Differences in Diabetes Prevalence, Incidence, and Mortality Among the Elderly of Four Racial/Ethnic Groups: Whites, Blacks, Hispanics, and Asians

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1 Epidemiology/Health Services/Psychosocial Research O R I G I N A L A R T I C L E Differeces i Diabetes Prevalece, Icidece, ad Amog the Elderly of Four Racial/Ethic Groups: Whites, Blacks, Hispaics, ad Asias A. MARSHALL MCBEAN, MD, MSC 1 SHULING LI, MS 2 2 DAVID T. GILBERTSON, PHD ALLAN J. COLLINS, MD 2,3 OBJECTIVE To examie diabetes prevalece, icidece, ad mortality from 1993 to 2001 amog fee-for-service Medicare beeficiaries 67 years of age. RESEARCH DESIGN AND METHODS This study was a retrospective aalysis of a 5% radom sample of Medicare fee-for-service beeficiaries 65 years of age i each year. RESULTS I 1993, the prevalece of diabetes amog those 67 years of age was 145 cases per 1,000 idividuals. By 2001, it was 197/1,000, a icrease of 36.0%. The 2001 prevalece amog Hispaics (334/1,000) was sigificatly higher tha amog blacks (296/1,000), Asias (243/1,000), ad whites (184/1,000, P ). Durig the 7-year period the greatest icrease i diabetes prevalece was amog Asias (68.0%). Betwee 1994 ad 2001, the aual of ewly diagosed elderly idividuals with diabetes icreased by 36.9%. Hispaics had the greatest icrease at 55.0%. The mortality amog idividuals with diabetes decreased by 5% betwee 1994 ad 2001 from 92.1/1,000 to 87.2/1,000 (P 0.001), due to a 6% decrease amog whites. No decrease i mortality was see amog elderly idividuals without diabetes, it was 55/1,000 i 1994 ad 54/1,000 i CONCLUSIONS The dramatic icrease i the icidece ad prevalece of diabetes likely reflect a combiatio of true icreases, as well as chages i the diagostic criteria ad icreased iterest i diagosig ad appropriately treatig diabetes i the elderly. Improved treatmet may have had a impact o mortality s amog idividuals with diabetes, although they could have bee iflueced by the duratio of diabetes before diagosis, which has likely decreased. Chages i icidece, prevalece, ad mortality i elderly idividuals with diabetes eed to cotiue to be moitored. The umber of idividuals reported to have diabetes i the U.S. has icreased by 100% over the past two decades, ad by 2050, it is expected to icrease by a additioal 165% (1 6). Diabetes Care 27: , 2004 The curret burde of diabetes is greatest i the populatio 65 years of age (1 4,7 9), ad the greatest icreases i prevalece are expected amog the elderly: from 252% amog wome years of From the 1 Divisio of Health Services Research ad Policy, Uiversity of Miesota School of Public Health, Mieapolis, Miesota; the 2 Nephrology Aalytic Services, Heepi Couty Medical Ceter, Mieapolis, Miesota; ad the 3 Departmet of Medicie, Uiversity of Miesota School of Medicie, Mieapolis, Miesota. Address correspodece ad reprit requests to A. Marshall McBea, MD, MSc, Divisio of Health Services Research ad Policy, Uiversity of Miesota School of Public Health, MMC 97, Mayo Memorial Buildig, 420 Delaware St. SE, Mieapolis, MN mcbea002@um.edu. Received for publicatio 17 March 2004 ad accepted i revised form 17 July Abbreviatios: BRFSS, Behavioral Risk Factor Surveillace System; CDC, Ceters for Disease Cotrol ad Prevetio; DSS, Diabetes Surveillace System; HHA, Home Health Agecy; MCBS, Medicare Curret Beeficiary Survey; NHANES, Natioal Health ad Nutritio Examiatio Survey; SNF, Skilled Nursig Facility; VA, Departmet of Veteras Affairs. A table elsewhere i this issue shows covetioal ad Système Iteratioal (SI) uits ad coversio factors for may substaces by the America Diabetes Associatio. age to 537% amog me 75 years of age (6). A explicit goal of Healthy People 2010 ad the Presidet s Iitiative o Racial ad Ethic Disparities is to elimiate racial disparities i health ad health care by 2010 (9,10). Objective 