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ethnic disparity in mammography rates: it all depends on how you ask the question
Preventive Medicine 39 (2004) 399 – 403 www.elsevier.com/locate/ypmed
Estimating racial/ethnic disparity in mammography rates: it all depends on how you ask the question Kevin Fiscella, M.D., M.P.H., a,b,* Peter Franks, M.D., c and Sean Meldrum, M.S. a a
b
Department of Family Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA Department of Community and Preventive Medicine, University of Rochester School of Medicine and Dentistry Rochester, NY USA c Department of Family and Community Medicine, University of California School of Medicine, Davis, CA, USA Available online 20 March 2004
Abstract Background. Estimates of racial disparity in mammography appear to differ depending on the data source. This study examined the impact of different survey methodology on estimates of racial disparity in mammography. Methods. Responses from 3,090 women z40 years to two different questions from the 1996 Medical Expenditure Panel Survey (MEPS) were compared when a mammogram was last obtained versus what medical services, including mammography, were obtained over a 4month interval, aggregated across 1 year. Results. There was no significant racial disparity in 1-year mammography prevalence based on the first question (white – black difference, 3.3%; 95% confidence interval [CI], 2.5, 9.2). In contrast, a significant disparity in 1-year mammography prevalence was found based on the medical services question (difference, 13.1%; 95% CI 8.6, 17.6). Disparity estimates by Hispanic ethnicity were similar for the two questions: white – Hispanic difference, 1.6%; 95% CI 4.3, 7.5, and white – Hispanic difference 5% ( 0.2, 10.1). Adjustment for age, income, and insurance did not alter these findings. Conclusions. Estimates of racial, but not ethnic, disparities in mammography seem to depend on how the question is asked. These results caution against exclusive reliance on annual self-reports for monitoring disparities in preventive care. D 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved. Keywords: Racial stocks; Mammography; Minority groups; Ethnic groups; Blacks; Delivery of health care; Preventive health services
Introduction National surveys, such as the National Health Interview Survey (NHIS), the Medical Expenditure Panel Survey (MEPS), and the Behavioral Risk Factor Surveillance System (BRFSS) rely on self-report, primarily on an annual basis, to monitor health and health care. These surveys represent the primary means for monitoring progress toward the Health People 2010 goal of eliminating racial and ethnic disparities. They are being used to track disparities in preventive care in the annual National Healthcare Disparities Report released December, 2003 [1]. However, both NHIS and BRFSS data show minimal racial disparity in mammography screening in both younger
and older women, although socioeconomic disparities remain apparent [2,3]. In contrast, Medicare claims that data show significant racial disparity in mammography [4]. Thus, the validity of annual self-report data for assessing disparities in mammography is uncertain. In this study, we compare self-reported prevalence of mammography among white, black and Hispanic women using two different questions from the 1996 MEPS to assess whether survey administration and question wording affect estimates of disparity in mammography.
Material and methods Data source
* Corresponding author. Departments of Family Medicine, and Community and Preventive Medicine, University of Rochester School of Medicine and Dentistry, 1381 South Avenue, Rochester, NY 14620. Fax: +1-585-473-2245. E-mail address: [email protected] (K. Fiscella).
MEPS is a national survey of health care use and costs conducted by the Agency for Healthcare Research and Quality. The household component of MEPS compiled data
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Table 1 Characteristics of study sample by race and ethnicitya White, N = 2,281 Poverty status <100% Poverty line 100 – 124% Poverty line 125 – 199% Poverty line 200 – 399% Poverty line >400% Poverty line Years of educationb <12 years 12 years 13 – 15 years >15 years
Black, N = 413
Hispanic, N = 396
Dependent variable Total, N = 3,090
269 (12%) 129 (31%) 127 (32%) 110 (5%) 26 (6%) 33 (8%)
525 (17%) 169 (5%)
315 (14%)
68 (16%)
74 (19%)
457 (15%)
668 (29%) 103 (25%)
98 (25%)
869 (28%)
919 (40%)
64 (16%) 1,070 (35%)
87 (21%)
446 (20%) 149 (36%) 229 (58%) 824 (27%) 867 (38%) 145 (35%) 93 (23%) 1,105 (36%) 511 (22%) 63 (15%) 47 (12%) 621 (21%) 454 (20%) 56 (14%) 27 (7%) 537 (17%)
Patient has health insurance Yes 2,083 (91%) 352 (85%) 287 (72%) 2,722 (88%) Age group 25 – 44 45 – 64 65 – 90 a b
423 (19%) 74 (18%) 103 (26%) 600 (19%) 1,091 (48%) 219 (53%) 208 (53%) 1,518 (49%) 767 (34%) 120 (29%) 85 (21%) 972 (31%)
Results unweighted. Education was missing for three subjects.
