Longitudinal Association Between Self-rated Health and Timed Gait Among Older Persons

Transcription

1 Mrtinez, D.J., Ksl, S.V., Gill, T.M., & Brry, L.C. (2009). Longituinl ssocition between sel-rte helth n time git mong oler persons. Journl o Gerontology: Socil Sciences, /geronb/gbp115 Brie Report Longituinl Assocition Between Sel-rte Helth n Time Git Among Oler Persons Dine J. Mrtinez,1 Stnislv V. Ksl,2 Thoms M. Gill,3 n Lis C. Brry3 1 Center or Stte Helth Policy, Rutgers University, New Brunswick, New Jersey. 2 Deprtment o Epiemiology n Public Helth n 3 Deprtment o Internl Meicine, Yle University School o Meicine, New Hven, Connecticut. Objective. We evlute the longituinl ssocition between sel-rte helth (SRH) n time git, n inictor o lower extremity ysunction, in community-bse smple o oler persons. Methos. Prticipnts (N = 754) were evlute t 18-month intervls or 72 months. SRH ws ctegorize s Excellent/Very Goo/Goo n Fir/Poor. Prticipnts were ske to wlk 10-oot course s st s it eels se n comortble, turn roun, n wlk bck, with time git eine s norml ( 10 s) or slow (>10 s). Generlize multinomil logit moels, juste or emogrphic etures, biomeicl n psychosocil ctors, n ctivities o ily living, evlute the ssocition between SRH n the likelihoo o 6 possible trnsitions (rom norml or slow time git to norml time git, slow time git, or eth) over time. We lso rn repete mesures liner mixe moel with chnge in time git s the outcome. Results. Compre with prticipnts reporting Excellent/Very Goo/Goo SRH, those reporting Fir/Poor SRH were more likely to trnsition rom norml to slow time git or to eth. SRH ws not ssocite with trnsitions rom slow time git to norml time git or to eth. In ition, time to complete the git tsk increse (i.e., slowe) over time mong prticipnts reporting Fir/Poor SRH compre with those reporting Excellent/Very Goo/Goo SRH. Discussion. Among oler persons, SRH is ssocite with the evelopment o lower extremity ysunction but not with recovery rom lower extremity ysunction. This reltionship my inicte n intermeite step in the pthwy rom SRH to mortlity. Key Wors: Git Longituinl stuy Objective mesures Oler people Sel-rte helth. T HE ssocition between sel-rte helth (SRH), perception o one s own helth sttus, n mortlity hs been irmly estblishe, even ter controlling or n rry o helth inictors, incluing comorbiity n cognitive unction ( DeSlvo, Bloser, Reynols, He, & Munter, 2006 ; Iler & Benymini, 1997 ). Furthermore, s SRH is ynmic construct ( Iler & Benymini, 1997 ), ecline in SRH over time is more highly ssocite with mortlity risk thn is single sel-rting o helth ( Ferrro & Kelley-Moore, 2001 ; Lyyr, Leskinen, Jylh, & Heikkinen, 2009 ). Despite substntil reserch evluting the reltionship between SRH n mortlity, however, potentil mechnisms inluencing the ssocition between SRH, or ecline in SRH, n mortlity remin poorly eine. Becuse unctionl ecline is ssocite with mortlity in oler persons ( Ponzetto et l., 2003 ), the reltionship between SRH n unctionl sttus my be inictive o n nteceent pthwy to mortlity in this popultion. Positive rtings o SRH hve been oun to be protective o ecline in selreporte unctionl bility over time, even ter justing or bseline unctionl sttus ( Iler, Russell, & Dvis, 2000 ). Thus, mintennce o unctioning my operte s the intermeite step in the well-estblishe ssocition between SRH n mortlity. Use o sel-reporte ssessments o unctionl sttus in these stuies, however, oes not ress whether worse rtings o SRH re inepenently ssocite with objective mesures o lower extremity ysunction. Lower extremity ysunction my represent n erly stge in the isblement process tht precees isbility in bsic ctivities o ily living (ADLs; Gurlnik, Ferrucci, Simonsick, Slive, & Wllce, 1995 ; Verbrugge & Jette, 1994 ) n is ssocite with increse mortlity risk in oler persons ( Gurlnik, Ferrucci, Blour, Volpto, & Di Iorio, 2001 ). Consequently, it is plusible tht n ssocition between SRH n lower extremity ysunction my be inictive o pthwy tht precees lter isbility n mortlity mong oler persons. Slow time git, n objective mesure o lower extremity ysunction, is strong preictor o onset o isbility in bsic ADLs ( Oner et l., 2005 ). Furthermore, stuies hve reporte n ssocition between time git n subsequent SRH ( Jylh, Gurlnik, Blour, & Frie, 2001 ; Leinonen, Heikkinen, & Jylh, 2002 ). To te, however, no longituinl stuy hs evlute the ssocition between SRH n chnge in time git in oler persons. The Author Publishe by Oxor University Press on behl o The Gerontologicl Society o Americ. 1 All rights reserve. For permissions, plese e-mil: journls.permissions@oxorjournls.org. Receive My 18, 2009 ; Accepte October 28, 2009 Decision Eitor: Kenneth F. Ferrro, PhD

2 2 MARTINEZ ET AL. We sought to etermine the longituinl ssocition between SRH n time git mong oler persons. To chieve our objective, we evlute () possible trnsitions mong three sttes norml time git, slow time git, n eth, n (b) chnge in time git, t 18-month intervls or 6 yers, mong lrge community-bse cohort o oler persons. Methos Stuy Popultion Prticipnts inclue 754 community-living persons ge 70 yers n oler enrolle in the Precipitting Events Project (PEP; Gill, Desi, Ghbuer, Holor, & Willims, 2001 ). Potentil prticipnts were ientiie rom list o 3,157 ge-eligible members o lrge helth pln in New Hven, CT. Pln members were eligible i they were community living, English speking, n nonisble (requiring no personl ssistnce) in our key ADLs: bthing, wlking, ressing, n trnserring rom chir. Exclusion criteri inclue terminl illness with lie expectncy less thn 12 months, plns to move out o the New Hven re uring the next 12 months, n signiicnt cognitive impirment with no vilble proxy. In ition, persons who require more thn 10 s to wlk bck-n-orth over 10-oot course t rpi pce were oversmple to ensure suicient number o prticipnts t increse risk or ADL isbility. The prticiption rte ws 75.2%. During the 6-yer ollow-up between Mrch 23, 1998, n August 31, 2005, 232 prticipnts ie ter mein o 48 months, 27 roppe out o the stuy ter mein o 24 months, n 18 were exclue becuse they require proxy responent ter mein o 32 months. The Humn Investigtion Committee t the Yle University pprove the stuy. Dt Collection Dt were collecte uring in-home ssessments conucte by trine reserch nurses t bseline n every 18 months or up to 72 months. Demogrphic t inclue ge, sex, rce, totl yers o euction, n whether the prticipnt live lone. Biomeicl ctors inclue meicl comorbiity n cognitive sttus. Psychosocil vribles inclue epressive symptoms, sel-eiccy, socil support, n socil ctivity. Dt were lso collecte on ADLs. Further escription o the mesures use to ssess these vribles is provie in Tble 1. Deths were scertine by review o locl obituries n/or rom n inormnt. Assessment o SRH The inepenent vrible o interest, SRH, ws ssesse t ech o the ive time points (i.e., bseline, 18, 36, 54, n 72 months) by sking the prticipnts, Woul you sy your helth is Excellent, Very Goo, Goo, Fir, or Poor? Chrcteristics Tble 1. Prticipnt Chrcteristics Accoring to Time Git t Bseline Slow time git ( n = 322) Norml time git ( n = 432) p Vlue SRH Excellent/Very Goo/Goo 184 (57.1) 359 (83.1) <.001 Fir/Poor 138 (42.9) 73 (16.9) Demogrphics Age (yers) 80.4 ± ± 4.7 <.001 Femle 227 (70.5) 260 (60.2).003 White rce 283 (87.9) 399 (92.4).04 Euction (yers) 11.6 ± ± 2.8 <.001 Living lone 150 (46.6) 148 (34.3) <.001 Biomeicl Number o chronic 2.2 ± ± 1.1 <.001 conitions b MMSE score c 26.3 ± ± 2.3 <.001 Psychosocil Depressive symptoms 95 (29.5) 61 (14.1) <.001 Sel-eiccy e 25.1 ± ± 5.6 <.001 Socil support 21.9 ± ± Socil ctivityg 7.2 ± ± 2.9 <.001 ADLs ADL scoreh 20.6 ± ± 1.7 <.001 Notes : p Vlues were etermine using SAS sttisticl sotwre, version 9.1. Dt re given s M ± SD unless otherwise inicte. Dt re given s n (%) o prticipnts. SRH = sel-rte helth; ADLs = ctivities o ily living; MMSE = Mini-Mentl Stte Exmintion. Men time git t bseline or those with Fir/Poor SRH ws ± 7.14 s compre with 9.81 ± 5.73 mong those with Excellent/Very Goo/Goo SRH ( p <.001). b Number o chronic conitions ws scertine bse on the presence o nine sel-reporte, physicin-ignose chronic conitions, incluing hypertension, myocril inrction, congestive hert ilure, stroke, ibetes mellitus, rthritis, hip rcture, chronic lung isese, n cncer (other thn minor skin cncer). c Cognitive sttus ws ssesse by the Folstein MMSE, with lower scores inicting worse cognitive sttus (rnge 0 30). Depressive symptoms were etermine by the 11-item version o the Center or Epiemiologic Stuies Depression scle, with score o 16 n more inicting cliniclly signiicnt epression. e Sel-eiccy ws etermine by moiie version o the Flls Ei ccy Scle, with higher scores inicting higher sel-eiccy (rnge 0 40). Socil support ws etermine by the Meicl Outcomes Stuy Socil Support Survey, with higher scores inicting higher sel-eiccy (rnge 0 28). g Socil ctivity levels were etermine by the Estblishe Popultions or Epiemiologic Stuies in the Elerly Socil Activity Instrument, with higher scores inicting higher socil support (rnge 0 20). h Prticipnts were ske i they neee help rom nother person to perorm the ollowing 12 ADLs: bthing, ressing, trnserring, wlking roun house or prtment, eting, grooming, toileting, shopping, housework, mel preprtion, tking meictions, n pying bills. Responses were score s 0 ( nees help/unble to o ), 1 ( no help neee but ii culty ), or 2 ( no help neee, no ii culty ), with n overll ADL scle rnging rom 0 to 24. The ive responses were collpse into ichotomous vrible to orm the ollowing ctegories: Excellent/Very Goo/Goo n Fir/Poor. Assessment o Time Git To ssess time git, prticipnts were ske to wlk 10-oot (3.048-m) course s st s it eels se n comortble, turn roun, n wlk bck. This rpi git tsk

3 SELF-RATED HEALTH AND TIMED GAIT 3 Tble 2. Longituinl Assocition Between Sel-rte Helth n Trnsitions in Time Git Unjuste Ajuste Moel 1 Ajuste Moel 2 Ajuste Moel 3 Trnsitions Os rtio (95% CI) Os rtio b (95% CI) Os rtio c (95% CI) Os rtio,e (95% CI) Norml time git to Norml time git Slow time git 2.22 ( ) 2.00 ( ) 1.78 ( ) 1.63 ( ) Deth 3.18 ( ) 3.19 ( ) 2.44 ( ) 2.22 ( ) Slow time git to g Slow time git Norml time git 0.80 ( ) 0.76 ( ) 0.86 ( ) 1.04 ( ) Deth 1.40 ( ) 1.60 ( ) 1.38 ( ) 1.32 ( ) Notes : Longituinl moels utilize n exchngeble correltion structure n were perorme using SUDAAN survey t nlysis sotwre, version 9.0. CI = conience intervl; MMSE = Mini-Mentl Stte Exmintion. Fir/Poor sel-rte helth compre with Excellent/Very Goo/Goo sel-rte helth (reerent ctegory). b Ajuste or emogrphic chrcteristics (ge, gener, rce, n euction). c Ajuste or emogrphic chrcteristics, number o chronic conitions, MMSE score, n epression. Ajuste or emogrphic chrcteristics, number o chronic conitions, MMSE score, epression, n ctivity o ily living score. e The juste Wl F -test sttistic or the ully juste moel in which norml time git to norml time git is the reerence ctegory is 7.90 (18 ; moel minus intercept), p <.001. The juste Wl F -test sttistic or the ully juste moel in which slow time git to slow time git is the reerence ctegory is 8.47 (18 ; moel minus intercept), p <.001. Moel inclues prticipnts who h norml time git t the beginning o n 18-month intervl, with prticipnts who h norml time git uring the entire intervl (i.e., t two