5-3 of Healthy People 2010 is to reduce the overall of diabetes that is cliically diagosed. Thus, it is importat that the prevalece ad icidece of diabetes be moitored durig this decade amog idividuals of all racial/ethic groups, particularly those kow to have higher s of diabetes: blacks, Hispaics, ad Native Americas. The Medicare admiistrative data available from the Ceters for Medicare ad Medicaid Services are atioal populatio-based databases that have bee used to determie the prevalece of diabetes i the U.S. elderly populatio (11 13). The purpose of this work is to describe the prevalece ad ewly diagosed cases of diabetes amog Medicare elderly beeficiaries i the years , as well as mortality s amog idividuals with diabetes. Comparisos are made betwee four racial/ethic groups (whites, blacks, Hispaics, ad Asias), five age-groups, ad both sexes. RESEARCH DESIGN AND METHODS For evaluatig subjects durig the period 1992 through 2001, we used the followig aual 5% Medicare erollmet ad claims-based files: Deomiator, Hospital Ipatiet, Skilled Nursig Facility (SNF), Carrier, Outpatiet, ad Home Health Agecy (HHA). Approximately 98% of the U.S. populatio aged 65 years is erolled i Medicare. The 5% Medicare files iclude iformatio o a 5% radom sample of beeficiaries. The Deomiator files provided demographic iformatio ad Medicare ad maaged care erollmet status. The Carrier file cotais records based o claims submitted by physicias DIABETES CARE, VOLUME 27, NUMBER 10, OCTOBER

2 Diabetes ad race/ethicity ad other oistitutioal providers of care. The iformatio captured from the five claims-based files icluded diagoses ad dates of service. Idetificatio of idividuals with diabetes The diagosis codes i the Ipatiet, SNF, Carrier, Outpatiet, ad HHA files were searched for 2 years (e.g., 1992 ad 1993) to determie the prevalece of cases of diabetes at the ed of the 2-year period (i.e., o 31 December 1993, etc.). We have previously validated this method (11). We searched all diagosis positios i the claims files for ICD-9-CM codes 250.XX, diabetes; 357.2, diabetic ephropathy; , diabetic retiopathy; ad , diabetic cataract. Ay perso with oe hospitalizatio, oe SNF stay, oe HHA record, two Outpatiet visits, or two Carrier lie item records with oe of the diagoses was idetified as havig diabetes. For the Outpatiet claims ad the Carrier lie items, the services must have bee provided o differet days. This method has a sesitivity of 0.75, a specificity of 0.97, ad a positive predictive value of 0.88 compared with self-reported diabetes (11). The 2-year search meas that our estimates ca oly be made for those idividuals who are 67 years of age. Exclusio criteria We excluded idividuals 1) who did ot have both Medicare Part A ad Part B coverage durig ay time durig the period used to defie a case (they were excluded because they would have o claims for oe or more of the files icluded i our case-fidig algorithm; this resulted i a loss of 6% of the populatio [14]); 2) who had bee diagosed with ed-stage real disease durig the aalysis period; 3) who did ot reside i the 50 states, DC, or Puerto Rico; ad 4) who beloged to a maaged care orgaizatio durig the study period. This is doe routiely i studies of Medicare beeficiaries usig claims data because o claims are submitted for Medicare Part B services. Durig the period of our study, 4% (1992) to 16% (1999) of the Medicare populatio was erolled i maaged care. Codig of race/ethicity The Medicare race variable is a sigle byte. Thus, Hispaic is treated as a race ad ot a ethicity, ad Medicare beeficiaries must choose betwee Hispaic ad white, black, etc. Statistical aalysis For each year, the crude ad adjusted diabetes prevalece ad the percetage of the populatio with ewly diagosed diabetes (icidece) were calculated, as was the mortality for each caledar