Receipt of mammography in the past year was assessed in two ways. In the annual Household Survey conducted in 1996, women were asked ‘‘How long has it been since you had a mammogram’’? Possible responses included ‘‘Within past year’’, ‘‘Within past 2 years’’, Within past 5 years’’, ‘‘More than 5 years’’, and ‘‘Never’’. Women who reported receiving one within the past year were coded as having received a mammogram. In the Medical Events Survey, women were asked to recall any medical services, events, or procedures that they received during the prior 4 months between 1996 and 1997: ‘‘Looking at this card, which of these services, if any, did you have during the visit’’? The card listed a series of services including mammography. Women who reported a mammogram during any of the reporting periods were coded as having received a mammogram during the year. Covariates These included age in years, health care insurance (coded as insured vs. uninsured), family income (five categories based on percent of federal poverty guidelines: <100%, 100– 124%, 125 – 199%, 200 – 399%, >400%), and education (four categories: less than 12 years of education, high school diploma, some college, college degree or beyond). Statistical analysis
on 24,000 noninstitutionalized persons in 195 communities in 1996 using in-person interviews. Blacks and Hispanics were oversampled. The overall response rate was 78% [5]. Data regarding respondent demographic characteristics, health insurance, and less frequently occurring events were collected through the annual Household Survey administered in English or Spanish. Data regarding specific medical events were also collected by self-report every 4 months. Analyses were conducted on 3,090 white, black, and Hispanic women ages 40 and older. Proxy respondents and women of ‘‘other race’’ (N = 62) were excluded.
To accommodate the complex survey design of MEPS, SUDAAN was used to conduct statistical analyses (Research Triangle Park, 2001). Survey weights were used to adjust for over-sampling and nonresponse to yield population parameter estimates. Crude prevalence of mammography by race and ethnicity was estimated. Disparity in mammography prevalence based on each survey was assessed using predicted marginal effects [6]. Both crude and adjusted disparity estimates were calculated.
Independent variable
Results
Self-reported racial/ethnic identification (non-Hispanic white vs. non-Hispanic black vs. Hispanic).
The analysis was based on 3,090 white, black, and Hispanic women ages 40 years and older (Table 1). Crude
Table 2 Mammography in the previous year by race and ethnicity according to question type for women 40 and older Data source
Black prevalence (95% CI)
Hispanic prevalence (95% CI)
Annual household survey Crude 48.8% (46.4 – 51.2) Adjusteda 47.7% (45.3 – 50.1)
45.5% (40.0 – 51.0) 49.2% (43.8 – 44.6)
47.2% (41.7 – 52.8) 55.7% (49.9 – 61.6)
3.3% ( 2.5, 9.2) 1.5% ( 7.3, 4.3)
Medical events survey Crude 27.9% (25.8 – 29.9) Adjusteda 27.0% (25.0 – 29.0)
14.8% (10.6 – 19.0) 17.0% (12.6 – 21.4)
22.9% (18.3 – 27.6) 29.3% (23.5 – 35.1)
13.1% (8.6, 17.6) 10.0% (5.3, 14.7)
a
White prevalence (95% CI)
Adjusted for age, education, income, and insurance.
White – black difference (95% CI)
White – hispanic difference (95% CI) 1.6% ( 4.3, 7.5) 8.0% ( 14.3, 1.7)
5.0% ( 0.2, 10.1) 2.3% ( 8.6, 4.0)
K. Fiscella et al. / Preventive Medicine 39 (2004) 399–403
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Table 3 Mammography in the previous year by race and ethnicity according to question type for women 65 and older Data source
Black prevalence (95% CI)
Hispanic prevalence (95% CI)
White – black difference (95% CI)
White – hispanic difference (95% CI)
Annual household survey Crude rates 45.9% (42.0 – 49.7) Adjusteda 45.4% (41.6 – 49.1)
42.4% (30.5 – 54.3) 47.3% (34 – 61)
45.0% (32.9 – 57.2) 47.6% (34.9 – 60.3)
3.5% ( 8.9, 15.9) 1.9% ( 15.1, 11.2)
0.8% ( 11.9, 13.5) 2.2% ( 15.4, 10.9)
Medical events survey Crude 25.0% (21.3 – 28.7) Adjusteda 24.6% (21.0 – 28.2)
11.1% (5.0 – 17.2) 14.1% (6.7 – 21.6)
26.3% (14.7 – 37.9) 30.1% (17.5 – 42.7)
a
White prevalence (95% CI)
14.1% (7.0, 21.3) 10.5% (2.3, 18.8)
1.1% ( 13.3, 11.1) 5.5% ( 18.5, 7.6)
Adjusted for age, education, income, and insurance.
