Factors associated with potentially inappropriate drug utilization in a sample of rural community-dwelling older adults

The American Journal of Geriatric Pharmacothera~y

SJ Blalock et al

Factors Associated with Potentially Inappropriate Drug Utilization in a Sample of Rural Community-Dwelling Older Adults Susan J. Blalock, PhDI;John E. Byrd, PharmDI; Richard A. Hansen, PhDI;Thespina J.Yamanis,MPH2; Katherine McMullin, MPH2; Brenda M. DeVellis, PhD2; Robert E DeVellis, PhD2;A.T. Panter, PhD3; Ariane K. Kawata, MA3; Lea C.Watson, MD, MPH4; and Joanne M.Jordan, MD, MPH 4 ISchool of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, 2Schoolof Pubhc Health, University of North Carolina, Chapel Hill, North Carolina, 3Departrnent of Psychology, University of North Carolina, Chapel Hill, North Carolina, and "4Schoolof Medicine, University of North Carolina, Chapel Hill, North Carolina

ABSTRACT Background: Many mcdlcatlons prcscnt spcclal risks whcn uscd by oldcr adults (1C, thosc agcd >65 ycars) and arc consldcrcd potcntlally lnapproprlatc for this population. Thc Bccrs crltcrla arc oftcn uscd to ldcntlfy such mcdlcations. Past rcscarch has documcntcd that usc o f Bccrs drugs is common among oldcr adults. Objective: Thc aim o f this work was to cxamlnc factors assoclatcd with potcntlally lnapproprlatc drug usc among rural communlty-dwclhng oldcr adults using a conccptual framcwork adaptcd from thc Andcrscn-Ncwman bchav1oral modcl o f hcalth scrvlcc usc. Methods: This was a populatlon-bascd, cross-scctlonal survcy. Data wcrc collcctcd via facc-to-facc homc lntcrVlCWSbctwccn 2002 and 2004. Rural communlty-dwclhng oldcr adults rcsldlng in a slnglc county in North Carolina wcrc cllglblc. Potcntlally lnapproprlatc drug usc was opcratlonallzcd using thc Bccrs crltcrla. Data conccrnlng prcdisposing (lC, agc, scx, racc, cducatlon, and marital status), cnabllng (lC, social support and lnsurancc status), nccd (lC, dlsablhty and history o f major dcprcsslon, hypcrtcnslon, ostcoarthrltlS, back problcms, or othcr comorbldltlCS), and utilization factors (lC, numbcr o f mcdlcatlons uscd) wcrc collcctcd. Results: Data wcrc gathcrcd from 892 pcoplc, with information on mcdlcatlon usc avallablc for 800. Two hundrcd thlrtccn o f thcsc 800 participants (26.6%) uscd >1 Bccrs drug. Comparcd with individuals who uscd no Bccrs drugs, thosc who uscd >1 Bccrs drug rcportcd lower levels o f social support (odds ratio [OR], 0.94; 95% CI, 0.90-0.99) and hlghcr levels o f disability (OR, 1.48; 95% CI, 1.11-1.97), uscd morc mcdlcatlons (OR, 1.07; 95% CI, 1.01-1.13), and wcrc morc llkcly to havc a history o f major dcprcsslon (OR, 1.67; 95% CI, 1.05-2.66), hypcrtcnslon (OR, 1.58; 95% CI, 1.07-2.33), ostcoarthrltlS (OR, 1.58; 95% CI, 1.09-2.29), and back problcms (OR, 1.72; 95% CI, 1.19-2.47). Conclusion: As suggcstcd by thc Andcrscn-Ncwman modcl, thc risk ofpotcntlally lnapproprlatc drug usc is hlghcst among thosc with thc grcatcst mcdlcatlon nccds, as cvldcnccd by poorcr hcalth status in this samplc o f rural communlty-dwclhng oldcr patlcnts. ( A m f Gerzatr Pharmacother. 2005;3:168-179) Copyright © 2005 Exccrpta Mcdlca, Inc. Key words: cldcrly, drug utilization, approprlatcncss, Bccrs crltcrla, Andcrscn-Ncwman modcl.

Acceptedfor publicationJune 29, 2005 Printed in the USA Reproduction in whole or part is not permitted

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September 2005

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S J Blalock et al

INTRODUCTION

With the aging o f the US population, people are taking more medications than ever before. 1,2 This is especially true o f older adults. Although Americans aged >65 years account for <15% o f the US population, they consume nearly one third o f all prescription drugsJ This high rate o f use, combined v~qth age-related physiological changes in the way drugs are absorbed, distributed, metabolized, and excreted, makes older adults particularly vulnerable to medication-related problems. 4 Many medications present special risks when used by older adults (lC, those aged >65 years) and, therefore, are considered potentially inappropriate for this population. ~ Although there is no gold standard for assessing inappropriate medication use, 1 o f 2 general approaches is usually taken. 6 The first approach involves the use o f ~mphc~t criteria. ~ Because this approach requires clinical judgment to apply, i t l S often impractical to use in large, population-based studies. 6 The second approach involves the use o f exphc, t cr, term. T w o sets o f explicit criteria have been developed using expert consensus panels: the Beers criteria 4 and the Canadian criteria. 7 Both sets o f criteria identify medications--both prescription and over-the-counter d r u g s - - t h a t may pose greater risks than benefits when used by older adults. Here, we focus on the Beers criteria, which have received the greatest attention from US investigators. The original Beers criteria were created in 1991 to address potentially inappropriate prescribing in the nursing h o m e setting. 8 Using a modified Delphi technique, a panel o f experts reached consensus on a list o f 30 criteria to identify medications that would be harmful or had the potential for harm in older adults} The original Beers criteria have been updated t w i c e - - i n 1997 and in 2003.4,9 These revisions have increased the applicability o f the criteria for the study o f medication u t l h z a t l o n in c o m m u n i t y settings.

