MILITARY MEDICINE, 174, 9:936, 2009 A Four-System Comprison of Ptients With Chronic Illness: The Militry Helth System, Veterns Helth Administrtion, Medicid, nd Commercil Plns Teres B. Gibson, PhD * ; Todd A. Lee, PhrmD, PhD ; Christine S. Vogeli, PhD ; Juli Hidlgo, ScD, MSW, MPH ; Ginger Smith Crls, MA ; Ktherine Sredl, BA ; Susn DesHrnis, PhD ; Willim D. Mrder, PhD ** ; Kevin B. Weiss, MD, MPH ; Thoms V. Willims, PhD ; Alexndr E. Shields, PhD ABSTRACT We compred chronic cre utiliztion in four mjor helth systems in the U.S.: the militry helth system (TRICARE), the Deprtment of Veterns Affirs (VA), Medicid, nd employer-sponsored commercil plns. Prevlence rtes nd key performnce indictors were constructed from dministrtive dt in federl fiscl yer 2003 for eight chronic conditions: hypertension, mjor depression, dibetes, tobcco dependence, ischemic hert disese, severe mentl illness, persistent sthm, nd stroke. Continuously enrolled beneficiries under 65 yers old were studied: TRICARE ( N = 2,963,987), VA ( N = 2,114,739), Medicid enrollees in five sttes ( N = 5,554,974), nd commercil insurnce ( N = 5,212,833). Condition-specific djusted prevlence rtes nd mesures were compred using the stndrdized rte rtio. For the mjority of the conditions, the estimted prevlence rtes were highest in the VA nd Medicid popultions. Prevlence rtes were generlly lower in TRICARE nd commercil plns. Medicid beneficiries hd the highest hospitliztion rtes in four of the six conditions where hospitliztion rtes were mesured. These results provide empiricl evidence of differences in chroniclly ill ptient popultions in severl of the mjor U.S. helth insurnce systems. INTRODUCTION Incresingly, chronic illness hs become mjor focus of qulity mngement ctivities. Over one hlf of nonelderly dults in the U.S. report hving t lest one mjor chronic condition. 1 Chroniclly ill individuls ccount for bout three-qurters of ll helth cre spending nd interfce with the helth cre system more thn ny other group. 2 As result, chroniclly ill popultions provide unique nd efficient focl point for qulity improvement efforts. In fct, of the 20 priority res identified by the Institute of Medicine to trnsform helth cre qulity, most re chronic illnesses. 3 * Thomson Reuters, 777 E. Eisenhower Prkwy, Ann Arbor, MI 48108. Edwrd Hines, Jr. VA Hospitl, 5th nd Roosevelt Rod, Hines, IL 60141. Msschusetts Generl Hospitl, 50 Stniford Street, 9th floor, Suite 901, Boston, MA 02114. George Wshington University School of Public Helth nd Helth Services, 2021 K Street, NW, Suite 800, Wshington, DC 20006. Thomson Reuters, 5425 Hollister Avenue, Snt Brbr, CA 93111-2348. Thoms Jefferson University School of Popultion Helth, 1015 Wlnut Street, Curtis Bldg. Suite 115, Phildelphi, PA 19107. ** Thomson Reuters, 150 Cmbridge Prk Drive, Cmbridge, MA 02140. Deprtment of Defense, 5111 Leesburg Pike, Suite 810, Flls Church, VA 22041-3206. Summry results from this study were presented t the 2007 Acdemy Helth Annul Reserch Meeting in Orlndo, FL on June 3, 2007. The opinions or ssertions herein re those of the uthors nd do not reflect the policy or position of the U.S. Deprtment of Defense or the U.S. Government. This mnuscript ws received for review in October 2008. The revised mnuscript ws ccepted for publiction in My 2009. The bility to compre the helth cre experiences of chroniclly ill popultions served by severl mjor insurnce systems, such s the militry helth system (MHS), the Deprtment of Veterns Affirs (VA), Medicid, nd employer-sponsored commercil insurnce, lends insight into the unique role tht is plyed by ech insurnce system cross the frgmented U.S. helth cre system. Comprisons mong these popultions enble risk mngement, resource mngement, performnce mngement, nd provide ssessments of the generliztion of future studies. This study