consecutive 18-month time points) serving s the comprison group. g Moel inclues prticipnts who h slow time git t the beginning o n 18-month intervl, with prticipnts who h slow time git uring the entire intervl (i.e., t two consecutive 18-month time points) serving s the comprison group. ws emonstrte to ech prticipnt by nurse interviewer, n the time to complete this tsk (in secons) ws etermine using hnhel stopwtch, with interrter relibility etermine to be.86 by intrclss correltion coeicients. Prticipnts who complete the tsk in more thn 10 s were consiere to hve slow time git, wheres those who complete the tsk in 10 s or less were clssiie s hving norml time git. The 10-s cuto point hs previously ientiie threshol response between time git n the evelopment o isbility in popultion-bse cohort o oler persons ( Gill, Willims, & Tinetti, 1995 ). In ition, chnge in time git uring n 18-month intervl ws clculte s the ierence in time git between the two relevnt time points. A negtive chnge score enote n improvement in time git, wheres positive chnge score enote slowing o time git. Dt on time git were complete or 100% o the prticipnts t bseline n 95.5%, 94.5%, 92.5%, n 90.8% o the noneceents t 18, 36, 54, n 72 months, respectively. Sttisticl Anlysis Cross-sectionl bivrite ssocitions between prticipnts chrcteristics n level o SRH n time git (norml vs. slow) were etermine using c 2 or t -test sttistics t ech o the ive time points (i.e., bseline, 18, 36, 54, n 72 months). To ssess the ssocitions between SRH n the likelihoo o the six possible trnsitions over time, we use repete mesures generlize multinomil logit moels run using generlize estimting equtions. The mgnitue o ssocition ws enote by os rtios (ORs). In ition, we rn repete mesures liner mixe moel with chnge in time git s the outcome. Potentil covrites were selecte rom n priori list o vribles previously etermine in the literture to be ssocite with SRH or time git. Covrites were selecte or inclusion in the moels i they were ssocite with both SRH n time git (norml vs. slow) in bivrite nlyses t the p <.10 level. The moels were sequentilly juste or emogrphic chrcteristics; then or emogrphic chrcteristics n the number o chronic conitions, Mini-Mentl Stte Exmintion (MMSE) score, n epression; n inlly or ech o the orementione ctors n ADL score. All sttisticl tests were two-tile, n p <.05 ws consiere sttisticlly signiicnt. Results At bseline, 543 (72.0%) o the prticipnts reporte Excellent/Very Goo/Goo SRH n 211 (28.0%) reporte Fir/Poor SRH. Slow time git ws ocumente in 322 (42.7%) o the prticipnts. Tble 1 presents the prticipnt chrcteristics ccoring to time git (slow vs. norml) t bseline. Compre with those with norml time git t bseline, those with slow time git were more likely to report Fir/Poor SRH, to be emles n non-white, to live lone, n to be epresse. They were lso oler; h ewer yers o euction; h more chronic conitions; n h lower MMSE, sel-eiccy, socil support, socil ctivity, n ADL scores. Comprble ierences were observe t ech o the our ollow-up time points (t not shown). Tble 2 provies the results rom the longituinl moels evluting the ssocition between SRH n trnsitions in time git. In the unjuste nlysis, the likelihoo o