prevalence of mammography for each group, and crude and adjusted estimates of disparities in mammography are shown in Table 2. The overall unadjusted prevalence of mammography was strikingly higher in the Household Survey (49%) than the Medical Events Survey (28%). Significantly, the crude white –black disparity in prevalence is appreciably less in the Household Survey (3.3%) than in the Medical Events Survey (13.1%). In contrast, the crude white – Hispanic disparities from both surveys were less discrepant (1.6 vs. 5.0%) and in neither instance reached statistical significance. Adjustment for age, education, income, and insurance resulted in slightly lower white rates, and higher black and Hispanic rates (Table 2). However, the overall pattern remained the same as in the crude analyses. No significant disparity between blacks and whites was observed in the Household Survey ( 1.5%; 95% CI 7.3, 4.3) in contrast to the Medical Events Survey (10.0%, 95% CI 5.3, 14.7). Among Hispanics, disparities in neither survey attained statistical significance. Analyses restricted to women 65 years and older were very similar to those among women 40 and older (Table 3).
Discussion Different survey methodologies yielded strikingly different estimates of overall receipt of mammography in the past year and markedly different estimates in racial, but not ethnic, disparities in mammography. These findings raise questions regarding the validity of self-report data used to monitor disparities in preventive care for the National Healthcare Disparities Report [1]. Overall estimates of mammography screening from the annual Household Survey were nearly twofold higher than those derived from the Medical Events Survey. These discrepancies likely reflect differences in the administration of the surveys and phrasing of the survey questions. Mammography self-report validation studies show that self-report methods typically overestimate rates of mammography by as much as 40% [7– 19]. Overreporting receipt of mammography has been largely attributed to respondents’ tendency to underestimate or telescope the time that a service was last obtained [7,8,10,13– 18,20,21]. A recall interval of a year or
more that was used in the Household Survey is likely to be associated with greater telescoping or reporting error than is the 4-month recall interval used in the Medical Events Survey. Differences in wording of the questions in the two surveys may also affect overall estimates of mammography screening. In the Household Survey, respondents were specifically queried as to whether they had had a mammogram in the last year, 2 years, 3 years, etc. Given this ordered response choice and the likely impact of mammography promotional campaigns, reporting receipt of mammography within 1 year is likely to be the most socially desirable response. In contrast, there is no clear socially desirable response when reporting receipt of medical services. Because respondents are asked to identify mammography screening among 10 other medical services, this latter approach may underestimate receipt of mammography. Moreover, estimates of mammography screening from the Medical Events Survey for patients z 65 are lower than those from 1994 Medicare claims [22]. Thus, it is plausible that the actual overall rate of mammography screening falls between estimates derived from the annual Household Survey and the Medical Events Survey. The two surveys also differed in estimates of racial, but not ethnic, disparity in mammography screening. Statistically significant racial disparity in mammography screening was observed using the Medical Events Survey, but not the Household Survey. Estimates of mammography screening by race have been previously shown to be affected by question wording [23]. A change in the introductory question wording of the Behavioral Risk Factors Surveillance System between 1991 and 1992 to more clearly distinguish between chest X-rays and mammography resulted in significantly lower estimates for mammography prevalence for blacks and less educated women. There are several reasons to suspect that black women undergo mammography less often. Black women confront many barriers to obtaining mammography. These barriers include greater poverty, lower educational levels, worse health status, no insurance or absence of private insurance, not having a regular source of care, and fewer physician visits [24 – 37]. Furthermore, despite a lower incidence of breast cancer, black women have higher mortality rates attributable to breast cancer than white women [38]. African-American women are diagnosed at later stages; delays in screening have been implicated in disparities in breast