stems from the MHS interest in benchmrking their ctivities ginst other systems nd ddresses criticl informtion gp by providing, to our knowledge, the first comprtive dt on prevlence nd utiliztion mesures for vriety of common chronic conditions cross these pyers nd ptient popultions. There hve been few systemtic comprisons of prevlence rtes nd utiliztion cross these helth cre systems. Previous helth cre system comprisons hve generlly focused on two helth cre systems, such s the VA to Medicre or compring the Ntionl Helth Service in the United Kingdom (U.K.) to the Kiser Permnente system in the U.S. or the comprisons hve been on reltively smll smples of the popultion. 4 8 One of the studies tht compred cre using the dtbses in this study ws n nlysis of schizophreni tretments between the VA nd employer-sponsored commercil insurnce. Leslie nd Rosenheck 7 report mixed results between the two dt sets in terms of providing cre to ptients with schizophreni, with better performnce in the commercil dt on some mesures nd better in the VA dt on other mesures. 936 MILITARY MEDICINE, Vol. 174, September 2009
METHODS Four sources of federl fiscl yer 2003 (October 1, 2002 through September 31, 2003) dt were utilized for this nlysis. For ech system, dministrtive dt including inptient dmissions, outptient clims nd encounter records, enrollment/eligibility informtion, nd prescription drug clims were nlyzed. (1) Militry Helth System (MHS). This included direct cre (militry tretment fcility) nd purchsed cre (civilin-provider) clims. (2) Commercil insurnce. The MrketScn Commercil Clims nd Encounter dtbse provided informtion on commercilly insured individuls in ll U.S. census regions with employer-sponsored helth insurnce vi lrge firms. (3) Medicid. The MrketScn Medicid dtbse included informtion from Medicid progrms in six sttes. Becuse of dt use greements, these sttes cnnot be identified. (4) Veterns Affirs. Veterns Helth Administrtion (VHA) dt were used in this nlysis. Two of the dtbses were popultion-bsed (MHS nd VA) nd two were smples (commercil nd Medicid). The ge/sex distribution of the Medicid dtbse ws reltively similr to the ntionl distribution. The commercil dtbse derived from lrge firms hd higher percentge of older dults thn the ntionl distribution of privtely insured in the Medicl Expenditure Pnel Survey (MEPS) (comprisons not shown). The MEPS counts were the best vilble for privte insurnce, lthough they contined smll nd medium-sized firms in ddition to lrge firms. 9 This study ws declred exempt (secondry dt) from review by the George Wshington University Institutionl Review Bord. Ptient Selection Beneficiries ge 5 64 yers were selected for the study. Children below 5 yers of ge were excluded, s this ws the minimum ge for the condition criteri. The elderly were lso excluded to decrese the possibility of dt nd insurnce coordintion issues with Medicre. Ptients with continuousv enrollment in federl FY 2003 were selected for inclusion. For the MHS, commercil, nd Medicid progrms continuous enrollment ws defined s enrollment throughout the yer with up to 1-month gp in coverge. MHS enrollees hd to be enrolled in TRICARE Prime, the MHS enrollment-bsed mnged cre pln. Files contining ll of the veterns enrolled in the VA were not vilble. 