18.4
8.0, 10.7 16.1, 20.8
54.8 45.2
13.9 12.1
12.1, 15.8 10.5, 13.8
10.6 89.4
33.3 10.7
28.1, 38.6 9.4, 12.1
45.7 29.4 17.5 7.4
14.2 12.9 11.6 11.3
12.4, 16.3 10.4, 15.3 9.1, 14.1 7.6, 15.1
81.3 18.7
13.9 10.1
12.3, 15.5 7.6, 12.7
10.7 89.3
8.7 13.6
5.5, 11.9 12.2, 15.1
14.7 85.3
15.9 12.6
13.1, 18.8 11.1, 14.1
10.6 89.6
9.8 13.5
6.2, 13.3 12.0, 15.0
7.5 92.5
5.3 13.7
2.9, 7.8 12.3, 15.2
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Table 1 (Continued)
Characteristic
History of broken hip Yes No History of diabetes* Yes No Hysterectomy* Yes No Osteoporosis* Yes No Region* Northeast Midwest South West No. of observations
Percentage of sample
Estrogen users %
95% CI
5.4 94.6
11.9 13.2
8.2, 15.6 11.8, 14.6
16.6 83.4
8.3 14.1
5.8, 10.8 12.5, 15.6
27.3 72.7
17.0 11.7
14.6, 19.4 10.3, 13.1
17.3 82.7
20.0 11.7
16.5, 23.6 10.3, 13.0
22.7 25.1 39.6 12.6 4,365
5.7 12.6 15.5 20.2 517
3.7, 7.7 10.8, 14.4 12.9, 18.0 15.0, 25.4
The study sample was restricted to women age 65 years or older on Medicare, not participating in managed care plans, and living in the community during 1995. The tabulations are weighted to account for the design effects of the MCBS. Low income represents respondents with household income 200% of the poverty line. *Intergroup differences are statistically significant at P ⬍ .05. CI ⫽ confidence interval.
Medicare (4.9%). There was a dramatic difference in the rate of ERT between women who had at least one visit to a gynecologist and women who did not go to gynecologists (33.3% versus 10.7%). ERT use was higher among women with a history of osteoporosis (20.0%) or hysterectomy (17.0%), and lower among those with a history of breast cancer (5.3%). Odds ratios and 95% confidence intervals from the logistic regression on use of ERT are presented in Table 2. Most of the socioeconomic characteristics that were predictive in the bivariate analysis remained so, although education and marital status were no longer significant. Controlling for a range of physical health conditions, medical risk factors, and socioeconomic characteristics, blacks were less likely to report current use of ERT than whites. Reliance on Medicare alone was associated with a substantially lower ERT use rate. Very low rates of treatment were observed among women 75 years of age or older. As in bivariate analysis, history of osteoporosis, heart disease or hysterectomy was associated with higher odds of ERT use, whereas history of breast cancer was associated with decreased odds. Current smokers were less likely to use ERT. Controlling for other characteristics, use of the specialty sector was strongly associated with higher ERT use. Patients with at least one visit to a gynecologist were nearly five times as likely to report ERT use. Use varied substantially by region; it was highest in the west and lowest in the northeast. Prescription drug coverage, health status, obesity, history of diabetes, stroke, and hip fracture did not have a significant effect on ERT use.
DISCUSSION Using nationally representative data on Medicare beneficiaries, this study examined the prevalence and correlates of current ERT use. The rate reported 290
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Table 2. PREDICTORS OF ESTROGEN USE AMONG ELDERLY MEDICARE BENEFICIARIES
Characteristic
Race Reference: white Black Age Reference: 65–74 ⱖ75 Education Reference: did not complete high school High school graduate Some college/coll. graduate Marital status Currently married Reference: not married Insurance coverage Employer-sponsored Self-purchased Medicaid Reference: Medicare only Income Low income Reference: other Prescription drug coverage Yes Reference: no Saw gynecologist Yes Reference: no Self-reported health status Excellent/very good Good Fair Reference: poor Body mass index Reference: ⬍30 ⱖ30 Smoking Yes Reference: no History of coronary heart disease Yes Reference: no History of stroke Yes Reference: no History of breast cancer Yes Reference: no
Odds ratio
95% confidence interval
P value
0.46
0.27, 0.79
.005
0.54
0.42, 0.69
.000
1.16 1.21
0.87, 1.54 0.91, 1.61
.312 .198
1.13
0.89, 1.43
.320
2.75 2.70 1.66
1.45, 5.20 1.40, 5.21 0.80, 3.45
.002 .003 .174
0.66
0.51, 0.85
.001
1.00
0.77, 1.29
.984
4.79
3.50, 6.54
.000
0.84 0.89 0.86
0.49, 1.45 0.54, 1.45 0.48, 1.45
.542 .626 .623
0.76
0.57, 1.01
.06
0.60
0.37, 0.95
.031
1.49
1.11, 2.00
.008
0.87
0.54, 1.41
.580
0.24
0.13, 0.43
.000
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Table 2 (Continued)
Characteristic
History of broken hip Yes Reference: no History of diabetes Yes Reference: no Hysterectomy Yes Reference: no Osteoporosis Yes Reference: no Region Reference: Northeast Midwest South West
Odds ratio
95% confidence interval
P value
0.96
0.63, 1.47
.864
0.70
0.47, 1.06
.090
2.11
1.70, 2.62
.000
1.72
1.32, 2.24
.000
2.65 3.93 5.30
1.72, 4.08 2.50, 6.18 3.14, 8.94
.000 .000 .000
The study sample was restricted to women age 65 years or older on Medicare, not participating in managed care plans, and living in the community during the calendar year. The tabulations are weighted to account for the design effects of the MCBS. Low income represents respondents with household income 200% of the poverty line.
