Hospitalization and Mortality Rates for Peptic U h ~ ea r Comparison s : of a Large Health Maintenance Organization and United States Data

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1 GASTROETEROLOGY 1982;83:18-16 Hspitalizatin and Mrtality Rates fr Peptic U h ea r Cmparisn s : f a Large Health Maintenance Organizatin and United States Data JOH H. KURA TA, GORDO D. HODA, and HAROLD FRAKL Center fr Ulcer Research and Educatin, Veterans Administratin Wadswrth Medical Center; UCLA Schl f Medicine and Public Health, Ls Angeles, Cali'frnia; Suthern Califrnia Kaiser Permanente Medical Grup; and Kaiser Fundatin Hspitals, Suthern Califrnia Hspital discharge and mrtality rates fr peptic ulcer disease frm fr a large Health Maintenance Organizatin, the Kaiser-Permanente Medical Care Prgram f Suthern Califrnia, are cmpared with the crrespnding rates fr the United States. The Kaiser-Permanente Medical Care Prgram hspitalizatin and mrtality age-adjusted rates fr ulcers are well belw the natinal rates. In cmparisn with the 25%-31% decline in the natinal ulcfjr hspitalizatin rate, the Kaiser-Permanente Medical Care Prgram rate has been relatively stable. Mst f the decline in natinal ulcer hspitalizatins is due t a decrease in hspitalizatins fr uncmplicated cases. The Kaiser-Permanente Medical Care Prgram uncmplicated hspitalizatin rates are <25% f the natinal rate after age-adjustment and have been relatively stable ver time. The age-adjusted Kaiser-Permanente Medical Care Prgram rates fr ulcers with hemrrhages and perfratins are 77% f the natinal data. These data Received February 17, Accepted June 4,1982. Address requests fr reprints t: Jhn Kurata, PhD., Veterans Administratin Wadswrth Center, Building 115, Rm 215, 691/ 151 G CURE, Ls Angeles, Califrnia 973. This wrk was supprted by atinal Institute f Arthritis, Metablism, and Digestive Diseqses, Grant #AM17328, Medical Research Service f the Veterans Administratin and Center fr Ulcer Research and Educatin. Sme f the basic data used in this study were supplied by the Cmmissin n Prfessinal and Hspital Activities, Ann Arbr, Michigan. In these data the identities f individual hspitals were nt revealed in any way. Any analysis, interpretatin, r cnclusins based n these data is slely that f the authrs and the Cmmissin n Prfessinal and Hspital Activities specifically disclaims respnsibility. The authrs thank Dr. Janet Elashff, Dr. Jerry Rtter, and Ms. Belinda Haile fr their helpful cmments and criticism f this manuscript. They als thank Ms. Bnnie Klein, Ms. Suzanne Wd, and Ms. Willberta Swann fr their assistance with the data by the American Gastrenterlgical Assciatin /82/1118-9$2.5 suggest that part f the decline in natinal hspitalizatin rates fr peptic ulcer disease may be due t changes in medical management (lnd hspitalizatin criteria. In additin, this study supprts the results f ther studies which shw that hspitalizatin rates are lwer in Health Maintenance Organizatins than in nn-health Maintenance Organizatins with n apparent adverse impact n utcme. It has been estimated that abut 5%-1% f the persns in the United States can expect t develp ulcers during their lifetime (1-3). In 1977, the cst f this disease in the United States was apprximately billin dllars annually (4-6). Recently, several investigatrs have reprted dramatic declines in the hspitalizatin and mrtality rates fr peptic ulcer disease (7-11). Pssible causes fr these declines include changes in ulcer incidence (the number f new cases per year), severity f the disease, diagnstic r cding practices, effectiveness f treatment, medical management, and criteria fr hspitalizatin (12). Identificatin f the imprtance f each f these factrs culd increase ur understanding f peptic ulcer disease and pint the directin fr further study. This paper presents hspitalizatin and mrtality data fr the 1.5 millin members f the Kaiser Permanente Medical Care Prgram (KPMCP) in the Suthern Califrnia Regin, and cmpares them with natinal trends. This apprach allws cmparisns f hspitalizatin and mrtality data frm a Health Maintenance Organizatin (HMO), which has a well-defined ppulatin using ne type f health care delivery system, with the natinal data which are based primarily n nn-hmo types f medical care. [Fr the purpses f this paper, an HMO is defined as an rganizatin that "assumes a cntractual respnsibility t prvide r assure the rlelivery