10 Therefore, to crete proxy for continuous enrollment, VA beneficiries with helth cre utiliztion in FY 03 nd gin in FY 04 were included in the study. This resulted in 2,963,987 MHS enrollees, 5,212,833 commercilly insured enrollees, 5,554,974 Medicid enrollees, nd 2,114,739 veterns. Condition Definitions Criteri such s disese-specific hospitliztions, emergency room (ER) visits, outptient visits, nd prescription drugs were developed to select ptients with ech of the eight conditions. Criteri for four conditions were derived from 2004 HEDIS criteri: persistent sthm, dibetes, hypertension, nd mjor depression (Tble I ).11 Criteri for the remining conditions (ischemic hert disese (IHD), severe mentl illness, stroke, nd tobcco dependence), were bsed upon combintion of disese-stging dignostic criteri 12 nd HEDIS procedure code lists for qulifying events (e.g., inptient dmission, office visit). A medicl records coder nd experts in the respective fields lso reviewed the condition criteri. Prevlence rtes report the number of ptients treted with ech condition per 1,000 continuously enrolled beneficiries in ech ge group. While the dignostic nd procedurl criteri mtch the HEDIS definition for ech of the HEDIS-bsed conditions, we deprt from HEDIS enrollment criteri to use the sme nnul denomintor for ll conditions. For exmple, HEDIS persistent sthm criteri require 2 yers of continuous enrollment. Using 1 yer of continuous enrollment, the sthm prevlence rtes herein re higher thn wht would be reported using stndrd HEDIS rtes. Mesures A brod list of ll possible performnce indictors for ech condition ws developed from sources such s the Agency for Helthcre Reserch nd Qulity, the Joint Commission on Accredittion of Helthcre Orgniztions, s well s indictors developed by the reserch tem. The finl list of indictors ws selected such tht rtes could be evluted cross conditions nd vlid comprisons could be mde cross the dt sources. Primry nd secondry indictors were selected for ll conditions except tobcco dependence. Except for ischemic hert disese nd tobcco dependence, the primry indictor selected ws the disese-specific hospitl dmission rte, which ws the number of inptient confinements per 1,000 ptients with tht condition, representing the extent of severe, cute utiliztion in ech popultion. The redmission rtes were clculted s the percentge of hospitliztions followed by redmission within 30 dys. For ischemic hert disese, the primry indictor ws the disesespecific ER visit rte since dmissions my understte the utiliztion burden becuse of high rtes of ischemic hert disese mortlity. Becuse few dministrtive clims-bsed mesures re vilble for tobcco dependence, we ssessed the extent to which ptients with tobcco dependence dignosis nd prescription for nicotine replcement therpy (NRT) were lso prescribed bupropion, n ntidepressnt pproved for smoking cesstion tht cn improve quit rtes. 13 The secondry indictor ws the 30-dy hospitl redmission rte for the sme condition. Sme-dy trnsfers were not included in the redmission rtes. MILITARY MEDICINE, Vol. 174, September 2009 937
TABLE I. Definition of Study Cohorts Condition Source of Criteri Age Rnge Dignostic Criteri Definition Persistent Asthm HEDIS 2004 5 17, 18 54, 5 54 ICD-9-CM: 493.xx (1) At lest one ER visit with sthm s the principl dignosis, or (2) At lest one cute inptient dischrge with sthm s the principl dignosis, or (3) At lest four outptient sthm visits with sthm s one of the listed dignoses nd t lest two sthm mediction-dispensing events or (4) At lest four sthm mediction dispensing events. If the ptient meets criteri 4 with leukotrine modifiers then the ptient must either: (1) Meet ny one of the other three criteri, or (2) Hve t lest one dignosis of sthm in ny setting. Dibetes HEDIS 2004 18 64 ICD-9-CM: 250.xx, 357.2, 362.0, 366.41, 648.0 DRGs: 294, 295 (1) One prescription of insulin or orl hypoglycemics/ ntihyperglycemics, or (2) At lest two fceto-fce encounters with different dtes of service in n mbultory setting or noncute inptient setting with dibetes dignosis, or (3) One fceto-fce encounter in n cute inptient setting or ER with dibetes dignosis Hypertension HEDIS 2004 46 64 ICD-9-CM: 401.xx At lest one outptient encounter with hypertension dignosis Ischemic Hert Disese (IHD) Disese Stging nd Other Dt Anlysis To the extent possible, treted prevlence nd utiliztion dt