Research has documented that many older adults use medications designated as potentially inappropriate for this population, with the reported prevalence o f using >1 Beers drug ranging from 13% to 28%. 1° 14 For example, in 2004, Curtis et a111 reported on the extent o f potentially inappropriate prescribing based on a retrospective cohort analysis o f claims data from a national pharmacy benefit manager. They found that 21% o f the subjects in the database filled a prescription for >1 drug on the 1997 Beers hst. Similarly, using data from the Duke Epidemiologic Studies o f the Elderly, a 10-year prospective cohort study o f older adults hvlng in N o r t h Carolina, Hanlon et a112,13 found that -20% o f study participants used >1 potentially inappropriate drug.

The American Journal of Geriatric Pharmacotherapy

Glvcn thc prcvalcncc o f potcntlally inappropriate drug use a m o n g older adults, it is important to identify factors that increase this risk. Several studies have exam1ned this lSSUC. 15 20 For example, based on an analysis o f data from the 1996 Medical Expenditure Panel Survey, Zhan et al 1~ found a significantly higher risk o f potentially inappropriate drug use a m o n g persons in poorer health and a m o n g those taking more medications. After controlling for other factors, individuals reporting p o o r health were - 6 times more likely to be taking an inappropriate medication than were individuals reporting excellent health ( P < 0.05), and those taking more than the me&an n u m b e r o f medications were 3 times more likely to be taking an inappropriate medication than were those taking fewer medications ( P < 0.05). 1~ Similarly, using data from the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey, Goulding 16 found that the risk o f potentially inappropriate drug use increased with the n u m b e r o f drugs that the panent was taking. Compared with individuals taking only 1 medication, individuals taking 2 medications were 2.6 times more likely to be taking an inappropriate medication. 16 This risk increased with each additional medication, so individuals taking 6 medications were >6 times more likely to be taking an inappropriate medication compared with individuals taking only 1 medication. 16 The purpose o f the study described in this report was to examine factors associated with potentially inappropriate drug use a m o n g rural community-dwelhng older adults using a conceptual framework adapted from the Andersen-Newman behavioral model o f health service use.21, 22 METHODS Andersen-Newman

Model Modification

Since ltS original development more than 30 years ago, the Andersen-Newman model has been used to guide numerous studies investigating health care utilization. At the individual level, the model outlines 3 types o f predictors o f health services utilization: predisposing factors, enabling factors, and need. Pred,spos, ngfactors are individual characteristics believed to influence the use o f health care services, including age, sex, race, education, marital status, socioeconomic status, and employment. E n a b h n d factors are resources that facilitate utlhzatlon, including monetary resources, health insurance, social support, and access to care. Finally, need reflects objective and subjective health status, including ability to perform a c t i v i t i e s o f dally living and psychological, as well as physical, well-being. Past re-

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S J Blalock et al

search using tho Andorson-Nowman model has found need-related factors to bo most conslstontly assoclatod with tho utilization o f health sorvlcos. 23 Although the Andorson-Nowman model was not developed specifically to examine tho quality or appropriatoness o f health services utilization, it has been applied to this issuo by lnvostlgators oxamlnlng tho utilization o f potentially inappropriate medications. 13,2°,24 For oxamplo, Hanlon ot al,2° using a modification o f the model, found that the risk o f potontially inappropriato modication use lncroasod with the number of proscription modications used ( 2 4 drugs adjustod odds ratio [OR], 3.69; 95% CI, 2.63-5.17), tho number of health care visits made during tho previous yoar, prior use o f a potontlally inappropriato medication (adjustod OR, 3.75; 95% CI, 2 . 9 0 4 . 8 5 ) , and continuity of care (adjustod OR, 2.03; 95% CI, 1.32-3.13). It is notable that, ofthoso 4 predictor variablos, the first 3 reflect utilization por so, rathor than tho typos ofprodisposlng, enabling, and need factors specified by tho Andorson-Nowman model. Therefore, in tho current study, wo modified tho model by adding utilization as a distinct type ofprodlctor variable. Wo formed 2 hypotheses. First, wo reasoned that, after controlling for predisposing, enabling, and need factors, lncroasod utilization o f modlcatlons would bo associated with an increased risk o f potentially inappropriate utilization. Second, wo hypothoSlzod that lncroasod modlcatlon utilization would modlato tho rolatlonshlp botwoon potontlally lnapproprlatO utilization and tho predisposing, enabling, and need factors examined.