4 4 MARTINEZ ET AL. trnsitioning rom norml to slow time git ws increse more thn twool or prticipnts hving Fir/Poor SRH compre with those hving Excellent/Very Goo/Goo SRH, wheres the likelihoo o trnsitioning rom norml time git to eth ws increse more thn threeol. The ition o emogrphic chrcteristics to the moel (Ajuste Moel 1) reuce the OR or the trnsition rom norml to slow time git by pproximtely 10%. Further justment or the biomeicl vribles n epressive symptoms ttenute the ORs or the trnsition rom norml to slow time git by bout 11% n ttenute the ORs or the trnsition rom norml time git to eth by bout 24% (Ajuste Moel 2). The ition o ADL score to the moel urther ttenute the ORs, n prticipnts who reporte hving Fir/Poor SRH h higher likelihoo o trnsitioning rom norml to slow time git (OR 1.63, 95% conience intervl [CI] ) n eth (OR 2.22, 95% CI ) compre with those reporting Excellent/Very Goo/Goo SRH (Ajuste Moel 3). In contrst, Fir/Poor SRH ws not ssocite with the trnsition rom slow to norml time git or rom slow time git to eth in either the unjuste or the juste moels, with the exception o the moel justing or emogrphic chrcteristics only. The ully juste results rom the repete mesures liner mixe moel inicte tht time to complete the git tsk increse (i.e., slowe) over time mong prticipnts reporting Fir/Poor SRH compre with those reporting Excellent/Very Goo/Goo SRH ( b = 2.97; p =.02; Akike s inormtion criterion = 16,091.8 bse on n utoregressive heterogeneous correltion structure). Discussion This prospective stuy provie the opportunity to evlute the longituinl reltionship between SRH n chnge in time git, n objective mesure o lower extremity ysunction, mong lrge community-bse smple o oler persons. We oun tht the likelihoo o trnsitioning rom norml to slow time git, n to eth, ws higher mong prticipnts reporting low SRH (i.e., Fir/Poor SRH) compre with those reporting Excellent/Very Goo/Goo SRH. These inings remine signiicnt even ter justing or emogrphic chrcteristics, biomeicl n psychosocil ctors, n ADLs. We lso oun tht time to complete the git tsk slowe over time mong prticipnts reporting low SRH compre with those reporting Excellent/Very Goo/ Goo SRH. Together, these results support the supposition tht the pthwy rom SRH to mortlity my inclue n intermeite step tht precees isbility. SRH ws not signiicntly ssocite with improvement rom slow to norml time git. Prior reserch suggests tht n ssocition between SRH n unctionl sttus serves s n intermeite step in the well-estblishe reltionship between SRH n eth ( Iler & Ksl, 1995 ; Iler et l., 2000 ). Although these stuies re vluble in moving beyon the generl pprecition o the ssocition between SRH n mortlity, they o not iscriminte between omins o unctioning. Rther, our inings show tht SRH is ssocite with lower extremity ysunction, type o ysunction tht my represent n erly stge in the isblement process preceing overll loss o inepenence ( Gurlnik et l., 1995 ; Verbrugge & Jette, 1994 ). Consequently, our inings suggest nother potentil step in the pthwy between SRH n mortlity, with low SRH ssocite with lower extremity ysunction, which increses the risk or ADL isbility, which, in turn, my le to eth. Furthermore, we oun tht Fir/Poor SRH ws ssocite with n increse likelihoo o trnsitioning rom norml time git to eth. These results suggest tht SRH is ssocite with mortlity irectly, s well s inirectly through its reltionship with the evelopment o lower extremity ysunction. We oun, however, tht SRH ws not ssocite with improvement rom slow to norml time git. This ining is consistent with prior reserch tht hs oun tht poor SRH is ssocite with ecline in unctionl sttus but not with recovery o unctioning ( Iler & Ksl, 1995 ). However, the reson or this ining is uncertin. Prior reserch inictes tht oler persons my ttribute ecresing physicl cpbilities, such s lower extremity ysunction, to ol ge s coping mechnism when ce with wht they consier to be intrctble unctionl ecline ( Srkisin, Liu, Ensru, Stone, & Mngione, 2001 ). They then my rte their helth more positively s result o reucing their stnrs o goo helth. Prticipnts with slow time git who reporte positive rtings o helth my still hve been ble to conuct their ADLs, yet my not hve regine norml time git over time, thereby contributing to the lck o n