were compred with reference rtes (publicly nd nonpublicly vilble) for ech of the popultions s prt of qulity ssurnce ctivities. When comprisons were possible, the clculted rtes were similr to the references rtes. Sttisticl Anlysis Becuse of dt use greements, the dtbses were not pooled. To mke results more comprble cross ech of the 46 64 ICD-9-CM: 410.00-414.9x At lest two encounters on different dtes (n outptient encounter or n encounter in n cute inptient setting or ER) with n IHD dignosis Mjor Depression HEDIS 2004 18 64 ICD-9-CM: 296.2, 296.3, 298.0, 300.4, 309.1, 311.x DRGs: 426 (Exclude if the principl dignosis is 301.12.) Severe Mentl Illness Stroke Tobcco Dependence Disese Stging nd Other Disese Stging nd Other Disese Stging nd Other x is ny vlid digit 0 through 9. b y = 1, 2, 3, or 4. 18 64 Mjor Depression (ICD-9-CM 296.2y b,296.3y) bipolr disorder (ICD-9-CM 296.0y, 296.1y, 296.4y, 296.5y, 296.6y, 296.7, 296.80, 296.81, 296.82, 296.89) or schizophreni (ICD-9-CM 295.xy) 46 64 ICD-9-CM: 430.xx, 431.xx, 432.x, 433.x1, 434.x1, 436.xx (1) At lest one principl dignosis of mjor depression in ny setting, or (2) At lest two secondry dignoses of mjor depression on different dtes in ny outptient setting, or (3) At lest one secondry dignosis of mjor depression in ny inptient dischrge. Lb clims should not be included in the identifiction criteri. (1) At lest one principl dignosis of ny one of these conditions (mjor depression, bipolr disorder, schizophreni, or nonorgnic psychoses) in ny setting, or (2) At lest two secondry dignoses of ny one of these conditions on different dtes in ny outptient setting, or (3) At lest one secondry dignosis of ny one of these conditions in ny inptient dischrge At lest one dignosis in ny setting of stroke 18 64 ICD-9-CM: 305.1 (1) At lest one dignosis in ny setting of tobcco dependence, or (2) At lest one prescription for n utonomic nicotine preprtion popultions, rtes were stndrdized to the 2000 U.S. census. We ge/sex djusted prevlence rtes nd the indictors (e.g., hospitliztion rtes) using direct stndrdiztion methods), shown in Formuls 1 nd 2. 14 k DSR = Pi * ri, (1) i= 1 where DSR = directly stndrdized rte, P i = the proportion of the stndrd popultion in the i th cell out of totl of k cells (strt), nd r i = the crude rte for the study popultion in the i th cell. The vrince ws clculted s: 938 MILITARY MEDICINE, Vol. 174, September 2009
k 2 i i= 1 v = P * r / n, (2) where n i = the smple size for the study popultion in the i th cell. For prevlence rtes, this ws the study popultion in the cell. For hospitliztion nd emergency deprtment (ED) visit rtes, where the denomintor ws the number of ptients with the condition, n i ws the popultion in the cell with the condition. For binomil outcomes we replced r i by the product r i * (1 r i ). The results were ssessed for sttisticlly significnt differences pirwise cross insurnce systems. The stndrdized rte rtio 14 ws used to compre ll pirs of djusted rtes. SRR DSR =, (3) DSR where nd b re two systems. A 95% confidence intervl for the SRR is: where i b CI = exp(ln( SRR) ± 196. vr(ln( SRR)), (4) vr(ln( SRR)) i v vb = +, (5) DSR DSR where v nd v b were clculted using (2) nd DSR nd DSR b were clculted using (1). When compring smple nd popultion we modified this s one-smple test nd when compring two popultions we used the ctul rtes. We pplied the Bonferroni djustment to ccount for multiple comprisons. For 95% confidence level, we used Bonferroni-djusted p vlue of 0.05/6 = 0.0083 becuse there TABLE II. b re 6 pirs of comprisons between the four popultions for ech mesure. 