2 vember 1982 PEPTIC ULCER TREDS I THE U.S. AD A HMO 19 f health services t a vluntarily enrlled ppulatin that pays a fixed premium that is the HMO's majr surce f revenue" (13).] The results prvide evidence that peptic ulcer incidence may nt be decreasing as much as previusly speculated (9,1) and at the same time presents sme new evidence cncerning the efficiency f HMO vs. nn-hmo medical care prviders. Ppulatin and Methds Suthern Califrnia Kaiser-Permanente Medical Care Prgram The Suthern Califrnia Regin f the KPMCP includes eight medical centers and satellite clinics in Ls Angeles, Orange, San Bernardin, and San Dieg Cunties. The membership has grwn steadily frm.8 millin in 197 t abut 1.5 millin in 198. The ppulatin figures used fr this paper were based n the furth-quarter enrllment fr all KPMCP members fr the years Age breakdwns were available fr the years The general age distributin f the KPMCP ppulatin has nt changed significantly between 1974 and 198. It is a yunger ppulatin than the United States ppulatin. Members age 65 yr r lder cmprise rughly 5% f the KPMCP membership, whereas fr the United States ppulatin they cmprise between 9% and 11%. Fr each 5-yr age categry under the age f 6, the prprtin f men t wmen in the KPMCP is similar t the United States ppulatin. Hwever, in the ppulatin ver age 6, there are mre wmen than men in the United States while there are mre men than wmen in the KPMCP. (Table 1). Hspital Discharge fr Kaiser-Permanente Medical Care Prgram The number f hspital discharges with a primary diagnsis f peptic ulcer disease was btained frm the yearly cmputer summary f all KPMCP hspital discharges frm Because f prblems with the cmputer recrd keeping system, data fr 1979 were nt available fr analysis. Diagnses f peptic ulcer were based n the Internatinal Classificatin f Diseases, Adapted (ICDA) Between 197 and 198 the Suthern Califrnia Regin f the Kaiser Permanente Medical Care Prgram used three different versins f ICDAs t classify the hspital discharges. The ICDA-8 (14) was used between 197 and 1974, the H-ICDA c 2 (15) was used between 1975 and 1978, and the ICD-9-CM (16) was used fr The first three digits f the ICDA cde fr peptic ulcer disease did nt change between these adaptatins and revisin changes. Hwever, the furth digit cde used t classify uncmplicated cases, hemrrhages, and perfratins did change substantially between them. All patients wh were hspitalized fr cmbined hemrrhage and perfratin are included under perfratin in this paper. (See Table 2.) It shuld be emphasized that hspital discharges and nt persns hspitalized are being examined in this paper. Table 1. Sex Distributin by Five-Year Age Intervals fr the United States Ppulatin and Kaiser- Permanente Medical Care Prgram fr 1975 Kaiser-Permanente Medi- Age United States ppulatin cal Care Prgram (yr) (%) Males (%) Females (%) Males (%) Females < It is pssible fr a persn t be hspitalized mre than nce in any given year. It was nt feasible t eliminate duplicate cunts since this wuld have required identifying each hspitalizatin by individual identificatin numbers fr bth the natinal and KPMCP data. Hspital mrtality data were determined frm the yearly cmputer summary f hspital discharges using the primary diagnsis based n the ICDA cdes and a discharge status f death. This is synnymus with the primary cause f death listed n the death certificate. It is pssible fr a persn t die frm peptic ulcer disease withut being hspitalized r t die in a nn-kaiser hspital. Hwever, Elashff and Grssman (8) reprt that hspital mrtality data frm the Cmmissin n Prfessinal and Hspital Activities and the death certificate data frm the United States Vital Statistics Office differed by nly 5%-15% fr the years This suggests that mst peptic ulcer deaths d ccur in a hspital. It is unlikely that many KPMCP members have died frm peptic ulcers in a nn-kpmcp hspital since there are few requests frm members fr payments t "ut f area" nn KPMCP hspitals. Mst f these requests are fr accident and heart failure patients. Hspital discharge rates were calculated by taking the number f discharges divided by the KPMCP membership fr the crrespnding year. United States Data In this paper, data n hspital discharges fr the United States are based n reprts frm the Cmmissin n Prfessinal and Hspital Activities (CPHA) and the atinal Center fr Health Statistics (CHS). Briefly, the CPHA data prvide estimates fr all nnfederal shrt-stay hspital discharges in the United States based n a sample f reprting hspitals. The methds have been described elsewhere (8). These estimates were cnverted t rates by