Study Design and Participants This was a populatlon-bascd, cross-scctlonal survcy. Data for this study woro collected botwoon 2002 and 2004 as part o f a larger study o f depression in ostooarthritis (OA). Participants in tho study originally had been rocruitod botwoon 1991 and 1998 for a study oftho opldomlology o f OA using population-based random sampling methods. To bo eligible for tho original opldomlology study, individuals had to bo: civilian, noninstitutionalizod, whito or black, aged >45 years, a rosident o f any o f 6 townships in a county in N o r t h Carolina, and physically and mentally capable o f complotlng study procoduros which involvod taking part in 2 h o m e intorviows and a visit to a local medical clinic. Blacks woro purposely ovorsamplod because tho original projoct was designed as a long-term study ofothnlc differences in OA occurrence and progression. Participants in tho original opldomlology projoct woro sent a letter doscrlblng tho now study and inviting

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tholr participation. Tho letter was followod by a telephone call to answor any quostlons potontlal participants might have and, if they agreed, schedule an inh o m e intorviow. Tho study was approved by tho institutional roviow board o f tho School o f Modicino at tho Univorsity o f N o r t h Carolina at Chapel Hill.

Data Collection Methods All interviews wcrc conducted in person, usually in tho participant's home, and typically required 75 to 90 mlnutos to comploto. Intorviowors woro tralnod on lntorvlowlng tochnlquos, othlcal rosponslbllltlOS, and study protocols. All quostlons woro road to participants and, for quostlons with fixod-cholco rosponso options, participants woro shown cards with tho rosponso options llstod. I f a participant could not road, tho lntorvlowor road tho rosponso options for oach quostlon aloud. Independent Variables Indopondont varlablos woro groupod into four catogorlos: prodlsposlng factors, onabllng factors, nood factors, and utilization factors. Flvo prodlsposlng factors woro assossod: ago (yoars), sox (0 = malo, 1 = fomalo), raco (0 = whlto, 1 = black), oducatlon (yoars), and marital status (0 = not currontly marrlod, 1 = currontly marrlod). T w o onabllng factors woro oxamlnod--soclal support and lnsuranco status. Social support was assossod by a 4-1tom vorslon o f Doan and Lln's 1977 moasuro rogardlng porcolvod social tlOS. 25 Tho vorslon usod in this study was adaptod for oldor pooplo with arthritis. 26 Participants woro askod how froquontly thoy woro bothered by not having a closo companion, not SOolng poople to w h o m thoy folt closo, not having onough closo frlonds, and not having somoono who showod thorn lovo and affoctlon. Rosponso options rangod from 1 (all o f tho t l m o ) t o 5 (never). Insurance status was coded as a dichotomous varlablo (0 = no insuranco or Modicaro only, 1 = insuranco in addition to Modicaro). This dichotomous coding was used because individuals with no insurance or Medicare only would have had no coverage for prescription modlcanons at tho tlmo tho survey was conducted, whoroas individuals with supplemental insurance would bo more likely to have prescription coverage. Six need-related variables woro assessed: disability; and history o f major depression, hypertension, OA, back problems, or other comorbldltlOS. These spocific health problems woro selected because they woro prevalent in our sample and because many o f t h o modlcatlons lncludod in tho Beers crltorla aro used to treat these conditions.

S J Blalock et al

Disability was asscsscd using thc 20-1tcm Hcalth Asscssmcnt Qucstionnairc ( H A Q ) . 27 Participants wcrc askcd to ratc thc dcgrcc o f difficulty cxpcricnccd whilc pcrforming diffcrcnt activitics o f dally laving. Rcsponscs arc rccordcd on a 4-point scalc ranging from 0 (without any difficulty) to 3 (unablc to do). Itcms arc groupcd into 8 catcgorics, and catcgory scorcs arc adjustcd for thc nccd for assistancc from othcrs or thc Usc o f assistivc devices. An ovcrall disability indcx is found by calculating thc mcan across thc 8 catcgorlcs, with thc ovcrall lndcx having a posslblc rangc o f 0 to 3. Thc H A Q has bccn uscd cxtcnslvcly, and substantial data support its rcllablllty and validity. 28 History o f major dcprcsslon was asscsscd using thc automated Composite International Diagnostic IntcrVlCW ( C I D I ) , vcrslon 2.0 for DOS (World Hcalth Organization, Gcncva, Swltzcrland). Thc C I D I is a structured psychiatric interview that links symptoms dcscrlbcd by participants to D~agnost~c and Statistical M a n u a l of Mental D~sorders, Fourth Edition, and International Classification of D~seases, N~nth Rews~on, diagnostic criteria for psychiatric diagnoses. This intcrvicw was dcsigncd to bc administcrcd by carcfully tralncd, noncllnlclan lntcrvicwcrs. Thc automatcd vcrslon is p r o g r a m m c d to computc scorcs for participants and thcn assign a diagnosis bascd on an intcrnal algorithm. The rchabihty and validity o f this instrument havc bccn supportcd in scvcral studies. 29 31 To asscss thc prcscncc or history o f othcr hcalth problcms, participants wcrc askcd ifthcy wcrc currcntly cxpcricncing, or had cxpcricnccd in thc past, any o f 46 diffcrcnt conditions. This information was uscd to form indicators for thc prcscncc/history o f 3 specific conditions: hypertension, OA, and back problcms (0 = no history o f condition, 1 = current or history o f condition). Information conccrning thc rcmaining conditions was uscd to crcatc a comorbldlty lndcx bascd on thc Charlson Comorbidity Indcx (CCI). 32 Fourtccn conditions wcrc sclcctcd a priori for inclusion in this index, to parallel those included in the CCI: chronic bronchitis, emphysema, stroke, myocardial infarction, othcr hcart troublc, circulation problcms, stomach ulccr, Alzhcimcr's discasc, multiplc sclcrosis, rhcumatold arthritis, dialysis or kidney failure, paralysis o f any kind, cancer, and diabetes mcllitus. Although i t would havc bccn possiblc to includc othcr conditions in thc comorbidity mcasurc dcvclopcd for thc prcscnt study, i t was dccidcd that i t would bc prcfcrablc to modcl thc mcasurc aftcr thc C C I bccausc o f its wide use in thc litcraturc. For thc indcx dcvclopcd for thc prcscnt study, cach o f thc first 10 c o n d i t i o n s w a s scorcd as "1" if i t