14 Thus, insted of using z = 1.96, we used z = 2.64 to crete our 95% confidence intervls. If the 95% confidence intervl contined 1.0, we could not reject the null hypothesis of equl rtes t the 5% significnce level. All sttisticl comprisons were performed using Stt 9. RESULTS Tble II displys the undjusted ge nd gender distribution of the popultions. Consistent with expecttions, Medicid hd the highest percentge of femles (57.5%) nd the VA the lowest (11.6%). Commercil nd MHS popultions hd n lmost equl distribution of mles nd femles. The VA served the oldest popultion, the MHS popultion ws skewed towrd younger dults, the Medicid popultion ws lmost hlf children (49%), nd the commercil popultion ws lmost evenly distributed cross the ge ctegories. Persistent Asthm The overll (ge 5 54) ge/sex djusted treted prevlence rte for persistent sthm ws highest in the Medicid (22.2 per 1,000 Medicid enrollees) popultion nd lowest in the commercil popultion (10.4 per 1,000), lthough the Medicid hospitliztion rte of 58.1 per 1,000 ptients with sthm ws lmost twice the commercil hospitliztion rte ( Tble III ). Despite high peditric sthm prevlence rtes in the MHS, peditric sthm hospitliztion nd redmission rtes were the lowest. This phenomenon could reflect higher rtes of dignosis or my indicte better control within the popultion of MHS peditric ptients with sthm. Crdiovsculr Disese About one-third of VA nd MHS enrollees ge 46 64 were dignosed with hypertension; however, hospitliztion rtes Age nd Gender Distribution in FY 03, Continuously Enrolled MHS ( N = 2,963,987) VA ( N = 2,114,739) Medicid ( N = 5,554,974) Commercil ( N = 5,212,833) Gender (%) Femle 48.1 11.6 57.5 53.0 Mle 51.9 88.4 42.5 47.0 Age (%) 5 17 25.7 0.0 49.0 20.2 18 34 34.6 7.5 24.4 21.4 35 44 19.6 16.3 13.1 18.0 45 54 10.7 34.5 7.4 21.8 55 64 9.4 41.7 6.0 18.5 Adults (%) 18 34 46.5 7.5 47.8 26.8 35 44 26.4 16.3 25.8 22.6 45 54 14.5 34.5 14.6 27.4 55 64 12.7 41.7 11.8 23.2 N Adults 2,203,405 2,114,739 2,832,055 4,161,727 Continuously enrolled is defined for Militry Helth System (MHS), Medicid, nd employer-sponsored commercil systems s beneficiries in FY 03 nd llowing for 1-month gp in coverge. The VA does not hve enrollment files, therefore the VA continuously enrolled popultion is defined s documented service utiliztion both during nd post-fy 03. All comprisons between insurnce systems re significntly different, p < 0.01. Source of Dt: MrketScn Commercil nd Medicid dtbses, MHS, nd VA dministrtive dt wrehouses. MILITARY MEDICINE, Vol. 174, September 2009 939
TABLE III. Persistent Asthm (Persons Aged 5 54) nd Crdiovsculr Diseses (Persons Aged 46 64) in FY 03, Continuously Enrolled Mesures MHS VA Medicid Commercil Persistent Asthm N 60,306 65,745 103,524 53,103 Prevlence per 1,000 b 5 17 yers 27.52 N/A 17.63 14.19 18 54 yers 15.43 37.46 23.76 10.89 5 54 yers 18.59 N/A 22.16 10.40 Hospitliztions per 1,000 b 5 17 yers 38.03 N/A 65.34 47.28 18 54 yers 22.94 23.19 55.47 33.70 5 54 yers 26.88 N/A 58.05 33.34 Redmission Rte (%) b 5 17 yers 0.73 N/A 1.79 1.18 18 54 yers 2.13 13.26 6.84 4.03 5 54 yers 1.76 N/A 5.52 2.53 Crdiovsculr Diseses (46 64 yers) Hypertension N 189,876 743,974 153,851 347,567 Prevlence per 1,000 b 309.24 351.57 198.92 170.04 Hospitliztions per 1,000 b 1.12 1.53 3.04 1.56 Redmission Rte (%) b 1.24 11.52 1.70 0.94 Ischemic Hert Disese N 19,091 132,274 23,595 30,647 Prevlence per 1,000 b 30.32 47.75 31.32 14.81 Emergency Deprtment Visits per 1,000 b 332.36 177.32 307.93 438.58 Redmission Rte (%) b 3.01 20.64 5.72 5.44 Stroke N 4,904 5,294 22,140 3,607 Prevlence per 1,000 b 7.85 2.21 29.28 6.47 Hospitliztions per 1,000 b 136.23 357.04 93.00 167.52 Redmission Rte (%) b 2.64 8.61 2.35 2.70 Continuously enrolled is defined for Militry Helth System (MHS), Medicid, nd employer-sponsored commercil systems s beneficiries in FY 03 nd llowing for 1-month gp in coverge. The VA does not hve enrollment files, therefore the VA continuously enrolled popultion is defined s documented service utiliztion both during nd post-fy 03. b