in our study (13.1%) is substantially lower than the 19 – 46% for the comparable age group reported in the NHEFS study cohort.6 This difference in reported rates may be due to differences in the definition of ERT use; whereas our study reported use of estrogens during the current calendar year, the NHEFS study was based on cumulative incidence (“ever used”) of ERT. Because women tend to discontinue use of estrogens, our estimates will be lower than those obtained using measures of ever-used ERT.6,9,13 The findings of lower rates of ERT use among blacks are consistent with results from previous studies.5,6,9,14 The racial difference is often interpreted as reflecting biological differences, such as the lower incidence of osteoporosis among black women. However, in our study, even after controlling for history of osteoporosis, the racial differences persisted. The low proportion of ERT use among black women could reflect slower adoption of treatment technologies by disadvantaged subgroups.15 Results from recent studies on the declining impact of race on estrogen use seem to support this.11,16 A striking finding of our study was the differences in ERT treatment patterns between specialists and generalists, perhaps because specialists tend to be more knowledgeable than generalists with respect to efficacious therapies, including appropriate pharmacotherapy.7,17–19 For example, among surveyed physicians, gynecologists believed in preventive hormone replacement therapy more strongly than family physicians and general internists, and ranked it second of eight preventive therapies.20 The lower probability of estrogen use by women with a history of breast cancer and the higher likelihood of ERT use by women with osteoporosis and heart disease most likely reflect appropriate differences in patterns of care based on current knowledge of the risks and benefits associated with ERT. However, overall, the rate of ERT treatment is quite low among women over 65, especially among women who are black, of low income, and/or who lack health insurance supplemental to Medicare. The extent to which use is 292
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determined by socioeconomic rather than medical characteristics suggests considerable inequity in access to ERT treatment. Our results suggest that the key barriers to access to ERT may be related to differences in access to physician care. Women who lack insurance supplemental to Medicare face significant out-of-pocket expenses each time they see a physician. They may be less likely to seek such care for preventive purposes rather than for the treatment of acute illnesses. Interestingly, coverage specifically for pharmaceuticals was not related to ERT use; this may reflect the mediating role of physicians’ recommendations in women’s choices. In contrast, contact with a gynecologist was strongly associated with use of ERT, suggesting that specialty sector care is an important mediating factor in ERT use. However, black race remained associated with a much lower rate of ERT use, even controlling for other socioeconomic factors as well as sector of care and health factors, indicating that cultural factors may also play important independent roles in the choice to use ERT. Some limitations to this study should be noted. This study does not capture use in the managed care sector, which is becoming an important source of health care delivery for Americans.21 In addition, we did not have the ability to assess the timing of initiation or discontinuation of ERT use or to examine the correlates of ERT at the time of initiation. There is a need for representative, longitudinal studies that can distinguish between ERT use that is initiated in late life and ERT use that is initiated earlier— eg, in the perimenopausal period—and continued into late life. Despite these limitations, our study provides important recent nationally representative data on the prevalence of ERT use among elderly Medicare beneficiaries. The study also contributes unique information about the relationship between the sector of care and estrogen use at the patient level. Our results confirm the existence of substantial socioeconomic differences in the use of ERT, even after controlling for a range of medical risk factors and health status. Although there is some evidence that socioeconomic differences in ERT use may have narrowed in recent years,11 our results suggest that substantial differences remain in access to ERT therapy among elderly women.
ACKNOWLEDGMENTS This research was supported in part by grants from the Agency for Health Care Policy and Research and the National Institute on Aging. The findings and opinions reported here are those of the authors and do not necessarily represent the views of any other individuals or organizations.
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