3 11 KURATA ET AL. GASTROETEROLOGY Vl. 83,. 5 Table 2. Internatinal Classificatin f Disease, Adapted (ICDA) Fur-Digit Cdes Used t Classify Uncmplicated, Hemrrhage, and Perfratin fr the Kaiser-Permanente Medical Care Prgram Data ICOA revisin Uncmplicated Hemrrhage Perfratin ICOA-8 xxx.9 xxx. xxx.l,xxx.2 H-ICO-2 xxx.o xxx. 1 xxx.2,xxx.3 ICO-9-CM xxx.3,xxx.7,xxx.9 xxx.o,xxx.4 xxx. 1,xxx.2,xxx.5, xxx.6 "xxx" refers t , the first three digits f the ICDA Cde. using estimates f the United States ppulatin btained frm United States census materials (17,18). The CHS reprted hspital discharge rates fr peptic ulcer disease in the Hspital Discharge Survey are based n a sample f ver 4 nnfederal shrt-stay hspitals (19). The methds have been described elsewhere (2). United States mrtality rates fr peptic ulcer disease were btained frm the United States Vital Statistics Office publicatins fr (21,22). These figures are based n a cmplete enumeratin f all death certificates except fr 1972 which is based n a 5% sample and 1979 and 198 which are based n a 1% sample. Cmmissin n Prfessinal and Hspital Activities data als prvide an estimate f United States hspitalizatin mrtality rates fr peptic ulcer disease by using a primary diagnsis f peptic ulcer disease and a discharge status f death. Bth CPHA and KPMCP hspitalizatin mrtality are based n the primary diagnsis fr hspitalizatin; whereas the United States Vital Statistics data are based n the "underlying cause f death." Hwever, the CPHA and the United States Vital Statistics data differed by nly 5%-15% between 197 and 1978 (8) which suggests that these data are cmparable. Results The results are presented in five subsectins. In the first tw, the hspitalizatin and mrtality data fr the verall categry f peptic ulcer disease (aggregated ICDA cdes ) are examined. In the third subsectin, the hspitalizatin data are presented separately by type f peptic ulcer, stmach r dudenal, and analyzed in further detail. In the next level f analysis, the hspitalizatin rates fr stmach and dudenal ulcers are further examined by the fur-digit subcdes fr uncmplicated, hemrrhage, and perfratin cases. In the last subsectin, hspitalizatin trends fr ther digestive diseases are cmpared with the peptic ulcer data. Hspitalizatins Cmmissin n Prfessinal and Hspital Activities data fr the United States shw that hspitalizatin rates fr peptic ulcer disease (ICDA cdes ) declined by 31% frm 227 per 1, in 197 t 157 per 1, in atinal Center fr Health Statistics data are similar (Figure 1). Rates fr the KPMCP ppulatin have been relatively stable but much iwer than fr the United States as a whle. The indirect methd f age-adjustment (23) was used t calculate standardized mrbidity ratis * (SMR). Age-specific hspitalizatin rates frm the CPHA were used as the standard. After age-adjustment, peptic ulcer hspitalizatins at KPMCP were abut ne-third f the natinal rate (Table 3). Mrtality The United States mrtality rate fr peptic ulcer disease has als shwn a decline (41%) frm 4.2 per 1, in 197 t 2.5 per 1, in Cmmissin n Prfessinal and Hspital Activities hspital mrtality rates are similar (Figure 2). The KPMCP hspital mrtality rate is much lwer than the natinal rate and des nt shw any nticeable time trend, pssibly due t the small number f * Standardized mrbidity rati = bserved cases/expected cases ffi :::i 8 a::: en 6 :J: 4 2 "'....."," tinal (CHS)... / KPMCP '_i._ _ Figure 1. Hspitalizatin discharge rates fr peptic ulcer disease (ICOA: ) fr the United States and Kaiser-Permanente Medical Care Prgram frm 197 t 198. Rates are reprted per 1, ppulatin. Based n data frm Cmmissin n Prfessinal and Hspital Activities and atinal Center fr Health Statistics (19).

