A comparison of the SF-6D and EQ-5D - University of York

19 Pages·2006·0.19 MB·English

Work in proysess please du no cite or cies

Section 12 Eneraduetion

TN oetuuliyanalyais, a profewnce hised mesure 0. Health is seeuuted +0 conduct

scovomie appraisals uf compating heal cere antervemtinns fron a soisty-side

parepectye Tasever, th

xe several instruments avatlable ro evearchors sorkirg

tus this arsa, ach bas strong theoretical Tuundativns, ara di:ter in thear healin
Llasificaton systems. ccthod af elsiing preferences and sepriny,fumetions. Stadnes
that hove compared their prapertos hase found thal he mesmutes are all vedi and

viable ia uber esen way (Macran ct al 2003) bot milriss for weal Real slates ere

sam vary druamaticully (Repee & Wiisox 2002)

Twp eoaengnly ised enorsares of qualcy of lis are the Kurngol KOSD srl rhe SP36

‘The Suragal is single ts se an ean tee Ta

Uifstences in health (Doli ct

1995, Beactor et al 1889) However, it bss been entered for tving poor sonsitiviy

ni nexoscients im vonditions assaeleted with a morbidity (Brazier st al 2002) sad

Fo ain male‘ letecrsrnall changes in het Fis sier st xl 1999}, The SER6 6 4

very wide’y used gonovie memurs of HRQoT, bul 4s ant designall for sconomie

staluasion sings i docs ret ces ieit y inearperttc prefereness into ils senting

algonittne A prsforence-based messure of health (SE6D) has seccutly bees decived!
Fionn the SIS6, [© has a Tange eese:ivive system andi :6 claimed te have a wseter
degree 1 ventvity ez o be les skewed than the FQSD, Hesvever early studies

‘av ideutiied ¢ nunnbsr at concerns (Long

anh 2003. O'Brien 2003). The mridel is

Jost tu vernrabel the

sue of the pore

hevth states (Rracier 2062) ancl ray
rot be seme tive 49 Caenges in esnditions of high munhidity (Longwertks, here is

also eoneers aves whether the SFED has vompramlsed t

esotipive tichuess and

seesiiviy of the STE esier 2003} aul whether he ussumprions af muliatetbite

tidy theory, on which prefscenve:aased messes of healh are Kawnded, can be

applied this measure (O"Dien 2005),

This poaer investi

wheter spike content ea comm.ity-besed population al
pets reco.¥139 physiotherapy istecvenLoes fet nech pin, the choice wl rstrurent
nay Cage Uke results wr eonclasions of an eexmnes: eveletion, ‘Lhe dtaset n the

SPRINTER tial included HQ-81 smd SUG a5 cutcente raeasurss, “The aims ot tis

Davul Leste Presented wt TSG July 2003 Page 2
‘Work in prayrene - plage do nor cite or crc

ppuper ure uo shi low the estimates wPQAL Ys and cost-ullty can change depending
cor the choice uf ausceme meaenre, “Lhe aaper then “ooks whether such dliTecences

can be ascribed to the ability of the Teal sue desorpuive systems 10 detect

enn iTevences i srw for smile healthstatss

Ih er trom the wal

being aittareee

Section 2: Properties of Kareqol EQSD and Shurt-Furm 6D health state

classification spntenns und inde measures

he SHAD pweforanar hese neem 9” hell iy der'ved from the SEBS Ny 2 to

stage process

First, lever questions are taken fiemr the SE36 Wo define the sis dimensions of tae

eh

SPOL> (Hysieal funstionmg, vols linwation, sovial fimetioning, yin y ments ho
and vitality, Each cimonsion bas between four and six levels allyeing, 1806
(ox4aSnfx eS) health states to be usa. The procedure 10 map the SI36 10 the six
dimensions quite corsp'ex and ‘s dlescrined 74 Agpendix 1, The esimetiun of the
‘SoD a1 rsod 2 Lacaradlitve uty medel, This .maoses the asssrnpciun bet theee
is so interactor fir pefererves urame the ltribules ut all, Tor sxuraple, 2 chasge
thom Jevel 1 te level 2 on tke pain dicsensiun would reduce overalls iily hy 0,082,
asganlless of the levels on the ther dimessions, Unis in tum requires thal the
questions ne in the survey ure phrased in such a say ase avoid inleraesons
terween chmongioxs. Fer example, questions shoulé not ask shout huw pin has