The American Journal of Geriatric Pharmacotherapy

was currcntly prcscnt. A history o f clthcr myocardial infarction or strokc was also scorcd as "1" cach. Bascd on wcights r c c o m m c n d c d by Charlson ct al, 32 thc last 4 conditions wcrc cach scorcd as "2" if thcy wcrc currcntly prcscnt. Thus, this variablc had a possiblc rangc o f 0 to 18. Only 1 utilization factor, numbcr o f medications uscd, was asscsscd. D u n n g thc homc interviews, participants wcrc asked to rctrlcvc all o f the medications that thcy wcrc using currcntly, including both prcscrlptlon and nonprcscrlptlon mcdlcatlons. Thc lntcrvlcwcr rcVlcwcd thc mcdlcatlons with participants and rccordcd thc namc and dosagc rcglmcn for cach mcdlcatlon. Medication utlhzatlon was opcratlonahzcd as the numbcr o f unlquc mcdlcatlons uscd by thc participant. In thc rcgrcsslon analyscs dcscrlbcd in thc following subscctlon, thc n u m b c r o f Bccrs drugs takcn was subtractcd from the total n u m b e r o f drugs taken to avoid inflating the association between these 2 constructs. Dependent Variable Thc updatcd 2003 Bccrs crltcrla wcrc uscd to dcfinc potentially inappropriate medication utlhzatlon. These cratcrla ldcnnfy thc following mcdlcatlons/mcdlcanon classes that arc potentially inappropriate to use in older adults: amlodaronc,* amltrlptyllnc, amphctamlncs and anorexic agents,* antlchollncrglcs and antihistamines, barblturatcs (cxccpt phcnobarbltal), long-acting bcnzodlazcplncs, short-acting bcnzodlazcplncs abovc spcclficd dosagcs, chlorpropamldc, clmctldinc,* clonldlnc,* cyclandclatc,* dcsiccatcd thyroid,* digoxin in doscs >0.125 m g / d , diphcnhydraminc, short-acting dipyridamolc,* disopyramidc, doxazosin,* doxcpin, ergot mcsyloids, cthacrynic acid,* ferrous sulfate in dosages >325 m g / d , * dally fluoxctinc,* flurazcpam, gastrointestinal antispasmodics, guancthidinc,* guanadrcl,* indomcthacin, isoxsuprinc,* kctorolac,* mcpcridinc, m c p r o b a m a t c , mcsoridazinc,* mcthyldopa, mcthyltcstostcronc,* mincral oil,* musclc rclaxants, shortacting nifcdipinc,* nitrofurantoin,* longer half-life NSAIDs not sclcctivc for cyclooxygcnasc-2,* orphcnadrinc,* pcntazocinc, propoxyphcnc, rcscrpinc in doscs >0.25 m g / d , * stimulant laxanvcs,* thioridazinc,* ticlopidinc, and trimcthobcnzamidc. Thc 2003 Bccrs critcria also idcntify thc usc o f unopposcd cstrogcn as potcntially inappropriatc. Howcvcr, bccausc data for this study wcrc collcctcd bcforc thc rclcasc o f data from thc Womcn's Hcalth Initiative trial 33 conccrning thc usc of

*This drug or class of drugs was added in the 2003 revision of the Beers criteria

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S J Blalock et al

unopposed estrogen, wc did not include estrogen as a Beers drug. Variables wcrc created to index both the use o f > l Beers drug and the number of Beers drugs used.