4 vember 1982 PEPTIC ULCER TREDS I THE U.S. AD A HMO 111 Table 3. Age Standardized Mrbidity Ratis fr Peptic Ulcer Disease Hspitalizatins (ICDA Cdes ) fr the Suthern Califrnia Kaiser Permanente Medical Care Prgram, umber f hspitalizatins fr ICDA Standardized cdes at mrbidity Year Suthern Califrnia Kaiser-Permanente ratis a a The number f bserved hspitalizatins divided by the expected number f hspitalizatins based n the age-specific hspitalizatin rates frm the Cmmissin n Prfessinal and Hspital Activities. peptic ulcer deaths. Using the age-specific United States mrtality rates, the KPMCP hspital mrtality rates were age-adjusted fr The SMR ranged frm.23 in 1974 t.53 in 1977 (Table 4). Hspitalizatins by Type f Ulcer-Stmach and Dudenal Hspitalizatin rates brken dwn by stmach and dudenal ulcers are presented in Figure 3. The general decline in the natinal peptic ulcer 4 atinal (CPHA) Table 4. Age Standardized Mrtality Ratis fr Peptic Ulcer Disease Deaths (ICDA Cdes ) fr the Suthern Califrnia Kaiser-Permanente Medical Care Prgram, umber f hspital deaths with a primary diagnsis Standardized f peptic ulcer disease mrtality Year (ICDA cdes ) ratis a a umber f bserved hspital deaths divided by the expected number f deaths fr peptic ulcer disease (ICDA Cdes ) frm the age-specific mrtality rates reprted by the U.S. Office f Vital Statistics (21). hspitalizatin rates frm 197 t 1978 is largely due t the decline in dudenal ulcer hspitalizatins. The dudenal ulcer hspitalizatin rate fr the United States data exhibited a 46% decline, frm 153 t 82 per 1,. The crrespnding Kaiser hspitalizatin rate declined nly 19%, frm 32 t 26 per 1, (Table 5). The Spearman's rank crrelatin analysis (24) suggests that this decline, thugh small, is statistically significant (r = -.81, P <.1). After indirect age-adjustment, dudenal hspitalizatin rates fr KPMCP range frm.3 t.37 f thse fr the United States. The United States hspitalizatin rate fr ulcer f the stmach shwed a 25% decline between 197 (57 per 1,) and 1978 (48 per 1,) (Figure 3). Based n the number f hspitalizatins (nt rates), Elashff and Grssman (8) did nt find this decline 3 a:: UJ a... en 2 :I: ti UJ U.S. Vital Statistics KPMCP / - - A, / \ /...- /' \ /.5 / '..-...! q, 14 a: 12 1 en z 8 :J 6 <I: t- a::: 4 en J: tinal (CPHA)' Dudenal Ulcer tinal (CPHA)' Gastric Ulcer Figure 2. Peptic ulcer disease (ICDA Cde ) mrtality rates fr the United States and Kaiser-Permanente Medical Care Prgram frm 197 t 198. Rates are reprted per 1, ppulatin. Based n data frm Cmmissin n Prfessinal and Hspital Activities and U.S. Vital Statistics Office (21,22). Figure 3. Hspitalizatin discharge rates fr ulcer f the stmach (ICDA Cde 531) and ulcer f the dudenum (ICDA Cde 532) fr the United States and Kaiser-Permanente Medical Care Prgram frm 197 t 198. Rates are reprted per 1, ppulatin. Based n Cmmissin n Prfessinal and Hspital Activities data.