aAtccted physical functiousrg. A closely rolared assumption is structural

thal w olether is conceive fn un inisidual Feta at any

sl on thal altribul

regardless of the levels on he otisr eeibutes, so ther ell

‘combinations othe levels in tbe syste: sre possible

The secoud

It apply Ge preterene till) The bari ens estimated using He
scandard! gamble wetbod to obtain uta values thu 835 eespundemts hum dhe UK,
sEeneral pablic, 248 out of the possible 18000 heel stale were chosen ka he valued

A total oF vie stony por subyect wero valued

ve to an upper se-chor of ne

ddystimetion (evel 1 om all dinnsinnsy ena liver anchor of the west eels fe all

Dasid Epsten Prosemed at (1486; ly 2003 Page t
‘Work in progress: ease donot cite or eteulats

eesions ‘The lower anchor sas ther valued relative «© ll health" ancl death
The socond lonery valuyy wore sei be normasise he Fist Lodery vates co the
vomventions] 10,1) seals of death to Ful hoalth, A tmcar axkitivewilty erode eas
by ordinary least scueres using Ge mes valuation of the dealt states 96 the
ependest salable and with 25 SEOD item-‘cwls and 1 dummy variuble iedieating,
‘whether une oF mare itoms seas "severe! ac cosadates, The mwist severe SEGL state is

veyed 1 0.291 Brcvier et al (2002

pint that negative absecvacins, which
vpracenl sites selued at verse than Gualh, dsl exue i 7% of sseevations fu the

valuation survey bul the model ovee-predicted tbe velue of the poones:healta states

Ue alittle fon Toh racer

‘The FOSD iv u-mch simple: heh stu classical then the SPRT Recs

‘he tive dimensions (mobil, solf care, usual activity, pals and depressions is

ascised by 90

auescion, with ono of Unee passible responses, The insleumeat
and és tari wen in Apendin 2. The Leif? ws entimuled using the Hinge trad
cll usetheu Han & sample oF 3995 respendtents of the EK general papain, A

Finoer aci’ve misty meade sas estraal gt the ividoal level sing gensrs ised

using the item aevels anal a term shih Identified whether any
mension was alls renet severe level as covarittes, The mas! severe FQST ste is

value at 0.594,

The SPRINTER trial dataset
The SPRINTER trial was designed to compere Ihe sosteffectiveness of a brief
‘ngersomtion BL for physiotherapy rh

J physiotherapy (CC tor patients in &
conumunity s€sieg with nes pane, 129 particysania vere renskmived 9 Tame) 129
to LC. ations wane assed 1a vomplete the FQSD. S16 and use of heekthoate

resource guesLomnames at bese,

unin und wglve wis poste

Davi Fpstein Presented al TSC

uly 2008 Peget
‘Work in pregrene please de nor eite or elroulere

Section 22 Methorte
OAL Ys were oonstiscted then wilty seams by the “ares under the curva? meth

AMirthess otal 189M, eecemental mean costs, QALY'S and the incremental cos

siveness ratio wet the ebice ot insuueent

ealoulaced Uc investigate whet
alfested the estimate ot cost effectveness berseen the wy interventins thased em

sts values)