Analytic Strategy Hierarchical logistic regression analysis was used to examine factors associated with the use o f a l potentially inappropriate drug, as classified by the Beers criteria. Predisposing factors (1¢, age, sex, race, educanon, and marital status) were entered into the model in step 1. Enabling factors (1¢, insurance status and social support) wcrc cntcrcd in step 2. Nccd factors (le, disability; history o f major dcprcsslon, hypcrtcnslon, OA, and back problcms; othcr comorbldltlCS) wcrc cntcrcd in stcp 3. Finally, thc numbcr o f drugs thc participant was taking, not counting Bccrs drugs, was cntcrcd into thc modcl in stcp 4. Colhncarity among lndcpcndcnt varlablcs was asscsscd by cxamlnlng Pcarson corrclatlons, phi cocfficlcnts, and polnt-blscrlal corrclatlons. Modcl fit was asscsscd by thc Hosmcr-Lcmcshow goodncss-of-fit tcst. 34 All analyscs wcrc conductcd using SAS/STAT softwarc, vcrslon 8.2 (SAS InstltUtC, Inc., Cary, North Carolina). RESULTS Study Participants A total o f 2172 individuals from the original epldemlology project were invited to participate in the new study. This represented -57% o f the original sample. All o f these individuals had completed >1 interview for the original project. O f these individuals, 71 were found to be ineligible for the depression study, either because they had died since the time o f last data collection (n = 38) or because they had moved away from the area (n = 33). O f the remaining 2101 individuals, 69 could not be located, 52 had not yet been contacted at the time o f this analysis, and 488 declined to be interviewed. Interviews were completed with the remaining 1492 individuals, resulting in a participation rate o f 71.0%. Because this paper examines the use o f potentially inappropriate medications among older adults, the data set was hmlted to 892 participants who were aged >65 years at the time o f data collection from year 2002 to year 2004. Data concerning medication utilization were available for 800 o f these individuals. As shown in Table I, study participants had a mean (SD) age o f 74.6 (6.6) years and a mean (SD) education o f 12.3 (4.7) years. Most participants were female (69.7% [n = 622]), white (70.5% [n = 629]), and taking a mean (SD) o f 6.9 (3.8) medications. O f the 800 participants for whom medication information was available, 213 (26.6%) used a

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total o f 268 Beers drugs. One hundred SlXty-nlnc participants uscd 1 Bccrs drug; 36 uscd 2 Bccrs drugs; and 8 uscd >3 Bccrs drugs. Table I I shows thc usc o f thc mcdlcatlons/mcdlcatlon classcs spcclficd in thc Bccrs crltcrla. Thc most frcqucntly uscd individual Bccrs drugs wcrc propoxyphcnc (n = 36 [4.5%]), clonldlnc (n = 24 [3.0%]), and naproxcn (n = 19 [2.4%]). According to blvarlatc analyscs, thosc taking >1 Bccrs drug rcportcd thc following, comparcd with thosc taking no Beers drugs: less social support (P = 0.02); use of morc mcdlcanons ovcrall (P < 0.001); hlghcr disability lndcx (P < 0.001); grcatcr hkchhood o f history of major dcprcsslon ( P < 0.001), hypcrtcnslon (P < 0.001), OA (P < 0.001), and back problcms (P < 0.001); and hlghcr comorbldlty lndcx (P = 0.001) (Table I). Thc corrclatlons among prcdlctor varlablcs wcrc modcst, with the strongcst corrclatlon bcva~ccn thc dlsablhty mcasurc and thc comorbldlty lndcx (r = 0.40).

Potentially Inappropriate Medication Utilization Table I I I prcscnts thc rcsults o f thc stcpwlsc rcgrcsslon analyses predicting the use o f potentially inappropriate me&canons. O f the predisposing and enabhng factors entered in steps 1 and 2, only social support contrlbuted significantly to the model in the stepwlse analysis. Higher levels o f support were associated with a decreased risk o f potentially inappropriate me&canon utilization (OR, 0.94; 95% CI, 0.90-0.99). Five o f the 6 need variables entered in step 3 were statistically significant in the stepwlse analysis. The risk o f potentially inappropriate utilization was greater among individuals with a history o f major depression (OR, 1.67; 95% CI, 1.05-2.66), hypertension (OR, 1.58; 95% CI, 1.07-2.33), OA (OR, 1.58; 95% CI, 1.09-2.29), and back problems (OR, 1.72; 95% CI, 1.19-2.47), and increased with higher levels o f disability (OR, 1.48; 95% CI, 1.11-1.97). In step 4, the risk o f potentially mappropriate utlhzatlon increased with the number o f medlcanons used (OR, 1.07; 95% CI, 1.01-1.13). Finally, after controlhng for the number o f me&canons used, only 2 factors (le, history o f back problems and disability) remained statistically significant, providing partial support for the hypothesis that utlhzatlon mediates the relationship beVaTeenthe use o f potentially inappropriate me&canons and other factors in the Andersen-Newman model. DISCUSSION Thrcc major findings cmcrgcd from this study. First, 26.6% o f study parnclpants wcrc using >1 potcntlally lnapproprlatc drug as dcfincd by thc Bccrs crltcrla. This

S J Blalock et al

The American Journal of Geriatric Pharmacotherapy

Table I. Charactermucs of study participants.*

Characterlstlc$

All Participants (N 892)

Participants on No Beers Drugs (n 587)

Participants on >1 Beers Drug (n 213)

p:l:

Age, mean (SD), y

74 6 (6 6)

74 5 (6 9)

742 (6 I)

0SI

Education, mean (SD), y

12 3 (4 7)

124 (4 8)

I 8 (45)

011

Sex, no (%) Female Hale

622 (69 7) 270 (30 3)

398 (67 8) 189 (322)

51 (70 9) 62 (29 I)

Race, no (%) White Black

629 (705) 263 (29 5)

411 (700) 176 (30 0)

53 (718) 60 (28 2)

Marital status, no (%) Unmarried Married

480 (53 8) 412 (46 2)

304 (51 8) 283 (48 2)

22 (57 3) 91 (427)

Insurance In addition to Medicare, no (%)

693 (77 7)

454 (77 3)

165 (77 5)

097

Social support score, mean (SD)§

17 0 (3 2)