5 112 KURAT A ET AL. GASTROETEROLOGY Vl. 83,. 5 Table 5. Hspitalizatin Rates (Per 1, Enrlled Members) fr Dudenal Ulcer (ICDA Cde 532) fr the Suthern Califrnia Kaiser-Permanente Medical Care Prgram, , 198 Uncmpli- Hemrcated rhage Perfratin Ttal Year. Rate. Rate. Rate. Rate R P <.2 > Spearman's rank crrelatin. t be statistically significant. The crrespnding KPMCP rates fr ulcer f the stmach were cnsiderably lwer than the natinal rates, ranging frm 14 t 2 per 1, between 197 and 198 (Table 6). The change was nt statistically significant with Spearman's rank crrelatin tests. After age-adjustment t the CPHA data, the SMR ranged frm.4 t.45 fr 1974 t Hspitalizatin by Fur-Digit Subcde Uncmplicated, Hemrrhage, and Perfratin The KPMCP stmach and dudenal ulcer hspitalizatin rates were further analyzed by the ICD Table 6. Hspitalizatin Rates (Per 1, Enrlled Members) fr Gastric Ulcer (ICDA Cde 531) fr the Suthern Califrnia Kaiser-Permanente Medical Care Prgram, , 198 Uncmpli- Hemrcated rhage Perfratin Ttal Year. Rate. Rate. Rate. Rate R P.6-.1 <.2 >.2 >.2 Spearman's rank crrelatin. 4 3 It:: ""' a.. C/) 2 ::::i a::: 1 :I: -- tinal (CPHA) ---- KPMCP U n c i c a l e d Figure 4. Hspitalizatin discharge rates fr gastric ulcer (ICDA Cde 531) fr the United States and Kaiser-Permanente Medical Care Prgram frm 197 t 198 by uncmplicated cases, hemrrhage, r perfratin. Rates are reprted per 1, ppulatin. Based n Cmmissin n Prfessinal and Hspital Activities data. subcdes fr uncmplicated cases, hemrrhage, and perfratins. Data in Figures 4 and 5 shw that the majr reasn that the KPMCP rates are lwer than the natinal rates is because f a much lwer hspi- 1 g. 8 It:: ""' a.. C/) Z 6 ::::i 4 a:: C/) :I: 2 Hemrrhage '\.- -- atinal (CPHA) ---- KPMCP cr-..---{)'" _ "" / '... / '... L Uncmplicated Perfratin... -e_ Figure 5. Hspitalizatin discharge rates fr dudenal ulcer (ICDA Cde 532) fr the United States and Kaiser Permanente Medical Care Prgram frm 197 t 198 by uncmplicated cases, hemrrhage, r perfratin. Rates are reprted per 1, ppulatin. Based n Cmmissin n Prfessinal and Hspital Activities data.

6 vember 1982 PEPTIC ULCER TREDS I THE U.S. AD A HMO 113 talizatin rate fr uncmplicated cases fr bth ulcers f the stmach and dudenum. These data als illustrate that the small decrease that ccurs fr the KPMCP dudenal ulcer hspitalizatins are primarily due t the decline in uncmplicated cases. The average SMR ( ) fr uncmplicated cases f stmach ulcers was.25, as cmpared with.85 fr hemrrhages and perfratins cmbined. Fr dudenal ulcer hspitalizatins, the average SMR was.13 fr uncmplicated cases, and.77 fr cases with cmplicatins (hemrrhages and perfratins). The average SMR fr the natinal and KPMCP hspitalizatin rates fr peptic ulcer cmplicatins suggests that the KPMCP ppulatin might be at slightly "lwer risk" f develping peptic ulcer disease than the natinal ppulatin. Hwever, since the average SMR fr cmplicated cases is five times higher than that fr uncmplicated cases, the large difference in ulcer hspitalizatin rates fr these tw ppulatins is prbably nt due t just this small amunt f "lwer risk." Cmplicatins are ften thught t be useful indicatrs f "risk" n the assumptins that the rate f cmplicatins per ulcer case remains cnstant and that cmplicatins are less likely t escape detectin and hspitalizatin (1,25). Hwever, it shuld be nted that the same bias that leads t higher hspitalizatin rates fr uncmplicated ulcers may als affect the decisin t hspitalize r nt hspitalize patients with minr degrees f cmplicatins. The KPMCP hspitalizatin rates fr dudenal ulcer perfratins (Table 5) shw sme, but nt a significant, decrease thrugh the perid f this study. Hwever, there are large fluctuatins in these rates due t the small number f cases. The United States data d nt shw a significant decrease (8) fr dudenal ulcer perfratins. Hspitalizatins fr Other Digestive Diseases Because the apparent decrease in hspitalizatin rates fr stmach and dudenal ulcers may be partially due t a change in diagnstic practices