The LQSD and $#6L instrmments are designs 1e measure ARQoT. or the seme see,
with sero representing death snd onc sepreseanng ful, bealte, Negative values
indicate sires velued by the veneral popula a worse um aleath. is nepertert
fer che purposes of economies evaluation Mat if thers are twa posible instrument “or
snsersing heallb-e.ated miliny, tien a pacticular valne gevetered by one ‘nsteument
shoul Suave um identi snrenpretation om the ater insirument, That i, the index
values: generated by the 69 instaneats sho.id bots ve Well coveted anal

i. Ter See why they must agiee, caster @ Wypetbetieal siwation in whick

home ate rms reatmenss & and B Wet gan he give

by severely il petiomt, and
horse of wo inzamments LEQSD and SFODI with a high degree oF ceurtarion, whore
one Indes cen I rapped the other by 2 ennai bunslenenation, 174 patent

fon 8. thei: coriion uses nochange over the fie hurizam of the alesis, TT

Ihey ere gicon #, they die immediatly for some reason Futility $s messed using
the SHOLY anstrumtear, the paticets unbity is posite acu tke pater scosives positwe

QAT Yin irowtment A an

ony in B. Mf orily is mensred usiry tks

‘QSL, wing is

agative and so the pationt ecowos negat

2 QALYs in acatment A and 20:0 in B.
neretare i cost

re the same tn A aed B, usue SEED will vou A aed using

EQSD wi Koso B, Therefore the chuive of resent sil by

iter depending
only om tks measure of uibiy chosen, ‘This porsonge result will away be possible a

ote Ba cbovee oF uty measine where vals “or ume 2am be npr

suler 4 non-identical bot posinve tinear cansZarmation, Thetetore al ae 189

measures generate 3

cioally Uilevent salty values Gr the sae

samme pont in thie, hen the iaruments exenal ‘oe moascring fhe same thing hs

Tesel no xgreement and correlriun was visually as

sod using a searesplot
Longmont 200, O°Feisn

Byvid bccn Presented ax TESG luly 2002 Page §
Work Sn pruyrens place de no cite er cveulate

“The seussity ofthe unsteument to measure stianges in the health of

Lime hs two veparete gspvets, Flitly, he inssamceer must accurately

health state of wach incision, and allows she

er] eulth ntute Le change in

the lif unt accurately estimate

resqnse bathe inal actual heulh, Sous

sscetis proitronees orth eqs co that heath sts

‘wen tespeet co the ati.ity of the instoument to wecurtely recor sae insides
state, Lomgisonth (2007) and Travian (1998) sxusider Boor and ceiling slicets.
selling sifec: ecears when 2 populacion gives a high proportion of scores for some
dimension at he Least severe Level. and if presezt will make the instourne=: insensitive
ve further irxgnnectments in health for he pupulation. A Toor effect occurs edit the
popultion ineler corsideratign givas a high praporvinn of thse resporses ul ths Lowsst
local for one or iors diemsiges of a. inetrment. IP this the eas, th inarupnent

‘wall hs iescasttive vo further decrements inthe healt ot this sepulaten,

Floor sre! evilny, fees ste estimated fir tho SPRINTER population by calling,
the proportan at responses atthe worst aun best possible Jevel for each dimersion af

instcumeu., Other eutboss scom: te have declared 4 ceiling ot Hoar effect when

tive then BO 0 responses ane al the highest or losses! Revel

The construct eat of ths preferesoe-b

od andes can be asnessed by usvestigsting

veh iL Sore

25 with 3 knawn ar hypochesisel mess of heh, Tresiar ot

199%) compared the exp

ed Uistubution of total seores with a clagnosis of ehiorae
iysical penblens. but this is col availuhls i: the SPRINTER dataset, The STA

enters at question om se’ awessed heclh. which fae five possthhe responses

sng fron “eveslent Spoor", A eeu nesessment a eatnnct valely gam be

made by cornaaring selt-assessed health with the SF6D.ge.. thougiy loage sige, Cut
sel assessed how'sh need ret necesserily worse with preferences fer health from a
snore perspective.