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cancer mortality [39]. Last, data from both Medicare and the Health Plan Employer Data and Information Set (HEDIS) show persistent racial disparity in mammography [40,41]. Specifically, data from 1996 to 1997 Medicare claims among women z65 years show a 9% gap between whites (43%) and blacks (34%) in receipt of mammography in the past 2 years [4]. Although it is possible that this apparent gap in Medicare mammography claims is attributable to a larger proportion of black women obtaining mammography through facilities that do not submit claims to Medicare, 1997 HEDIS data from elderly HMO enrollees that are derived from claims supplemented by chart review show comparable racial disparity in mammography [41]. Thus, Medicare claims and HEDIS data show significantly larger estimates of racial disparity in mammography than selfreport data using methodology similar to the MEPS annual Household Survey. These findings raise the possibility that reporting biases associated with race contribute to discrepancies in estimates of racial disparity in self-reported mammography. Previous studies have shown conflicting findings regarding racial differences in mammography reporting [18,20,36,42,43]. These discrepant findings may be attributable to differences in study populations and limited power. What might account for possible racial differences in reporting? African-Americans may be more likely to offer socially desirable responses to surveys [44 –48], particularly when the interviewer is white [49 – 51]. These findings may represent a type of stereotype threat or social pressure to defy stereotypes [52]. Whether Hispanics experience less social pressure in the context of reporting mammography is also unknown. These findings are subject to several limitations that merit discussion. In the absence of a gold standard, it is not clear to what extent the annual Household Survey overestimated or the Medical Events Survey underestimated overall mammography screening. Similarly, we cannot determine from these data which disparity estimate is closer to the truth. We cannot exclude the possibility that black women disproportionately underreported receipt of mammography in response to the Medical Events Survey. Conceivably, racial differences in literacy level related to use of ‘‘show cards’’ could contribute to reporting differences [53]. It is also possible that there was higher nonresponse among black women for the Medical Events Survey at the 4-month reporting intervals that was not adequately corrected through survey design weighting. Furthermore, the Medical Events Survey may have captured more diagnostic (as opposed to screening) mammograms compared to the annual survey. However, racial differences in diagnostic mammography are too modest to account for the large observed differences [54]. In contrast to many studies, we used a 1year reporting period (due to data constraints). However, racial disparity in mammography claims is slightly greater using a 2-year [55] compared to a 1-year interval [56]. Last, the recall period of the annual survey was before 1996
whereas the Medical Events recall period was 1996– 1997. However, this modest difference in recall period is unlikely to explain the marked differences in results. Despite these limitations, these findings suggest that estimates of racial, but not ethnic, disparity in self-reported mammography receipt are sensitive to question wording and survey administration. Self-report data from annual national surveys represent the primary means of monitoring progress toward the elimination of disparities in preventive care. These results caution against exclusive reliance on this approach. Studies based on large, nationally representative samples are needed to determine whether there are racial or ethnic differences in tendency to overreport receipt of mammography (or other preventive service) and whether improved question wording reduces these differences. If these findings are confirmed, improvements in survey methodology including use of shorter recall intervals, use of questions less susceptible to response bias, and explicit descriptions of mammography may help mitigate reporting biases. Acknowledgment The funding for this study was provided by the Agency for Healthcare Research and Quality (R01 HS 10295-01). References [1] AHRQ. National Healthcare Disparities Report. (available at http:// www.qualitytools.ahrq.gov/disparitiesreport/download_report.aspx, accessed 1/14/04). [2] Eberhardt MS, Ingram DD, Makuc DM. Urban and rural health chartbook, health, United States, 2001. Hyattsville, MD: National Center for Health Statistics; 2001. [3] Behavioral Risk Factor Surveillance System (available at http://apps. nccd.cdc.gov/brfss/race.asp?cat=WH&yr=2000&qkey=1984&state= US.: accessed 8/29/02). [4] Gornick ME. Disparities in medicare services: potential causes, plausible explanations, and recommendations. Health Care Financ Rev 2000;21:23 – 43. [5] Cohen S. Sample Design of the 1996 Medical Expenditure Panel Survey Household Component. Methodology Report #02 Rockville, MD, AHRQ1997. [6] Graubard BI, Korn EL. Predictive margins with survey data. Biometrics 1999;55:652 – 9. [7] Degnan D, Harris R, Ranney J, Quade D, Earp JA, Gonzalez J. Measuring the use of mammography: two methods compared. Am J Public Health 1992;82:1386 – 8. [8] Fulton-Kehoe D, Burg MA, Lane DS. Are self-reported dates of mammograms accurate? Public Health Rev 1992;20:233 – 40. [9] Brown JB, Adams ME. Patients as reliable reporters of medical care process. Recall of ambulatory encounter events. Med Care 1992;30: 400 – 11. [10] Gordon NP, Hiatt RA, Lampert DI. Concordance of self-reported data and medical record audit for six cancer screening procedures. J Natl Cancer Inst. 1993;85:566 – 70. [11] Suarez L, Goldman DA, Weiss NS. Validity of Pap smear and mammogram self-reports in a low-income Hispanic population. Am J Prev Med 1995;11:94 – 8. [12] Hiatt RA, Perez-Stable EJ, Quesenberry C, Sabogal F, Otero-Sabogal R, McPhee SJ. Agreement between self-reported early cancer detec-