17 2 (3 I )

165 (35)

002

0 8 (0 7)

0 7 (0 7)

I 0 (0 7)

<0001

(I I 2) (63 2) (55 4) (25 0)

46 (21 6) 62 (76 I) 52 (71 4) 91 (427)

<0 001 <0 001

Disability index, mean (SD) II

041

062

017

Medical history, no (%) Major depression Hypertension Osteoarthntm Back problems

124 601 530 270

Comorbl@ty index, mean (SD) IT

I 34 (I 46)

I 19 (I 35)

61 (I 65)

0001

6 9 (3 8)

6 I (3 4)

7 8 (3 8) #

<0 001

No off medications, mean (SD)

(I 3 9) (67 4) (59 4) (30 3)

66 371 325 147

<0001 <0001

÷Ninety two participants had missingmedication data f Rangesof continuous variableswere as follows age,65 100 years,education, 0 ~ I years,social support, score of 4 20, disability,index of 0 3, comorb@ty, index of ~18, number of medications,0 23 $ Compares parhcipants taking no Beers drugs with parbcipantstaking >1 Beers drug Values based on Student t tests for conbnuous variables and X2 tests for categoricalvariables Social support was assessedby a 4 item version of Dean and Lm's 1977 measure regarding percewed social ties 26 and was adapted for older people with arthntm 27 Participantswere asked how frequently they were bothered by not having a close compamon, not seeing people to whom they felt close, not having enough close friends, and not having someone who showed them love and affechon Indwldual response options ranged from I (all of the time) to 5 (never) IIDmablhtywas assessedusingthe 20 item Health AssessmentQue~honnalre29Participantswere askedto rate the degree of @fficultyexperienced performing @fferent achvltlesof dally hvmg,usingthe mean to calculate an overall dmablhtyindex ¶Participants were asked if they were currently experiencing,or had experienced in the pa~t,certain me@calcon@tlons Information was used to create a comorbl@ty index based on the Charlson Comorb@ty Index 33 #Value does not include Beers drugs

finding is conslstcnt with prcvlous rcscarch, whcrc thc prevalence o f potentially inappropriate drug use has ranged from 13% to 28%. 1° 14 A l t h o u g h a n u m b e r o f drugs were added to the revised Beers list, others were chmlnatcd, so it is n o t surprising that thc prcvalcncc rates remained u n c h a n g e d over time. However, the stablhty o f these rates across studlcs and across tlmc sug-

gest that potentially inappropriate drug use a m o n g older adults continues to be a major public health concern, despite the substantial attention it has received since pubhcatlon o f the original Beers criteria m o r e than a decade ago. To address this problem, a better understanding o f the determinants o f potentially inappropriate prescnblng is needed.

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Table II. Prevalence of specific Beers medications and medication classes used by study participants (N = 892).

Medication/Medication Class*

Propoxyphene Longer half-hfe non COX-2~electlve NSAIDs

Naproxen Neloxlcam Nabumetone Suhndac Dlflunlsal Oxaprozln Muscle relaxants and antispasmodics Cyclobenzapnne Oxybutynln Methocarbamol Cansoprodol Tizanldlne Antlchohnerglcs and antihistamines Diphenhydramlne Hydroxyzlne Promethazlne Chlorphenlramlne Clemastlne Doxylamlne Tnprohdlne Clon@ne Amlodarone

Amltrlptyllne Daily fluoxetlne Doxazosln

Long acting benzodlazeplnes Chlordlazepoxlde Dlazepam Gastrointestinal antispasmodics Dicyclomlne Hyoscyamlne Nitrofurantoln

Indomethacln Short acting benzodlazeplnes above specified dosages Alprazolam Lorazepam Temazepam Stimulant laxatives

Bisacodyl Casanthranol Senna Doxepln Cimetldlne

No (%) of Patients Using Medication~Class

36 (4 0) 34 (3 8) 19 (2 I) 8 (0 9) 3 (0 3) 2 (0 2) I (0 I) I (0 I) 31 (3 5) 13 (I 5) 9 (I 0) 5 (0 6) 3 (0 3) I (0 I) 27 (3 0) 12 (I 3) 5 (06) 4 (04) 3 (03) I (0 I) I (0 I) I (0 I) 24 (2 7) 16 (I 8) 15 (I 7) 14 (I 6) 13 (I 5) 10 (I I) 5 (0 6) 5 (06) 7 (0 8) 5 (06) 2 (0 2) 7 (0 8) 6 (0 7) 5 (06) 2 (0 2) 2 (0 2) I (0 I) 5 (0 6) 2 (0 2) 2 (0 2) I (0 I) 3 (0 3) 2 (0 2)

Severity Rating

Low High

High

High

Low High High High Low High

High

High High High

High

High Low (continued)

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S J Blalock et al

The American Journal of Geriatric Pharmacotheral~y

Table II. (Continued)

Me@cation/Me@cation Class*

No (%) of Patients Using Me@cation/Class

Seventy Rating

2 (o 2) 2 (o 2) 2 (o 2) (o) (o) (o) (o) (o) (o) (o)