year s prevalece cohort. The deomiator for the prevalece calculatios was the populatio alive o 31 December 199X or 200X. The deomiators for the icidece calculatios were the beeficiaries without diabetes alive o 1 Jauary 199X or 200X who cotiued their Part A ad B coverage. The deomiators for the mortality calculatios were the beeficiaries with diabetes, or without diabetes, alive o 1 Jauary 199X or 200X. Direct adjustmet was used to calculate the adjusted prevalece of diabetes, with the % Medicare populatio as the referece. A logistic regressio model was used to estimate the predicted 1-year icidece s of diabetes, with age, sex, ad race/ ethicity as covariates. Usig modelbased adjustmet, ad with the % Medicare populatio as the referece, these s were further adjusted for the same covariates. Adjusted 1-year death s were obtaied followig the same method. Comparisos of adjusted prevalece s of diabetes betwee differet demographic groups were doe usig the z statistic. For icidece s of diabetes ad death s, a logistic regressio model was used for testig the differeces i the adjusted s betwee differet demographic groups. Comparisos of s for differet years withi a demographic group were doe usig the bootstrap method with 1,000 iteratios (15,16). All aalyses were performed usig SAS versio 8.2 (SAS, Cary, NC). RESULTS The estimated adjusted prevalece of diabetes i the elderly Medicare populatio o 31 December 1993 was 145 cases per 1,000 idividuals (Table 1 ad Fig. 1). It icreased to 197/ 1,000 i 2001, a 36.0% icrease, represetig 4,532,520 idividuals with diabetes. The highest prevalece was see amog miority groups. Hispaics ad blacks had the highest prevalece i all years. It icreased from 241/1,000 ad 222/1,000, respectively, i 1993, to 334/ 1,000 ad 296/1,000, respectively, i Throughout the period the prevalece was % greater amog Hispaics tha amog blacks (P ). The greatest percetage icrease i prevalece was see amog Asias. Betwee 1993 ad 2001 their adjusted prevalece wet from 144/1,000, a similar to that of whites (135/1,000, P 0.157), to 243/1,000, a 68.0% icrease. Prevalece icreased with age, peakig amog those years of age (211/1,000 i 2001) ad the decreasig. Betwee 1994 ad 2001, the umber of idividuals aged 67 years ewly diagosed with diabetes each year icreased from 544,140 to 660,240 (Table 2). The adjusted icidece icreased from 27/1,000 i 1994 to 37/1,000 i 2001, a 36.9% icrease. The highest s of ewly diagosed cases of diabetes were see amog the miority groups, also. Compared with whites, for all years the icidece amog Hispaics, blacks, ad Asias were 90 to 140, 53 to 60, ad 26 to 48% greater, respectively. Betwee 1994 ad 2001, the umber of idividuals with diabetes aged 67 years who died each year icreased from 300,540 to 359,480 (Table 3). However, the mortality, which was essetially uchaged from 1994 to 1999 at 92/ 1,000, decreased to 90/1,000 i 2000 (data ot show) ad was 87.2/1,000 i 2001, or 95% of the 1994 (P 0.001). The highest adjusted mortality s i 2001 were amog blacks ad whites, 91.7/1,000 ad 87.7/1,000, respectively, a osigificat differece (P 0.13). s amog the other two miority groups were sigificatly lower tha those amog whites, 72.5/1,000 amog Hispaics ad 56.3/ 1,000 amog Asias. Betwee 1994 ad 2001, the 6% decrease amog whites was statistically sigificat (P 0.001). The 21% decrease amog Asias was ot (P 0.262). There was o chage amog blacks or Hispaics. The age-group specific mortality s icreased with age from 40/1,000 i those idividuals with diabetes years of age to slightly 200/1,000 i those 85 years of age i If the age-group iformatio i Table 3 is combied ito larger groups i order to be more similar to other published iformatio, there is a approximate doublig of the mortality for each additioal decade. For example, i 2001, the uad DIABETES CARE, VOLUME 27, NUMBER 10, OCTOBER 2004