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Estimating racial/ethnic disparity in mammography rates: it all depends on how you ask the question Kevin Fiscella, M.D., M.P.H., a,b,* Peter Franks, M.D., c and Sean Meldrum, M.S. a a
b
Department of Family Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA Department of Community and Preventive Medicine, University of Rochester School of Medicine and Dentistry Rochester, NY USA c Department of Family and Community Medicine, University of California School of Medicine, Davis, CA, USA Available online 20 March 2004
Abstract Background. Estimates of racial disparity in mammography appear to differ depending on the data source. This study examined the impact of different survey methodology on estimates of racial disparity in mammography. Methods. Responses from 3,090 women z40 years to two different questions from the 1996 Medical Expenditure Panel Survey (MEPS) were compared when a mammogram was last obtained versus what medical services, including mammography, were obtained over a 4month interval, aggregated across 1 year. Results. There was no significant racial disparity in 1-year mammography prevalence based on the first question (white – black difference, 3.3%; 95% confidence interval [CI], 2.5, 9.2). In contrast, a significant disparity in 1-year mammography prevalence was found based on the medical services question (difference, 13.1%; 95% CI 8.6, 17.6). Disparity estimates by Hispanic ethnicity were similar for the two questions: white – Hispanic difference, 1.6%; 95% CI 4.3, 7.5, and white – Hispanic difference 5% ( 0.2, 10.1). Adjustment for age, income, and insurance did not alter these findings. Conclusions. Estimates of racial, but not ethnic, disparities in mammography seem to depend on how the question is asked. These results caution against exclusive reliance on annual self-reports for monitoring disparities in preventive care. D 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved. Keywords: Racial stocks; Mammography; Minority groups; Ethnic groups; Blacks; Delivery of health care; Preventive health services
Introduction National surveys, such as the National Health Interview Survey (NHIS), the Medical Expenditure Panel Survey (MEPS), and the Behavioral Risk Factor Surveillance System (BRFSS) rely on self-report, primarily on an annual basis, to monitor health and health care. These surveys represent the primary means for monitoring progress toward the Health People 2010 goal of eliminating racial and ethnic disparities. They are being used to track disparities in preventive care in the annual National Healthcare Disparities Report released December, 2003 [1]. However, both NHIS and BRFSS data show minimal racial disparity in mammography screening in both younger
and older women, although socioeconomic disparities remain apparent [2,3]. In contrast, Medicare claims that data show significant racial disparity in mammography [4]. Thus, the validity of annual self-report data for assessing disparities in mammography is uncertain. In this study, we compare self-reported prevalence of mammography among white, black and Hispanic women using two different questions from the 1996 MEPS to assess whether survey administration and question wording affect estimates of disparity in mammography.
Material and methods Data source
* Corresponding author. Departments of Family Medicine, and Community and Preventive Medicine, University of Rochester School of Medicine and Dentistry, 1381 South Avenue, Rochester, NY 14620. Fax: +1-585-473-2245. E-mail address: [email protected] (K. Fiscella).
MEPS is a national survey of health care use and costs conducted by the Agency for Healthcare Research and Quality. The household component of MEPS compiled data
0091-7435/$ - see front matter D 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved. doi:10.1016/j.ypmed.2004.02.002
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Table 1 Characteristics of study sample by race and ethnicitya White, N = 2,281 Poverty status <100% Poverty line 100 – 124% Poverty line 125 – 199% Poverty line 200 – 399% Poverty line >400% Poverty line Years of educationb <12 years 12 years 13 – 15 years >15 years
Black, N = 413
Hispanic, N = 396
Dependent variable Total, N = 3,090
269 (12%) 129 (31%) 127 (32%) 110 (5%) 26 (6%) 33 (8%)
525 (17%) 169 (5%)
315 (14%)
68 (16%)
74 (19%)
457 (15%)
668 (29%) 103 (25%)
98 (25%)
869 (28%)
919 (40%)
64 (16%) 1,070 (35%)
87 (21%)
446 (20%) 149 (36%) 229 (58%) 824 (27%) 867 (38%) 145 (35%) 93 (23%) 1,105 (36%) 511 (22%) 63 (15%) 47 (12%) 621 (21%) 454 (20%) 56 (14%) 27 (7%) 537 (17%)
Patient has health insurance Yes 2,083 (91%) 352 (85%) 287 (72%) 2,722 (88%) Age group 25 – 44 45 – 64 65 – 90 a b
423 (19%) 74 (18%) 103 (26%) 600 (19%) 1,091 (48%) 219 (53%) 208 (53%) 1,518 (49%) 767 (34%) 120 (29%) 85 (21%) 972 (31%)
Results unweighted. Education was missing for three subjects.