High Low High High Low High High High High High

Desiccated thyroid Short-acting @pyndamole Ketorolac Chlorpropamlde

Ferrous sulfate in dosages >225 mg/d Heper@ne Hethyldopa

Mineral oil Short-acting n@dlplne Pentazoclne

COX 2 cyclooxygenase 2 *Drugs and classesshown in italics were added in the 2003 revision of the Beers criteria Severity ratings are those pro vlded in the 2003 revision of the Beers criteria

Table III. Multlvarlable logistic regression model examining the associations between predisposing, enabling, need, and utilization factors and the use of potentially inappropriate medications as defined by the 2003 Beers criteria (N = 78 I).* Stepwlse Hodelt Full Hodel$ Variable

OR

95% CI

Step I predisposing factors Age Sex Race Education Hantal status

098 1 14 087 097 081

096 078 061 093 056

Step 2 enabling factors Insurance status Social support

102 094

068 152 090 099

LR Z 2 for Step

OR

95% CI

098 078 106 098 090

095 I01 051 120 071 157 094 102 060134

I II 096

073 169 091 101

59 41 46 72 O0 39

0 9 9 Q 53 0 9 4 ~ I0 I 0 0 ~ 13 I 1 9 ~ 47 087 113 104 I 86

07

I01

7 24 I01 167 125 I00 117 5 26

Step 3 need factors Hajor depression Hypertension OsteoarthrltlS Back problems Comorbl@ty index Disability

67 58 58 72 03 48

Step 4 utilization No of drugs used

107

59 56§ I 05 I 07 109 II 9 091 III

266 233 229 247 117 197 5 8311

101 113

I 13

OR odds ratio, LR likelihood ratio *Hosmer and Lemeshow goodness o~fit ten for full model, 590 (P 066) tWithn each s~ep,ORs and CIs were adJustedfor all variables included in that s~ep and in preceding s~eps SOPs and CIs were adJustedfor all variables included in the full model ~P < 0001 lip < 005

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Second, study findings support use o f the modified Andersen-Newman behavioral model o f health care service use to better understand factors associated with potentially inappropriate drug utlhzatlon. Before number o f medications used was entered into the regression model, need variables were the strongest predictors o f potentially inappropriate m e & c a n o n utilization, with 5 o f the 6 need variables contributing significantly to the model. However, after the n u m b e r o f me&canons was added to the regression model, the significance o f most o f the need variables was reduced, providing partial support for the hypothesis that m e & c a n o n utlhzatlon per se mediates the relationship between need factors and inappropriate m e & c a n o n utlhzatlon. This observation may help to clarify inconsistencies in the literature. In past research using the AndersenN e w m a n model to study utlhzatlon o f health care services, need factors have consistently been the strongest predictors o f utilization. 23 The literature examining Utlhzatlon o f potentially inappropriate me&canons is less consistent. The only variable consistently associated with the use o f potentially inappropriate me&canons has been the n u m b e r o f me&canons used. 14 In contrast, need factors, such as perceived health status and self-reported health problems, have been associated with inappropriate m e & c a n o n use in some studies, 13,15,35 but not in others. 2° In examining the relationship between need factors and inappropriate medication use, most studies have controlled for the n u m b e r o f medications used. However, if the effect o f need factors on inappropriate m e & c a n o n use is mediated by increases in m e & c a n o n utlhzatlon per se, this analytic strategy would obscure these indirect relationships. Therefore, we beheve it is desirable to examine the association between need variablcs and inappropriatc mcdlcatlon utlhzatlon, both with and without controlling for utilization pcr sc. The observation that utlhzatlon per se may mediate the relationship between need factors and inappropriate medication utilization raises an important question. Must lncrcascs in utlhzatlon lncvitably lcad to lncrcascs in inappropriate utlhzatlon? Or, alternatively, are there conditions under which high levels o f utilization are not associated with high levels o f inappropriate utihzanon? It seems reasonable to speculate that the relationship between utlhzatlon and lnapproprlatc utlhzatlon should be weakest when quality o f care is high. Thus, although not examined in this study, quality o f care may moderate the relationship between utlhzatlon and lnapproprlatc utlhzatlon. Evaluating this hypothcslzcd moderating relationship is an important area for future

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research. Quality indicators that might bc studlcd include the following: patient perceptions o f health care quality36; dchvcry o f p a t i c n t cducation conccrning the purposc o f prcscribcd mcdications, how to usc thcm, and expected sldc effects and adverse rcact10ns37; inclusion o f a hst o f all mcdlcatlons a patlcnt is taking in outpaticnt and hospital mcdical rccords37; documcntation o f thcrapcutlc rcsponsc37; mcdlcatlon thcrapy managcment by an lnterdlsclphnary team that includes a pharmacist38; pcrformancc o f pcriodic drug rcgimcn rcvicw37; availability ofpharmaccutical softwarc to support physician prcscribing39; and usc o f appropriatc mcdications in thc prcscncc o f spccific conditions (cg, pharmacotherapy for the treatment o f mild uncontrolled hypertension). 4° The final malor study finding that emerged from the current study was that, a m o n g the predisposing and cnabling factors cxamincd, only social support was associatcd with thc risk o f potcntially inappropriatc drug use. Participants with lower levels o f support were at grcatcr risk. This is thc first study o f which wc knou T that cxamlncs thc rclatlonshlp bctwccn social support and potentially inappropriate drug use. Therefore, thcrc is a nccd to dctcrminc whcthcr this finding can bc generahzed to other patient populations and, if so, t o better understand the nature o f this relationship. For cxamplc, docs social support facihtatc paticnt-providcr communication about mcdlcatlon? With rcspcct to thc prcdisposing factors cxamincd, thc lack o f significant associations observed in this study highlights additional inconsistencies in the hterature. Some studies have found associations between potentially inappropriatc drug usc and SOclodcmographlc charactcrlstlcs, such as sex and race, whereas others have not. 14 Thus, at the current time, it is not clear whether SOclodemographic charactcristics can bc uscd to idcntify high-risk groups. Several study limitations should be noted. First, partlclpants wcrc rcstrlctcd to rcsldcnts o f a slnglc county in N o r t h Carolina. Although population-based random sampling proccdurcs wcrc uscd, thc gcncralizability o f study findings to populations in other geographic areas is open to qucstlon. In this regard, however, the similarity o f our cstimatcs o f thc prcvalcncc o f potcntially inappropriatc drug usc to thosc rcportcd in prcvious studlcs is rcassurlng. Second, the Beers crltcrla only idcntify mcdications that arc potcntially inappropriatc for use in older patients in general. In a specific patient, there may be circumstances that warrant the use o f these medications. For example, a patient may not be able to tolerate other medications that are typically