Age/sex djusted on the bsis of the 2000 U.S. census. Note: All comprisons between insurnce systems re significntly different, p < 0.05. Source of Dt: MrketScn Commercil nd Medicid dtbses, Militry Helth System (MHS), nd VA dministrtive dt wrehouses. were the lowest in the MHS popultion (1.1 per 1,000 MHS ptients with hypertension) ( Tble III ). While the Medicid hypertension prevlence rte ws similr to the low rte in the commercil popultion, Medicid hospitliztions (3.0 per 1,000) were the highest of the four popultions. Ischemic hert disese prevlence in the commercil popultion (14.8 per 1,000 enrollees) ws one-hlf to one-third the rte of the other popultions, lthough the ER visit rte (438.6 visits per 1,000 ptients with ischemic hert disese) ws t lest one-third higher thn the other popultions. This finding my reflect high rtes of incident ischemic hert disese within working popultion. Conversely, the VA hd the highest ischemic hert disese prevlence rte, but the lowest ER visit rte, which my correspond to fewer incident cses. The Medicid popultion hd the highest stroke prevlence rte 29.3 per 1,000 enrollees, but the lowest hospitliztion rte (93 per 1,000 stroke ptients), indicting fewer incident cses or higher rtes of ptients tht hve been disbled by stroke. In contrst, the VA hd the lowest stroke prevlence rte (2.2 per 1,000 enrollees), but the highest hospitliztion rte (357 per 1,000 stroke ptients). VA 30-dy redmissions were consistently the highest cross ech of the three crdiovsculr conditions. Mentl Disorders Mentl disorders ffect the VA nd Medicid popultions disproportiontely with rtes of severe mentl illness for the VA nd Medicid (107 per 1,000 enrollees in both popultions, p > 0.05) four times tht of the commercil nd MHS popultions ( Tble IV ). Depression rtes in the VA lso were the highest (106.5 per 1,000 enrollees) nd were 50% higher thn Medicid nd t lest twice the rtes of the commercil nd MHS popultions. Severe mentl illness hospitliztions in the VA (154.4 per 1,000 ptients with severe mentl illness) were 50% higher thn Medicid nd twice the rte of commercil nd MHS popultions. Depression hospitliztions were highest in Medicid (52.8 per 1,000 ptients with depression), but unlike severe mentl illness, depression hospitliztions were the lowest in the VA (21.1 per 1,000 ptients). 940 MILITARY MEDICINE, Vol. 174, September 2009
TABLE IV. Mentl Disorders, Dibetes, nd Tobcco Dependence in FY 03 for Persons Aged 18 64, Continuously Enrolled Mesures MHS VA Medicid Commercil Severe Mentl Illness N 55,505 216,014 270,171 106,117 Prevlence per 1,000 b 26.03 106.97 107.31 24.36 Hospitliztions per 1,000 b 88.12 154.42 95.66 70.77 Redmission Rte (%) b 6.63 22.36 19.30 9.20 Mjor Depression N 117,033 223,507 215,159 174,480 Prevlence per 1,000 b 55.07 106.54 77.35 40.70 Hospitliztions per 1,000 b 40.94 21.13 52.75 28.91 Redmission Rte (%) b 3.94 12.72 10.31 5.97 Dibetes N 88,159 348,665 229,786 234,817 Prevlence per 1,000 b 45.37 71.56 93.12 43.35 Hospitliztions per 1,000 b 32.05 30.01 46.47 21.94 Redmission Rte (%) b 4.22 13.16 10.30 4.32 Tobcco Dependence N 55,505 326,610 73,313 34,211 Prevlence per 1,000 b 39.78 105.17 26.79 7.52 Ptients Receiving NRT nd bupropion for tobcco dependence rte (%) b 63.58 14.78 29.38 31.88 Continuously enrolled is defined for Militry Helth System (MHS), Medicid, nd employer-sponsored commercil systems s beneficiries in FY 03 nd llowing for 1-month gp in coverge. The VA does not hve enrollment files, therefore the VA continuously enrolled popultion is defined s documented service utiliztion both during nd post FY 03. b Age/sex djusted on the bsis of 2000 U.S. census. Note: All comprisons between insurnce systems re significntly different, p < 0.05. Source of Dt: MrketScn Commercil nd Medicid dtbses, Militry Helth System (MHS), nd