Receipt of mammography in the past year was assessed in two ways. In the annual Household Survey conducted in 1996, women were asked ‘‘How long has it been since you had a mammogram’’? Possible responses included ‘‘Within past year’’, ‘‘Within past 2 years’’, Within past 5 years’’, ‘‘More than 5 years’’, and ‘‘Never’’. Women who reported receiving one within the past year were coded as having received a mammogram. In the Medical Events Survey, women were asked to recall any medical services, events, or procedures that they received during the prior 4 months between 1996 and 1997: ‘‘Looking at this card, which of these services, if any, did you have during the visit’’? The card listed a series of services including mammography. Women who reported a mammogram during any of the reporting periods were coded as having received a mammogram during the year. Covariates These included age in years, health care insurance (coded as insured vs. uninsured), family income (five categories based on percent of federal poverty guidelines: <100%, 100– 124%, 125 – 199%, 200 – 399%, >400%), and education (four categories: less than 12 years of education, high school diploma, some college, college degree or beyond). Statistical analysis
on 24,000 noninstitutionalized persons in 195 communities in 1996 using in-person interviews. Blacks and Hispanics were oversampled. The overall response rate was 78% [5]. Data regarding respondent demographic characteristics, health insurance, and less frequently occurring events were collected through the annual Household Survey administered in English or Spanish. Data regarding specific medical events were also collected by self-report every 4 months. Analyses were conducted on 3,090 white, black, and Hispanic women ages 40 and older. Proxy respondents and women of ‘‘other race’’ (N = 62) were excluded.
To accommodate the complex survey design of MEPS, SUDAAN was used to conduct statistical analyses (Research Triangle Park, 2001). Survey weights were used to adjust for over-sampling and nonresponse to yield population parameter estimates. Crude prevalence of mammography by race and ethnicity was estimated. Disparity in mammography prevalence based on each survey was assessed using predicted marginal effects [6]. Both crude and adjusted disparity estimates were calculated.
Independent variable
Results
Self-reported racial/ethnic identification (non-Hispanic white vs. non-Hispanic black vs. Hispanic).
The analysis was based on 3,090 white, black, and Hispanic women ages 40 years and older (Table 1). Crude
Table 2 Mammography in the previous year by race and ethnicity according to question type for women 40 and older Data source
Black prevalence (95% CI)
Hispanic prevalence (95% CI)
Annual household survey Crude 48.8% (46.4 – 51.2) Adjusteda 47.7% (45.3 – 50.1)
45.5% (40.0 – 51.0) 49.2% (43.8 – 44.6)
47.2% (41.7 – 52.8) 55.7% (49.9 – 61.6)
3.3% ( 2.5, 9.2) 1.5% ( 7.3, 4.3)
Medical events survey Crude 27.9% (25.8 – 29.9) Adjusteda 27.0% (25.0 – 29.0)
14.8% (10.6 – 19.0) 17.0% (12.6 – 21.4)
22.9% (18.3 – 27.6) 29.3% (23.5 – 35.1)
13.1% (8.6, 17.6) 10.0% (5.3, 14.7)
a
White prevalence (95% CI)
Adjusted for age, education, income, and insurance.
White – black difference (95% CI)
White – hispanic difference (95% CI) 1.6% ( 4.3, 7.5) 8.0% ( 14.3, 1.7)
5.0% ( 0.2, 10.1) 2.3% ( 8.6, 4.0)
K. Fiscella et al. / Preventive Medicine 39 (2004) 399–403
401
Table 3 Mammography in the previous year by race and ethnicity according to question type for women 65 and older Data source
Black prevalence (95% CI)
Hispanic prevalence (95% CI)
White – black difference (95% CI)
White – hispanic difference (95% CI)
Annual household survey Crude rates 45.9% (42.0 – 49.7) Adjusteda 45.4% (41.6 – 49.1)
42.4% (30.5 – 54.3) 47.3% (34 – 61)
45.0% (32.9 – 57.2) 47.6% (34.9 – 60.3)
3.5% ( 8.9, 15.9) 1.9% ( 15.1, 11.2)
0.8% ( 11.9, 13.5) 2.2% ( 15.4, 10.9)
Medical events survey Crude 25.0% (21.3 – 28.7) Adjusteda 24.6% (21.0 – 28.2)
11.1% (5.0 – 17.2) 14.1% (6.7 – 21.6)
26.3% (14.7 – 37.9) 30.1% (17.5 – 42.7)
a
White prevalence (95% CI)
14.1% (7.0, 21.3) 10.5% (2.3, 18.8)
1.1% ( 13.3, 11.1) 5.5% ( 18.5, 7.6)
Adjusted for age, education, income, and insurance.