which wuld be reflected by an increase in rates fr ther categries, the KPMCP hspitalizatin rates fr ulcer-site unspecified, gastrjejunal ulcer, and gastritis/dudenitis, alng with stmach and dudenal ulcers were graphed in Figure 6. Bth ulcer-site unspecified and gastrjejunal ulcer shw relatively lw and stable hspitalizatin rates ver time. Gastritis/dudenitis has shwn a large increase ver time. When the hspitalizatin rates fr ulcer disease and gastritis/dudenitis are cmbined, there is an increase in the hspitalizatin rates fr this cmbined categry between 197 and 198. A similar analysis f natinal CHS data is 8 8 a:: 6 (f) Z!;i 4 :J 2 :I: I O O, Dudenal Ulcer (532) Gastric Ulcer (531) := /r / < ' - G a s l r i l (535) i S / D u d e n i S.',--.../ Ulcer, sile unspecified (533) e YEAR Figure 6. Hspitalizatin discharge rates fr ICDA Cdes fr Kaiser-Permanente Medical Care Prgram frm 197 t 198. Rates are reprted per 1, ppulatin. graphed in Figure 7. These data als shw a decrease in hspitalizatin fr dudenal ulcers and an increase fr gastritis/dudenitis. Hwever, these rates are much higher than the crrespnding rates fr the KPMCP ppulatin. In additin, the natinal data shw a mre dramatic decrease in hspitalizatins fr dudenal ulcers and a much smaller increase fr gastritis/dudenitis. Hspitalizatin rates fr ulcer disease declined 25% between 197 and 198. When hspitalizatin rates fr ulcer disease and gastritis/ dudenitis are cmbined, the percentage decrease between 197 and 198 is reduced t 12%, Hwever, this cmbined categry still shws a statistically significant decrease ver time (r=-.84, p <.5) and can accunt fr nly part f the decline in ulcer rates. It may be pssible that sme f the decline in the dudenal ulcer hspitalizatins may be due t a change in diagnstic practices (Le., increase in endscpies) resulting in mre cases that were previusly assumed t be peptic ulcers nw being classified as gastritis/dudenitis. Of curse, the increase in gastritis/dudenitis hspitalizatins may als indicate a real change in the frequency f this disease. Discussin This study has prduced findings in tw majr areas: (a) Differences in HMO vs. nn-hmo prviders and (b) time trends in peptic ulcer disease. During the 197s the age-adjusted peptic ulcer hspitalizatin rate at KPMCP was apprximately 4% f the natinal rate (Table 3). This lwer rate is

7 114 KURATA ET AL. GASTROETEROLOGY Vl. 83, f5 1 a. 8 6 ::i e; t astritis/dudenitis (535),- -fi""......",,"""... _... Dudenal Ulcer (532)/,1 --- G a s t r i(531l"\.. c c e r. --- I c site e r unspecified, (533) G a s t r a -(534) j e j u n a l YEAR Figure 7. Hspitalizatin discharge rates fr ICDA Cdes fr the United States based n atinal Center fr Health Statistics data frm 197 t Rates are reprted per 1, ppulatin. cnsistent with results frm ther studies which shw that hspitalizatin fr "all causes" is 4%- 5% lwer fr the Oregn, rthern Califrnia, and Suthern Califrnia Regins f the KPMCP than nn KPMCP enrllees (26). The data were nt adjusted fr differences in the sex distributin between the tw ppulatins. If the KPMCP rates had been sexand age-adjusted, this wuld have further increased the differences in the rates, since there is a greater prprtin f lder men in the KPMCP ppulatin than in the United States ppulatin. Thus the lwer KPMCP hspitalizatin rates fr peptic ulcer are nt due t differences in the sex distributin. It is imprtant t nte that even thugh the age and sex distributin fr these tw ppulatins have been taken int cnsideratin, the risk f peptic ulcers amng the KPMCP ppulatin may still nt be representative f the United States ppulatin. There is gd evidence that the lwer ulcer hspitalizatin rates fr the Suthern Califrnia KPMCP are nt just a reflectin f lwer rates fr this particular gegraphic regin. brega et al. recently reprted that in 1976 the verall hspital discharge rate, adjusted fr age and sex, was 3% less than the natinal rates in tw Minnesta medical grup practices: the May Clinic and the Olmsted Medical and Surgical Grup (27). They