VA dministrtive dt wrehouses. Other Conditions Both Medicid nd the VA hd the highest prevlence nd redmission rtes for dibetes ( Tble IV ). While the prevlence of dibetes ws low in the MHS nd the commercil popultion (45.3 nd 43.4 per 1,000 enrollees, respectively), dibetes hospitliztions in the MHS (32.1 per 1,000 ptients with dibetes) were 50% higher thn the commercil popultion nd exceed hospitliztion rtes in the VA. Rtes of recorded dignosis of tobcco dependence vry considerbly (7.5 per 1,000 in commercil to 105.2 in the VA) nd ll were significntly lower thn the 2003 dult U.S. smoking rte of 21.5%. 15 These rtes my be correlted with ctul rtes of tobcco dependence, but my lso be relted to under-reporting of tobcco dependence in medicl clims nd medicl records. Benefits coverge for NRT, which is lso vilble over the counter, lso influences these rtes. Notbly, two-thirds of MHS enrollees with tobcco dependence who filled n NRT prescription through the MHS lso filled prescription for bupropion, rte tht ws twice s high s the commercil nd Medicid popultions nd four times s high s the VA. CONCLUSIONS We compred treted prevlence nd high-level utiliztion mesures of ptients in four lrge helth insurnce systems in the U.S. We found considerble vrition cross the four ptient popultions in the prevlence of eight chronic conditions. These differences, t times, highlight the chllenges fced by ech helth insurnce system nd indicte tht tilored mngement, trcking, nd tretment pproches my be required. Applying the sme criteri to select ptients with ech of these diseses produced considerbly different rtes in ech popultion. For the mjority of the conditions, the ge/ sex djusted prevlence rtes were highest in the VA nd Medicid popultions. To some extent, our observtions re consistent with prior expecttions bout higher levels of severity of chronic illness mong the two progrms. Our study lso highlights tht government progrms ber much greter shre of common chronic illnesses cross the four popultions. Medicid beneficiries hd the highest hospitliztion rtes in four of the six conditions where hospitliztion rtes were mesured s the indictor. As for 30-dy redmissions, the VA rtes were significntly higher thn the rtes in the other three groups, result tht wrrnts further investigtion. It ws not surprising tht commercilly insured ptients hd the lowest prevlence rtes for the mjority of the conditions, given tht they re reltively helthy popultion, while differences my represent helthy worker effect. The MHS, which is lso employment-bsed, hd low prevlence rtes with two exceptions, childhood sthm nd hypertension. Similrly, the high rtes of depression nd severe mentl illness in the VA popultion were consistent with reports tht more thn 20% of VA service users re ffected by either depression or schizophreni. 16 This study elucidtes res of service needs mong the helth insurnce systems. MILITARY MEDICINE, Vol. 174, September 2009 941
While these results were consistent with differences in the ptient popultion or previous literture, there were some unexpected results. For exmple, the high rte of hypertension in the MHS nd the VA popultions ws nerly double the rte in the commercil popultion. However, the VA nd MHS rtes more closely resemble estimtes of ctul hypertension prevlence in the generl popultion, lthough mny cses within the generl popultion re undignosed. 