prevalence of mammography for each group, and crude and adjusted estimates of disparities in mammography are shown in Table 2. The overall unadjusted prevalence of mammography was strikingly higher in the Household Survey (49%) than the Medical Events Survey (28%). Significantly, the crude white –black disparity in prevalence is appreciably less in the Household Survey (3.3%) than in the Medical Events Survey (13.1%). In contrast, the crude white – Hispanic disparities from both surveys were less discrepant (1.6 vs. 5.0%) and in neither instance reached statistical significance. Adjustment for age, education, income, and insurance resulted in slightly lower white rates, and higher black and Hispanic rates (Table 2). However, the overall pattern remained the same as in the crude analyses. No significant disparity between blacks and whites was observed in the Household Survey ( 1.5%; 95% CI 7.3, 4.3) in contrast to the Medical Events Survey (10.0%, 95% CI 5.3, 14.7). Among Hispanics, disparities in neither survey attained statistical significance. Analyses restricted to women 65 years and older were very similar to those among women 40 and older (Table 3).
Discussion Different survey methodologies yielded strikingly different estimates of overall receipt of mammography in the past year and markedly different estimates in racial, but not ethnic, disparities in mammography. These findings raise questions regarding the validity of self-report data used to monitor disparities in preventive care for the National Healthcare Disparities Report [1]. Overall estimates of mammography screening from the annual Household Survey were nearly twofold higher than those derived from the Medical Events Survey. These discrepancies likely reflect differences in the administration of the surveys and phrasing of the survey questions. Mammography self-report validation studies show that self-report methods typically overestimate rates of mammography by as much as 40% [7– 19]. Overreporting receipt of mammography has been largely attributed to respondents’ tendency to underestimate or telescope the time that a service was last obtained [7,8,10,13– 18,20,21]. A recall interval of a year or
more that was used in the Household Survey is likely to be associated with greater telescoping or reporting error than is the 4-month recall interval used in the Medical Events Survey. Differences in wording of the questions in the two surveys may also affect overall estimates of mammography screening. In the Household Survey, respondents were specifically queried as to whether they had had a mammogram in the last year, 2 years, 3 years, etc. Given this ordered response choice and the likely impact of mammography promotional campaigns, reporting receipt of mammography within 1 year is likely to be the most socially desirable response. In contrast, there is no clear socially desirable response when reporting receipt of medical services. Because respondents are asked to identify mammography screening among 10 other medical services, this latter approach may underestimate receipt of mammography. Moreover, estimates of mammography screening from the Medical Events Survey for patients z 65 are lower than those from 1994 Medicare claims [22]. Thus, it is plausible that the actual overall rate of mammography screening falls between estimates derived from the annual Household Survey and the Medical Events Survey. The two surveys also differed in estimates of racial, but not ethnic, disparity in mammography screening. Statistically significant racial disparity in mammography screening was observed using the Medical Events Survey, but not the Household Survey. Estimates of mammography screening by race have been previously shown to be affected by question wording [23]. A change in the introductory question wording of the Behavioral Risk Factors Surveillance System between 1991 and 1992 to more clearly distinguish between chest X-rays and mammography resulted in significantly lower estimates for mammography prevalence for blacks and less educated women. There are several reasons to suspect that black women undergo mammography less often. Black women confront many barriers to obtaining mammography. These barriers include greater poverty, lower educational levels, worse health status, no insurance or absence of private insurance, not having a regular source of care, and fewer physician visits [24 – 37]. Furthermore, despite a lower incidence of breast cancer, black women have higher mortality rates attributable to breast cancer than white women [38]. African-American women are diagnosed at later stages; delays in screening have been implicated in disparities in breast