3 McBea ad Associates justed mortality amog those years of age was 46/1,000; amog those years of age, it was 90/1,000; ad amog those 85 years of age, it was 203/ 1,000 (data ot show). The estimated adjusted 1-year mortality amog elderly Medicare beeficiaries without diabetes i 1994 was 55/ 1,000, ad it remaied essetially uchaged for the ext 7 years (Table 3). As with idividuals with diabetes, the highest adjusted mortality s were amog blacks ad whites. For example, i 2001, they were 61/1,000 ad 54/1,000, respectively. CONCLUSIONS Reports of the cotiuig icrease i the prevalece of diabetes amog elderly Americas are ot ew (2 7). What is of cocer is that i 2001 the highest prevalece ad icidece were see amog the miority groups we studied ad that the highest s of icreases were amog Hispaics ad Asias. The prevalece iformatio we preset o the elderly Medicare fee-forservice populatio is cosistet with iformatio reported by the Diabetes Surveillace System (DSS) ad the Behavioral Risk Factor Surveillace System (BRFSS) of the Natioal Ceters for Disease Cotrol ad Prevetio (CDC) (3,4). I 2001, the DSS estimated prevalece s of 164/1,000 ad 139/1,000 for the age-groups years ad 75, respectively, represetig icreases of 56.4 ad 34.0% betwee 1993 ad The prevalece of diabetes amog idividuals aged 65 years reported by the BRFSS for the media state was 116/1,000 i 1993 ad 149/1,000 i 2001, a icrease of 28.4%. The most recet iformatio from the Natioal Health ad Nutritio Examiatio Survey (NHANES) idicates a slower growth i self-reported diabetes (19.7%) from 127/1,000 i to 152/1,000 i i idividuals aged 60 years (17). All of these surveys exclude istitutioalized idividuals, which would bias their estimates dowward compared with ours. Iformatio from the Medicare Curret Beeficiary Survey (MCBS) idicated that the self-reported of diabetes amog commuity-dwellig Medicare beeficiaries for was betwee 0.79 ad 0.96 of the i the istitutioalized beeficiaries (18). Oe uaswered questio is how All s are adjusted usig the 2000 populatio. The age categories i the stadard populatio are 67 69, 70 74, 75 79, 80 84, ad 85 years old. The race/ethicity categories are white, black, Hispaic, Asia, ad other/ukow. Total s are adjusted for age, sex, ad race/ethicity; s by age for sex ad race/ethicity; s by sex for age ad race/ethicity; ad s by race/ethicity for age ad sex. * idicates the umber of idividuals with diabetes alive o 31 December 199X or 2001; P betwee adjusted i 1993 ad adjusted i 2001; P ad P 0.01 betwee adjusted for referece demographic subgroup i 199X or 2001 ad the demographic subgroup i that lie. Total 3,476, ,680, ,787, ,050, ,532, Age (years) , , , , , ,056, ,114, ,121, ,156, ,269, (ref.) 841, , , ,058, ,173, , , , , , , , , , , Sex Male (ref.) 1,398, ,482, ,552, ,673, ,907, Female 2,078, ,197, ,235, ,376, ,624, Race/ethicity White (ref.) 2,944, ,096, ,145, ,357, ,749, Black 409, , , , , Hispaic 42, , , , , Asia 9, , , , , Prevalece Prevalece Prevalece Prevalece Prevalece Percet icrease: 1993 to 2001 Table 1 Estimated umber ad adjusted prevalece of diabetes per 1,000 Medicare elderly fee-for-service beeficiaries, selected years * DIABETES CARE, VOLUME 27, NUMBER 10, OCTOBER

4 Diabetes ad race/ethicity Figure 1 Prevalece (upper series) ad icidece (lower series) of diabetes per 1,000 elderly Medicare beeficiaries, much the reported icreases i prevalece ad icidece usig the Medicare databases, DSS, ad BRFSS reflect true icreases versus other factors. The NHANES iformatio, cited earlier, idicated that the 19.7% icrease i selfreported diabetes prevalece was accompaied by a decrease i udiagosed diabetes, resultig i the total prevalece for the two periods beig similar, 190/ 1,000 i ad 193/1,000 i (17). However, as poited out i the Editorial Note of that report, the lack