17 If screening rtes re eqully effective cross the systems, then the MHS nd VA my hve higher percentge of ptients with hypertension. If screening is more effective, these systems my hve dignosed more ptients with high blood pressure. In ddition, hypertension rtes my be overstted given the definition of hypertension ws bsed on the presence of one outptient dignosis of hypertension nd were unble to confirm this dignosis using medicl records. Other crdiovsculr diseses revel contrsts. With high prevlence nd low hospitliztion the Medicid popultion reflects greter need for stroke rehbilittion services, while the other systems my hve lrger proportions of cute stroke events. With lower prevlence nd higher ED visit rtes MHS, commercil, nd Medicid reflect higher proportion of cute ischemic hert disese events, while the VA, with high prevlence nd low ED visit rtes, reflects greter need for rehbilittion services. There re severl limittions of this nlysis. All of the estimtes of prevlence were bsed on dministrtive dt nd were subject to the ssocited bises. Therefore, the estimted treted prevlence rtes in this study my not be the sme s prevlence rtes identified in other sources such s surveys. The dt elements were similr between the dt sets, but the number of dignostic fields vilble in ech of the dt files vried from 2 to 15. Sensitivity testing, by reducing the number of dignoses to the minimum number vilble in ll dt files (2) reveled tht more dignoses yielded more ptients, lthough the gins were not lrge. For exmple, when the number of possible dignostic fields exmined ws constrined to two, the undjusted sthm prevlence rte in the MHS dropped from 17.96 to 17.43. While ll of the results were stndrdized to the 2000 U.S. popultion distribution, djusting for ge nd gender my not ccount for other differences mong the systems. Multimorbidity could be significnt fctor in the observed differences. We refrined from djusting for comorbidities s the intent of this study ws to pply common definition of ech condition in ech system, nd then to compre the differences in utiliztion rtes nd prevlence for ech condition within ech system. Other fctors including socioeconomic fctors, benefit pln chrcteristics, nd ccess to cre my lso ccount for the observed differences in utiliztion nd prevlence. When the ge/sex distribution of the insurnce system differs significntly from the popultion (census), bis cn be introduced when compring stndrdized rtes. However we used direct stndrdiztion, which is less subject to this type of bis thn indirect stndrdiztion. 18 In our study, the only system tht differs significntly from the popultion is the VA. Age/sex djustment hd little effect on the rtes in the other insurnce systems nd little effect on the prevlence rtes in four VA conditions: hypertension, depression, severe mentl illness, nd stroke. Additionlly, there re likely different physicin finncil incentive structures cross the dtbses, such s differing mix of fee-for-service clims nd encounters. These reimbursement rrngements cn influence the mount of informtion (e.g., number of clims, number of dignoses) tht ppers in the clims files. 19 For exmple, higher percentge of encounter dt (versus fee for service) cn bis the clculted prevlence nd utiliztion rtes downwrd. Finlly, VA ptients my hve utilized services not cptured by the VA system, which could hve influenced the VA rtes ( downwrd bis) in this nlysis. In prticulr, urgent or emergent events where vetern will typiclly be tken to the nerest fcility, such s ischemic hert disese nd stroke, my hve been underestimted in the VA system. In ll systems, use of other helth insurnce my occur (i.e., spouse coverge, other employer coverge, nd to lesser extent, Medicre) resulting in services delivered to ptients within the system tht re not cptured by the clims in the system. The results of this study provide n empiricl nlysis of mesures of chronic disese prevlence rtes nd utiliztion mong four insurnce systems nd ultimtely rise further questions for study. The estimted prevlence nd utiliztion rtes ssocited with eight chronic conditions demonstrte helth cre service needs nd cn inform res including benefit pln design nd performnce mesurement. 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