S J Blalock et al

considered more appropriate for older patients. In addition, non-Beers drugs may have bccn tried previously and found ineffective. N o information was available to allow us to identify these unique instances. Third, wc assumed that the need-related variables examined in this study wcrc risk factors for potentially inappropriate drug utlhzatlon. However, this causal inference is speculative duc to the cross-sectional design o f the study. Fourth, although the Beers criteria have bccn widely used to identify potentially inappropriate medications to use in the elderly, the data linking use o f these medications to p o o r e r health o u t c o m e s is limited, ll Examining this hnk was beyond the scope o f this study. However, longitudinal studies arc clearly nccdcd to clarify the relationship between use o f Beers drugs and subsequent changes in health status. Fifth, in hnc with the Andersen-Newman model, wc conceptualized insurance status as an enabling variable and expected people with insurance that covered prescription medications to use more medications. However, a direct measure o f prescription drug coverage was not available. Instead, our insurance variable distinguished between people covered only by Medicare (which did not cover prescription medications at the tlmc the study was conducted) and people with other forms o f health insurance. Wc assumed that people with other forms o f insurance would bc more hkcly than those with only Medicare to have coverage for prescription medications. However, many health insurance plans lack prescription coverage and the generosity o f coverage can also affect medication utilization. 41 Therefore, a direct measure o f prescription drug coverage would have bccn desirable. Sixth, only 2 enabling factors wcrc assessed in this study. Future research should include other potential enabling factors hypothesized in the AndersenNewman model s u c h as income and access to care. Finally, data for this study wcrc collected before the pubhcatlon o f the 2003 revision o f the Beers criteria. Therefore, our findings regarding inappropriate drug use during the years 2002 t o 2004 may overestimate the current prevalence o f inappropriate drug use. For example, the use o f long half-hfc NSAIDs, one o f the most commonly used medication classes identified, was added to the Beers criteria in the 2003 revision. It is possible that use o f these medications has dcchncd since pubhcatlon o f the revised criteria in 2003. The findings from this study add to the growing body o f htcraturc indicating that potentially inappropriate drug use among older adults remains a ma3or pubhc health concern. As the population continues to age, 1 the

The American Journal of Geriatric Pharmacotherapy

problcm o f potcntlally inappropriate drug use seems likely to grow, unless effective interventions to improve prescribing practices can bc found. Clearly, raising awareness o f the issue alone is not sufficient and previous intervention efforts targeting physician prescribing practices in isolation have bccn disappointing. 42 As in other areas o f scientific inquiry, understanding the nature o f a problem greatly faclhtatcs search for a solution. By placing the problem o f potentially inappropriate drug use into the context o f a strong theoretical foundation supported by research spanning >30 years, it is our hope that findings from this study will advance our understanding o f the nature o f this problem and that, by so doing, future patients can bc assured that the medications prescribed for them arc safe, effective, and appropriate for their unique health circumstances. CONCLUSION

As suggested by the Andersen-Newman modcl, the risk o f potentially inappropriate drug use is highest among those with the greatest medication needs, as evidenced by poorer health status in this sample o f rural communlty-dwelhng older patients. ACKNOWLEDGMENTS

This research was supported in part by National Institute o f Mental Health Grant R 0 I M H 6 4 0 3 4 - 0 2 awarded to Dr. DeVellls, and by Centers for Disease Control and Prevention/Association o f Schools o f Pubhc Health grant S043 and National Institute o f Arthritis and Musculoskeletal and Skin Diseases Multipurpose Arthritis and Musculoskclctal Disease Center grant 5-P60-AR30701 awarded to Dr. Jordan. REFERENCES

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A d d r e s s c o r r e s p o n d e n c e t o : Susan J. Blalock, P h D , P h a r m a c c u t l c a l P o h c y and Evaluatlvc Sciences, S c h o o l o f Pharmacy, C B # 7 3 6 0 , University o f N o r t h C a r o l i n a at C h a p c l Hill, C h a p c l Hill, N C 2 7 5 9 9 - 7 3 6 0 . E-mail: [email protected]

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