of icrease i prevalece is uexpected i light of the icreasig prevalece of obesity ad overweight i U.S. adults documeted by the NHANES. Also, because a oral glucose tolerace test was ot performed i NHANES , the survey does ot capture the additioal proportio of Table 2 Estimated umber ad adjusted of idividuals with ewly diagosed diabetes per 1,000 Medicare elderly fee-for-service beeficiaries without diabetes, selected years * Rate Rate Rate Rate Rate Percet icrease: 1994 to 2001 Total 544, , , , , Age (years) , , , , , , , , , , (ref.) 125, , , , , , , , , , , , , , , Sex Male (ref.) 234, , , , , Female 310, , , , , Race/ethicity White (ref.) 470, , , , , Black 55, , , , , Hispaic 6, , , , , Asia 2, , , , , All s are adjusted usig the 2000 populatio. The age categories i the stadard populatio are 67 69, 70 74, 75 79, 80 84, ad 85 years old. The race/ethicity categories are white, black, Hispaic, Asia, ad other/ukow. Total s are adjusted for age, sex, ad race/ethicity; s by age for sex ad race/ethicity; s by sex for age ad race/ethicity; ad s by race/ethicity for age ad sex. * idicates the umber of idividuals with ewly diagosed diabetes durig 1999X or 2001; P betwee adjusted i 1994 ad adjusted i 2001; P ad P betwee adjusted for referece demographic subgroup i 199X or 2001 ad the demographic subgroup i that lie DIABETES CARE, VOLUME 27, NUMBER 10, OCTOBER 2004

5 McBea ad Associates Table 3 Number of deaths ad adjusted 1-year all-cause mortality s per 1,000 elderly Medicare fee-for-service beeficiaries with diabetes ad those without diabetes, selected years * Ratio: 2001 to 1994 Idividuals with diabetes Total 300, , , , , Age (years) (ref.) 27, , , , , , , , , , , , , , , , , , , , , , , , , Sex Male (ref.) 130, , , , , Female 169, , , , , Race White (ref.) 258, , , , , Black 32, , , , , Hispaic 2, , , , , Asia , , , Idividuals without diabetes Total 1,062, ,079, ,054, ,013, , Age (years) (ref.) 83, , , , , , , , , , , , , , , , , , , , , , , , , Sex Male (ref.) 487, , , , , Female 575, , , , , Race/ethicity White (ref.) 958, , , , , Black 79, , , , , Hispaic 4, , , , , Asia 2, , , , , All s are adjusted usig the 2000 populatio. The age categories i the stadard populatio are 67 69, 70 74, 75 79, 80 84, ad 85 years old. The race/ethicity categories are white, black, Hispaic, Asia, ad other/ukow. Total s are adjusted for age, sex, ad race/ethicity; s by age for sex ad race/ethicity; s by sex for age ad race/ethicity; ad s by race/ethicity by age ad sex. * idicates the umber of deaths amog idividuals with diabetes i 31 December 199X or 2001; P ad P 0.01 betwee adjusted i 1994 ad adjusted i 2001; P , P 0.001, ad P 0.01 betwee adjusted for referece demographic subgroup i 199X or 2001 ad the demographic subgroup i that lie. people with ormal fastig glucose levels who have abormal postload glucose tolerace, which i the previous NHANES had raised the prevalece of glucose itolerace by 36% (19). Egelgau et al. (20) from CDC recetly icluded chagig diagostic criteria ad improved or ehaced detectio i their reasos for the uptred i self-reported prevalece. Supportig their cotetio is the July 1997 recommedatio of ew criteria for the diagosis of diabetes by The Expert Committee o the Diagosis ad Classificatio of Diabetes Mellitus (21) ad the results of the U.K. Prospective Diabetes Study i 1998 (22). The former reduced the fastig plasma glucose level required for the diagosis of diabetes from 140 to 125 mg/dl. The latter provided cliicias with radomized trial iformatio that the aggressive treatmet of idividuals with type 2 diabetes could delay or prevet the oset of microvascular complicatios of diabetes. Thus, they would be more motivated to idetify idividuals at risk of diabetes earlier because they had available, effective treatmet. Comparisos of the average aual icreases i prevalece ad icidece i the Medicare elderly (Tables 1 ad 2 ad Fig. 1) durig the period 1993 (or 1994 for icidece) through 1996 with the period 1997 through 2001 show greater icreases i the latter period. The average icrease i prevalece from 1996 to 2001 was 8/1,000, twofold greater tha that of the period from 1993 to 1996 (4.0/1,000). Similarly, the aual icrease i icidece for the latter period was 1.7/1,000, DIABETES CARE, VOLUME 27, NUMBER 10, OCTOBER