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cancer mortality [39]. Last, data from both Medicare and the Health Plan Employer Data and Information Set (HEDIS) show persistent racial disparity in mammography [40,41]. Specifically, data from 1996 to 1997 Medicare claims among women z65 years show a 9% gap between whites (43%) and blacks (34%) in receipt of mammography in the past 2 years [4]. Although it is possible that this apparent gap in Medicare mammography claims is attributable to a larger proportion of black women obtaining mammography through facilities that do not submit claims to Medicare, 1997 HEDIS data from elderly HMO enrollees that are derived from claims supplemented by chart review show comparable racial disparity in mammography [41]. Thus, Medicare claims and HEDIS data show significantly larger estimates of racial disparity in mammography than selfreport data using methodology similar to the MEPS annual Household Survey. These findings raise the possibility that reporting biases associated with race contribute to discrepancies in estimates of racial disparity in self-reported mammography. Previous studies have shown conflicting findings regarding racial differences in mammography reporting [18,20,36,42,43]. These discrepant findings may be attributable to differences in study populations and limited power. What might account for possible racial differences in reporting? African-Americans may be more likely to offer socially desirable responses to surveys [44 –48], particularly when the interviewer is white [49 – 51]. These findings may represent a type of stereotype threat or social pressure to defy stereotypes [52]. Whether Hispanics experience less social pressure in the context of reporting mammography is also unknown. These findings are subject to several limitations that merit discussion. In the absence of a gold standard, it is not clear to what extent the annual Household Survey overestimated or the Medical Events Survey underestimated overall mammography screening. Similarly, we cannot determine from these data which disparity estimate is closer to the truth. We cannot exclude the possibility that black women disproportionately underreported receipt of mammography in response to the Medical Events Survey. Conceivably, racial differences in literacy level related to use of ‘‘show cards’’ could contribute to reporting differences [53]. It is also possible that there was higher nonresponse among black women for the Medical Events Survey at the 4-month reporting intervals that was not adequately corrected through survey design weighting. Furthermore, the Medical Events Survey may have captured more diagnostic (as opposed to screening) mammograms compared to the annual survey. However, racial differences in diagnostic mammography are too modest to account for the large observed differences [54]. In contrast to many studies, we used a 1year reporting period (due to data constraints). However, racial disparity in mammography claims is slightly greater using a 2-year [55] compared to a 1-year interval [56]. Last, the recall period of the annual survey was before 1996
whereas the Medical Events recall period was 1996– 1997. However, this modest difference in recall period is unlikely to explain the marked differences in results. Despite these limitations, these findings suggest that estimates of racial, but not ethnic, disparity in self-reported mammography receipt are sensitive to question wording and survey administration. Self-report data from annual national surveys represent the primary means of monitoring progress toward the elimination of disparities in preventive care. These results caution against exclusive reliance on this approach. Studies based on large, nationally representative samples are needed to determine whether there are racial or ethnic differences in tendency to overreport receipt of mammography (or other preventive service) and whether improved question wording reduces these differences. If these findings are confirmed, improvements in survey methodology including use of shorter recall intervals, use of questions less susceptible to response bias, and explicit descriptions of mammography may help mitigate reporting biases. Acknowledgment The funding for this study was provided by the Agency for Healthcare Research and Quality (R01 HS 10295-01). References [1] AHRQ. National Healthcare Disparities Report. (available at http:// www.qualitytools.ahrq.gov/disparitiesreport/download_report.aspx, accessed 1/14/04). [2] Eberhardt MS, Ingram DD, Makuc DM. Urban and rural health chartbook, health, United States, 2001. Hyattsville, MD: National Center for Health Statistics; 2001. [3] Behavioral Risk Factor Surveillance System (available at http://apps. nccd.cdc.gov/brfss/race.asp?cat=WH&yr=2000&qkey=1984&state= US.: accessed 8/29/02). [4] Gornick ME. Disparities in medicare services: potential causes, plausible explanations, and recommendations. Health Care Financ Rev 2000;21:23 – 43. [5] Cohen S. Sample Design of the 1996 Medical Expenditure Panel Survey Household Component. Methodology Report #02 Rockville, MD, AHRQ1997. [6] Graubard BI, Korn EL. Predictive margins with survey data. Biometrics 1999;55:652 – 9. [7] Degnan D, Harris R, Ranney J, Quade D, Earp JA, Gonzalez J. Measuring the use of mammography: two methods compared. Am J Public Health 1992;82:1386 – 8. [8] Fulton-Kehoe D, Burg MA, Lane DS. Are self-reported dates of mammograms accurate? Public Health Rev 1992;20:233 – 40. [9] Brown JB, Adams ME. Patients as reliable reporters of medical care process. Recall of ambulatory encounter events. Med Care 1992;30: 400 – 11. [10] Gordon NP, Hiatt RA, Lampert DI. Concordance of self-reported data and medical record audit for six cancer screening procedures. J Natl Cancer Inst. 1993;85:566 – 70. [11] Suarez L, Goldman DA, Weiss NS. Validity of Pap smear and mammogram self-reports in a low-income Hispanic population. Am J Prev Med 1995;11:94 – 8. [12] Hiatt RA, Perez-Stable EJ, Quesenberry C, Sabogal F, Otero-Sabogal R, McPhee SJ. Agreement between self-reported early cancer detec-
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