Ths association elaveon sell assess! oul and “he preferenes wulue gonsrated by

sash instrument is assented using “box plans’, tacse goaphis ate able co carelscly

suimaranise anc compare dhe distri

David Epstein Prose at Hes8C Fly 2093, Page 6
‘Wock in progress plswse do mot sit or eielate

A fimher asseesmen. pf xersiivity can be made hy exaurimary che Freyuency sith

which individuals change thei repoted EQSD 9: SEUL stats over time, gheon hal

hey report an dmnprovernene self assessed health over Ihe sence petiud A Tea
proportion of patignrs cepesting an unchanged EQSD health sta: hut imaprived self
vasesined hovth between these periods would indicate a Lack of sensitivity in the

‘nacre,

To test this espeet of sersitivity of he TQSD. the most ireueraly used CSD heat th

states reported at evelve monbs postrendamisarion we

compated ‘sith the stete

repr bassline fer dhe FQST) instrument hy each ialividua There are too meny

states repartod using the SEGD to mie this lst test practical forthe S6Dinskeumemt

The deg af buh irstrurcents assures 2 Finear aldiive model, ann ere‘ime

inkopomlence: betwee

vill atthe, Tis dsterinine whether a Finer eel is

appropriate, wo compute & eome'ation matrix bergen the questions used in the

inscrament for bath EQSD and SEGD (*BLien 20031

Section ds Revabts
Table | sss summery satistes forthe tec msssures et baseline an! mem 12 ‘The

mae eels of the

SD ay is proatr than the EQSDuas at bath follow-ups, wath a

lower variance anil a smaller rings. £083 of the sample repented « gene-al

limpeevomene it seltessessed best ever 12 months, 13 24 reponed « deteoeaion

ars] 27% reporto na change, Srsilr emi were

rv shen mnalysed hy treatment

gop. The mean chings in ulilty ocor 12 months mexsurel using thy EQSD yaa is a

etecse of (.0U2, and an inet

oC DADS using the SEM ge. Table 2 shows the

‘ashelTecr'veness ofthe irtorversions hase ora a

is of expected values. Usual
cor js roe sapensive tan BIL Using the BQSD. as , CC is slightly moe affective

sand las an ICER of £18709, Una the SH6D,

«is sighrly swore effoctive and

doztinates bused or expected values

| shows the distribotion of each measuee at baseline

ver sreasure appears

we comeleted with selt;assensed 1

th althagh the -elitively small eumber et

Dsl psi: Dreseared a MIPSC Luly 2003 Page F
‘ork in progress ploave dont cite oF cltculats

scores Hot Uhe EQSDinis Below 0.8 appear co be asscciane with Lower Levels of wel
~ssegsed health

‘or cach patient at

fe 2 ahs a seatterplot of che BQSDyie, atl SEODA..
bagele and 12 anonths post eamlamisation, ‘The EQSD qa) 1M SPD, re wall.
tormelated wth ecch one, bu: they cannot be sald to agree fhe tel vabnos do mat

orci wilh the 48° Tine), ess une: 4 of the uty scores estimated using the

FOQaDgie ume neyal've. None ofthe SPAM pas are neyal've since the salue of she

worst possible stats using the cai is 291 Thore ars clamr gaps in the rumor Tine

wwller no scores possible using the EQSD wi

Table 3 shwws that the KOSI) may hase # ceiling effect for “he mmtiligy an sof ears

-menssons wita this popnlstion, and no fear effeer There a a celling cost for tke
‘Role hnitetion' dimensiox othe S¥6D, .‘Thase is no evidenve ua tlooe eestor
my of the SESD dimensions. Fxaminstign af the esponses for indv-cul clemen's of

the SFAu shows u high prozomtion of parrecipants reported cithsr ‘no prob

cbslity un athe aml dress! (Quention SIS}. or “Tinted Yok in vigamous asivty"
{Question SE3a} or both bu this dovs not rinslace use citer 4 oor or eciling eMet

Tor the phisceal functioning dlasion asa schol

Tah

shows ebanges in heal slate micasurs! will The FQST) intrurnunl Bel

hoeseine and mms 12, Bight heel -h scan were wad by 822A ef rexuonlents al reonth