cncluded that the rganizatin f medical care may have an imprtant influence n hspital utilizatin. Of especial relevance was their finding that hspitalizatin fr peptic ulcer disease in these medical grups was nly 39% f the natinal rate. This is very similar t KPMCP's ulcer hspitalizatin rate which is 4% f the natinal rate. Other evidence cmes frm a Califrnia Hspi- tal Facilities Cmmissin Reprt n hspital utilizatin in the KPMCP and nn-kpmcp systems. This reprt shws that frm , verall hspital admissin rates fr KPMCP members ranged between 51% and 58% f the admissins rate fr the nn-kpmcp ppulatin in Suthern Califrnia (28). Luft (13,26) prpses fur pssible reasns fr the lwer hspital admissins in HMOs. In the fllwing discussin, each f these reasns is evaluated with respect t the data frm this study. "Discretinary" (unnecessary) case admissins are reduced in an HMO. It is interesting that at the natinal level the great majrity f hspitalizatins fr peptic ulcers are fr "uncmplicated" cases and mst f the drp in peptic ulcer hspitalizatin rates ver the last decade are due t a decrease in these "uncmplicated" cases (Figures 4 and 5). In the KPMCP, peptic ulcer hspitalizatin rates have nt shwn a significant decrease and hspitalizatins fr "uncmplicated" cases represent nly a third f the ttal peptic ulcer hspitalizatins. Hspitalizatins fr "uncmplicated" peptic ulcer cases in nn KPMCP hspitals are appraching the rate at KPMCP hspitals. If "uncmplicated" cases can be equated with "discretinary" cases, this evidence supprts Luft's thery that HMOs identify and screen ut cases that really d nt require hspitalizatin. Thus, mst f the decrease in the natinal hspitalizatin rates fr peptic ulcer might be due t a change in the standards f hspitalizatin twards the nes used in HMOs. The secnd pssibility is that self-selectin amng HMO enrllees may result in a healthier ppulatin r greater aversin t hspital admissins amng HMO enrllees. This pint cannt be directly addressed with the data frm this study. Hwever, since the cmbined categry f hemrrhage and perfratin rates (which may be better indicatrs f peptic ulcer disease) in the KPMCP ppulatin are clse t the natinal rates, the KPMCP ppulatin is prbably nt at a markedly lwer risk f develping this disease than the nn-kpmcp ppulatin. In additin, a recent paper by Blumberg (29) indicates that the KPMCP ppulatin in Califrnia is nt "healthier" than ther health insurance enrllees based n activity limitatins due t chrnic cnditins and self-appraised health status. Anther factr which might be related t the bserved differences in hspital admissins is that nn-hmo patients may be mre recalcitrant t recmmended therapy due t lack f cmpliance in certain ppulatin subgrups based n sciecnmic factrs, and s n. If this is true, this might result in higher admissin rates fr uncmplicated cases natinally than fr KPMCP. A third pssibility is that HMOs prvide preven-

8 vember 1982 PEPTIC ULCER TREDS I THE U.S. AD A HMO 115 tive care which reduces the health prblems that wuld require hspital admissins. This paper des nt prvide any evidence fr r against this pssibility. Hwever, data frm the Califrnia Hspital Facilities Cmmissin (28) shw that the rate fr utpatient visits has been much higher fr KPMCP than nn-kpmcp enrllees. Thus, the larger number f utpatient visits might be substituting fr hspital admissins r they might be reducing the need fr hspital admissins by prviding preventive measures. The furth pssibility is that HMOs undertreat, r nn-hmos vertreat their patients. Althugh it is pssible that Kaiser arbitrarily reduces hspitalizatin by screening ut even thse wh need hspitalizatin, the mrtality data d nt supprt this explanatin. The age-adjusted peptic ulcer mrtality rates are apprximately 4%-5% lwer than the natinal rate (Table 4). This is cnsistent with the results f ther studies which shw that the Kaiser mrtality rate fr all causes is lwer than fr nn-kaiser ppulatin and that utcmes in HMOs are the same as r smewhat better than thse in cnventinal