ssocition between SRH n improvement in time git. Nor i we in tht SRH ws ssocite with the trnsition rom slow time git to eth. Despite the strong ssocition between Fir/Poor SRH n subsequent mortlity (DeSlvo et l., 2006; Iler & Benymini, 1997 ), our inings suggest tht once lower extremity ysunction is present, Fir/Poor SRH is not ssocite with progression towr eth. Aitionl reserch is neee to etermine the mechnism(s) responsible or the ssocition between low SRH n mortlity in the setting o norml, but not slow, time git. Our use o repete mesures o SRH n time git is signiicnt strength. Prior stuies evluting the ssocition between SRH n unctionl sttus hve inclue only single bseline ssessment o SRH ( Iler & Ksl, 1995 ) or ssesse chnge in unctionl sttus bse on only single ollow-up ssessment ( Iler et l., 2000 ). Furthermore, in contrst to prior stuies ( Iler & Ksl, 1995 ; Iler et l., 2000 ), we evlute n objective, perormnce-bse mesure o unctionl sttus rther thn sel-reporte mesure. Perormnce-bse unctionl ssessments re less sensitive

5 SELF-RATED HEALTH AND TIMED GAIT 5 to potentil conouning eects o ctors such s seleiccy n epressive symptoms thn re sel-reporte ssessments. In ition, unlike prior stuies, our inings rw ttention to slow time git s potentil precursor to ADL isbilities. Becuse time git is incresingly recognize s geritric vitl sign, n ssessments o time git re esily ministere n reltively strightorwr to interpret ( Hry, Perer, Roumni, Chnler, & Stuenski, 2007 ), our inings lso encourge uture reserch tht utilizes time git to unerstn the mechnisms tht relte low SRH to mortlity. Although ichotomizing time git might be consiere limittion, our results i not chnge pprecibly when we nlyze time git s continuous mesure. Becuse the PEP cohort comprise members o one helth pln in smll urbn re, the generlizbility o our results my be questione. In summry, the longituinl ssocition between SRH n chnges in time git my serve s n intermeite step in the pthwy rom SRH to mortlity tht precees lter isbility. Ultimtely, ientiying persons with lower rtings o SRH my help clinicins ppropritely trget oler persons who woul beneit most rom interventions to reuce the likelihoo o eveloping lower extremity physicl ysunction n potentilly ely onset o ADL isbility n mortlity. Future reserch shoul ocus on ormlly evluting lower extremity ysunction s meitor o the reltionship between SRH n mortlity so tht the mechnisms riving this reltionship cn be more ully elucite. Funing This stuy ws supporte by Grnts R37AG17560, R01AG022993, n K01AG rom the Ntionl Institute on Aging. The stuy ws conucte t the Yle Clue D. Pepper Oler Americns Inepenence Center (Grnt P30AG21342 ). Dr. L.C.B. is 2007 Brookle Leership in Aging Fellow. Dr. T.M.G. is the recipient o Micreer Investigtor Awr ( K24AG ) in Ptient-Oriente Reserch rom the Ntionl Institute on Aging. Acknowlegments We wish to thnk Denise Shepr, BSN, MBA, Anre Benjmin, BSN, Pul Clrk, RN, Mrth Orvetz, RN, Shirley Hnnn, RN, Brbr Foster, n Alice Vn Wie who ssiste with t collection; Evelyne Ghbuer, MD, MPH, who provie t mngement n progrmming; Wn Crr n Gerline Hwthorne who ssiste with t entry n mngement; Peter Chrpentier, MPH, who evelope the prticipnt trcking system; n Jonne McGloin, MDiv, MBA, who provie leership n vice s the project irector. D.J.M. perorme the t nlysis, wrote the irst rt o the rticle, n contribute to revising the rticle. S.V.K. supervise the conceptuliztion o the issues resse in the rticle n contribute to rticle writing n its revision. T.M.G. helpe pln the stuy, incluing instrumenttion, n revise the rticle. L.C.B. supervise the t nlysis n contribute to rticle writing n its revision. Corresponence Aress corresponence to Lis C. 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