6 Diabetes ad race/ethicity 2.65 times greater tha that of the period from 1994 to 1996 (0.6/1,000). The DSS ad BRFSS also show greater average aual icreases i the prevalece of selfreported diabetes from 1996 (BRFSS) ad 1997 (DSS) through 2001, for the total adult populatio ad the elderly, respectively (3,4). We foud the greatest icrease i prevalece amog Hispaics (38.5%) ad Asias (68.0%). There are little published data with which to compare this tred iformatio. The DSS bega reportig prevalece iformatio for Hispaics begiig i 1997, but o iformatio is yet provided for Asias. Our prevalece estimate for Hispaics i 2001 (334/1,000) is 39.7% greater tha a estimate of 239/ 1,000 for Hispaics, which ca be made from the DSS iformatio (3). Our fidig of a greater prevalece is likely because the populatio of Hispaic Medicare beeficiaries is differet from the Hispaic populatio icluded i the Natioal Health Iterview Survey used by the DSS. The vast majority of Medicare beeficiaries ear the etitlemet to Medicare by workig 40 quarters i jobs for which Medicare taxes are paid. Thus, Hispaics i the Medicare program are more likely to have lived i the U.S. for a loger period of time o average tha those who are sampled i the Natioal Health Iterview Survey, which is based o the curret place of residece. This could cotribute to a higher true prevalece due to the adoptio of a more westerized lifestyle (23 25), as well as a icreased opportuity to be diagosed by a health care provider because of greater access to health care amog those who are Medicare beeficiaries. The dramatic icrease of diabetes amog Asia Americas was probably due to similar factors. Studies have documeted icreased s of diabetes amog Asia-America immigrats (23 25) related to the duratio of time i the U.S. ad a westerizatio of their lifestyle, particularly i diet. A recet study of East Coast Japaese immigrats, described as less accultud ewcomers tha other Japaese, reported a prevalece of diabetes i the adult Japaese Americas that was oly two-thirds that of all adults i the area (46/1,000 vs. 68/ 1,000, respectively) (26). The difficulty of determiig a atioal estimate of the mortality amog idividuals with diabetes has bee discussed (1). A stregth of the Medicare databases is kowledge of the date of death of beeficiaries. This iformatio must be reported to the Social Security Admiistratio for deceased beeficiaries, ad the Social Security Admiistratio provides that iformatio to Ceters for Medicare ad Medicaid Services. The lower mortality s amog Hispaics ad Asias with diabetes tha amog whites ad blacks are cosistet with the lower mortality s we foud amog those without diabetes, reports of allcause mortality reported by the Natioal Ceter for Health Statistics (27), ad the recet report of Bertoi et al. usig Medicare data from 1995 to 1999 (28). We foud that the oly sigificat decrease i mortality amog idividuals with diabetes of the differet racial/ethic groups was amog whites. The possible reasos for this, such as better access to diabetes care, are outside the scope of this study ad should be followed up. I a report to the CDC, we foud higher s of HbA 1c testig ad eye examiatio i 1994 amog white, fee-for-service, elderly Medicare beeficiaries tha amog blacks ad the other ethicity groups combied (12). We, ad others, have also reported that elderly whites erolled i Medicare maaged