practice (26). Except fr the evidence presented in the first item (discretinary hspitalizatins), this study des nt address the issue f "vertreatment." In regard t peptic ulcer time trends, the KPMCP hspitalizatin rates shw nly minr changes ver time, except fr a 19% reductin in dudenal ulcer discharges. Hwever, this decline in dudenal ulcer discharges is small cmpared with the decline in the natinal rates. Mst f the decline in the natinal peptic ulcer hspitalizatin rate is due t the decrease in "uncmplicated" cases. This may be due t changes in the medical management and hspitalizatin criteria fr peptic ulcers. It has been nted that few patients are being hspitalized fr bed rest and "milk diet" (3). This change wuld mst likely affect the less seriusly ill r uncmplicated cases resulting in fewer hspitalizatins fr these patients. It shuld be emphasized that these results d nt eliminate the pssibility that the ther ptential factrs such as decreased incidence, decreased severity f disease, mre successful treatment, and change in diagnstic practices are imprtant. With the exceptin f incidence studies, evidence n these pssibilities has nt been previusly reprted. The results f studies using "indirect" r arbitrarily defined measures f incidence are equivcal. Vgt and Jhnsn (1), using data frm an HMO with 22, members, shwed a ntable decline in utpatient episdes f dudenal ulcers frm 1967 thrugh Mendelff (9) reprted a 5% decline in the number f diagnses f dudenal ulcers amng the United States wrk frce and armed services persnnel between 196 and Hwever, the Health Interview Surveys f the atinal Center fr Health Statistics (31,32) shwed n substantial decline in "perceived" ulcer incidence between 1968 and In additin, the study f peptic ulcer incidence by Bnnevie did nt find any nticeable decrease in Denmark between 1963 and 1968 (33-35). He repeated the study during 1978 and 1979 and fund n ntable changes in incidence frm the earlier study (Bnnevie, unpublished data, 198). It is difficult t cmpare the trends in Denmark with the United States since the study cnducted in Denmark did nt reprt hspitalizatin and mrtality rates. A recent study by Cggn et al. (3) f peptic ulcers in England and Wales presents an interesting cntrast t the results f ur study. Overall hspitalizatins and mrtality rates fr peptic ulcers have fallen in bth the United States and England and Wales. Hwever, in England and Wales these rates have fallen fr perfrated as well as nnperfrated ulcers. In additin, Cggn reprts that ther studies in the United Kingdm shw that diagnsis f peptic ulcer by cnsultants had decreased, and "the amunt f certified incapacity fr wrk ascribed t peptic ulcer has als fallen" (3). Data frm ther cuntries such as these have been used t reinfrce the belief that ulcer disease has been decreasing in the United States. Hwever, these cmparisns are smewhat limited since there are many imprtant differences in the epidemilgy f ulcer disease between the United States and the United Kingdm. Fr example, in England and Wales gastric ulcer admissin rates fell as much as the rates fr dudenal ulcers, whereas the gastric ulcer rates in the United States have remained relatively stable. Als, the perfratin rates fr ulcer disease in England and Wales are apprximately duble that fr the United States. Summary and Cnclusins This study shws that the KPMCP members have a much lwer hspitalizatin and mrtality rate fr peptic ulcer disease than the United States ppulatin. In additin, hspitalizatins fr uncmplicated dudenal and gastric ulcers have remained stable fr the KPMCP ppulatin while there has been a significant drp in these rates fr the United States ppulatin. It is suggested that sme f the decrease in the natinal hspitalizatin rate fr peptic ulcer disease may be due t changes in medical management and criteria fr hspitalizatin. These results strengthen the claims made by ther investigatrs (26) that hspitalizatin rates are lwer in HMOs

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