care plas are more likely to receive recommeded diabetes care ad have lower s of poor HbA 1c cotrol tha either blacks or Hispaics (29 32). The icreased risk of death amog idividuals with diabetes compared with idividuals without diabetes is well documeted (1,3,22,28). We foud the overall risk of dyig amog elderly Medicare beeficiaries to be 1.6 times greater tha the amog idividuals without diabetes. This is cosistet with the ratio of 1.5 preseted by Gu et al. (33) for idividuals years of age i 1971 ad the ratio of 1.6 foud by Bertoi et al. (28) for Based o iformatio i Table 11.1 i Diabetes i America, racespecific ratios of 2.2 for whites ad 1.4 for blacks ca be estimated for 1986 (1). Our estimates for 2001 are 1.6 ad 1.5, respectively (Table 3). Our ratios i 2001 for Hispaics ad Asias were 1.7 ad 1.5, respectively. The stregth of this study lies i the large umber of idividuals available for moitorig, eve i the 5% sample of Medicare beeficiaries. We have bee able to produce estimates for more agegroups tha usually described i other atioal data, as well as a additioal racial/ethic group (Asias). Because of the sample size, we did ot have to average our data over a 3-year period, as is doe by the DSS. Also, comparisos with DSS data show a much greater stability i our estimates amog the miority populatios. Potetial weakesses iclude the misclassificatio of diabetes ad of race/ ethicity amog some beeficiaries. Claims-based aalyses of diabetes epidemiology will result i a certai amout of misclassificatio of cases. Our earlier study that described ad validated the algorithm we used, ad that has bee used by others, idicated a sesitivity of 0.75, specificity of 0.97, ad a positive predictive value of 0.84 usig 1991 ad 1992 claims data (11). Thus, our estimated prevalece will be less tha the true value, assumig that self-reported diabetes (which is what we used for the gold stadard) is truly a gold stadard. However, with the very high positive predictive value, the great majority of those idetified as havig diabetes have the disease. Aother issue that could impact a logitudial study such as ours is a chage i the sesitivity of the measuremet method (as happeed with the Natioal Health Iterview Survey i 1997 [3]) that would icrease or decrease the accuracy of the iformatio. To verify the accuracy of our measuremet method, we repeated the Hebert et al. (11) study. We foud that compared with , the sesitivity of the claims-based algorithm usig 2000 ad 2001 claims data had icreased by slightly 25% to Thus, approximately oe-fourth of the 36% icrease i prevalece that we report may be due to this improvemet i the algorithm to detect idividuals with diabetes. Arday et al. (34) validated the Medicare race variable usig admiistrative data ad self-reported MCBS iformatio from While the sesitivity for whites ad blacks was very high (0.97 ad 0.95, respectively), it was 0.39 ad 0.58 for Hispaics ad Asias, respectively. The positive predictive value was 0.96 for whites, blacks, ad Hispaics ad 0.79 for Asias. Thus, idividuals idetified as a particular race/ethicity had a very high probability of that beig correct. Because the race/ethicity iformatio has bee cotiuously updated by Medicare, this is likely to have improved 2322 DIABETES CARE, VOLUME 27, NUMBER 10, OCTOBER 2004

7 McBea ad Associates the accuracy over that reported by Arday et al. Fially, icludig oly those who use Medicare-reimbursed services limits the geeralizability of the results to all elderly Americas. The largest groups we excluded are those i Medicare maaged care (4 16%, aually), those who use the Departmet of Veteras Affairs (VA) services, ad those without Medicare Part B coverage. The MCBS, which icludes Medicare beeficiaries i maaged care, estimated the prevalece of self-reported diabetes amog all beeficiaries aged 65 years i 2000 as 177/1,000 compared with our estimate of 189/1,000 i those aged 67 years (18), idicatig that Medicare beeficiaries i maaged care likely have lower s of diabetes ad would lower our prevalece estimates if they could be icluded. Most VA patiets 65 years of age are eligible for Medicare, ad the majority of VA patiets use o-va services for part or all of their health care, so they would likely be icluded i our cases (35 37). O the other had, there is a ukow percetage of the Medicare-eligible elderly, particularly me, who use VA services exclusively. Because the of diabetes is higher amog VA users (7,38), their exclusio reduced our icidece ad prevalece estimates. I summary, we have documeted major icreases i the prevalece ad icidece i all 5-year age-groups, i both sexes, ad amog the racial/ethic groups white, black, Hispaic, ad Asia betwee the early 1990s ad The greatest icreases were see amog two miority populatios: Hispaics ad Asias. The two groups with the highest prevalece, blacks ad Hispaics, are the two i which there was o idicatio of a possible decrease i mortality. Ackowledgmets This work was supported by the Natioal Istitute of Diabetes ad Digestive ad Kidey Diseases (NIDDK) uder R21 DK Jiaog Liu performed the bootstrappig. Refereces 1. Harris MI, Cowie CC, Ster MP, Boyko EJ, Reiber GE, Beet PH (Eds.): Diabetes i America. 2d ed. Washigto, DC, U.S. Departmet of Health ad Huma Services, Natioal Istitutes of Health, 1995 (DHHS publ. o. [NIH] ) 2. Ceters for Disease Cotrol ad Prevetio: Diabetes Surveillace, Atlata, GA, U.S. Departmet of Health ad Huma Services, Diabetes Surveillace System [Iteret]. Available from diabetes/statistics/idex.htm. Accessed 8 July Behavioral Risk Factor Surveillace System [Iteret]. Available from Accessed 8 July Mokdad AH, Ford ES, Bowma BA, Nelso DE, Egelgau MM, Viicor F, Marks JS: Diabetes treds i the U.S.: Diabetes Care 23: , Boyle JP, Hoeycutt AA, Vekat Naraya KM, Hoerger TJ, Geiss LS, Che H, Thompso TJ: Projectio of diabetes burde through Diabetes Care 24: , Miller Dr, Safford MM, Pogach LM: Who has diabetes? Best estimates if diabetes prevalece i the Departmet of Veteras Affairs based i computerized patiet data. 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8 Diabetes ad race/ethicity beeficiaries. A Epidemiol 14: , Scheider EC, Zaslavsky AM, Epstei AM: Racial disparities i the quality of care for erollees i Medicare maaged care. JAMA 287: , Virig BA, Lurie N, Huag Z, Musgrave D, McBea AM, Dowd B, Racial variatio i quality of care amog Medicare Choice erollees. Health Affairs 21: , McBea AM: Huag Z, Virig BA, Lurie N, Musgrave D: Racial variatio i the cotrol of diabetes amog elderly Medicare maaged care beeficiaries. Diabetes Care 26: , McCall DT, Saudia A, Hamma RF, Reusch JE, Barto P: Are low-icome elderly patiets at risk for poor diabetes care? Diabetes Care 27: , Gu K, Cowie CC, Harris MJ: i adults with ad without diabetes i a atioal cohort of the U.S. populatio, Diabetes Care 21: , Arday SL, Arday DR, Moroe S. Zhag J: HCFA s racial ad ethic data: curret accuracy ad recet improvemets. Health Care Fiac Rev 21: , Flemig C, Fisher ES, Chag CH, Bubolz TA, Maleka DJ: Studyig outcomes ad hospital utilizatio i the elderly: the advatages of a merged data base for Medicare ad Veteras Affairs hospitals. Med Care 30: , Wright SM, Daley J, Peterso ED, Thibault GE: Outcomes of acute myocardial ifarctio i the Departmet of Veteras Affairs: does regioalizatio work? Med Care 35: , She Y, Hedricks A, Zhag S, Kasis LE: VA erollees health care coverage ad use of care. Med Care Res Rev 60: , Reiber GE, Koepsell TD, Mayard C, Hass LB, Boyko EJ: Diabetes i oveteras, veteras, ad veteras receivig Departmet of Veteras Affairs health care. Diabetes Care 27 (Suppl. 2):B3 B9, DIABETES CARE, VOLUME 27, NUMBER 10, OCTOBER 2004