12. Relatwely few S449 particapanes reponed the same health stte 49 both tlless-

ps saroeys,

Correlacions bona the answers to the SEGD saxvey Roem ate ler

fount abe U4

Tevel Gu ali elamenis except “ability to hee ami dress cmesell ys “severity oF

Aleprossion’, and ‘ability to hath anal dkess oneself ws Svitality’, Corelatioa
coctficionts between the dimorsious of the EQSD surves were significcen for ll

fexcemt the pure” dimension,

Section §: Diseassion

‘The SFED 4, ood EQSDigae both ira ty mcasare proforonce values for health on 3

scale where sera wypresemty dosth gel one sspresenss fill sath “Theret

David Epstein Pr

red at TICSG July 2008 Page 8
Work in progress ple

do sot eve or viet

sho.ed be measuring the sare rng, and tke choice of esstumon shoul wl

inflaewe the eorchisions of #9 ecorsmic evaluation. ‘This paper has shown that,

shen epplici in he SPRINTER lal populatiot, ther usual care is vostelfetive

hy meximum willingness i» pay is gestae ths: £19000 when asin, The ROBO

instrument hua bot intervention dominates won vsing the SFAD instrument

One reesem explirsd in the Fuealune fur the lack oF agreemeatt botwsan che 10
vecesuies if that che EQS is uot sonarive te changes 2% he upper end a the

Alistibur‘n, af wal aid the SSD is zt

sitive ta changes at the lesser end,
Longworth ot al, laoking st patients

ving liver Inesplants, eve nted «Toor

a far the role Fins dimension af SFGD with 42

‘al patieres reaosang the

teost severe love’. They found am ahsenes af Ahi elleel lr wny dimension: if the

TEQSD. Bisaer e191 (19982, noking aLa_ population copresearatively deme fiom GP

practice lists, und a ce.ling eflect For the older version af dee EQSD across all
snensions, Che Fralingy fn his study ol patients receiving plysiotherapy le

rock pain ky nt, ialiate my evidence wf Muar effets ta eier neue fev is

ppapulisinn, swt dy mutiosts ceiling effeet far the KOS robiling und se cure, und

forthe vole limiation dimension of the SHOL.

This study aes co widens that the ruts Tinjiativn dimersion of the SEBD is

<ptible to & floor enact wh

n the population of pacts 4s Fairy il or a ceiling
elect whan Cie pooulaion has low mocbidity. Our study, buweves, shows shat the
citing effect is no: bocanse the cussions which make up tis dimension are

Inappropriate, Taen on uheir own, neith

questo: eshibis & oe'ling effet, The

questions ere owe much oF the line ware yon lint inthe kind work er other

envy dee 19 physivsl herlth’ ($Fés) and chew amich of the cme did you

acomplia cess than you wld ihe due to sulfone’ grablores' (SPS), Amuvurs om

range from | (ll of the time) 10 8 crane of the tnses Lf ptisuts da not answer “all of

the time” co bot: questions. they are alloted 70 the Least severe

1 of the role

humetanoe dimension, This ss biahly Hikaly in ¢ community sanple

ec: though

clakvely few patignts acawersad ‘nume of the time w either oF these questions, A

Sinise crguument may eep'vin why Lomyovorth ct» CURIS found a floor elect for his

lanenstom in their solacively I population, The wwe questions are highly some ata

seid theretne aalieetn eho

ited in their cls ull uf the time in paysisad health

David Epstein Prevent sh HSC July 2003 Page 9
Work in progress please do not ete ar sate

rns enw Jee lnited because ot emotional problems These palicns will be allocated,

to che amast covery Iovel of the dimenioe, WL enay be that an altemative methoxd 2

jonstruct the 40'S litauon eimension cmt he dsvived, thst wuld nt pouce suc

severe ees or eeitingeffees

Howerss, he abserae of a flour effect iy mel nevessorly a sength of the EQSD
Ineumess. The phrasing of the mobi: and se care qucatians supgents tha the use

of the rast

state will aly he appuopigte Fox a very small minasiy of severely
ciotbad patients, This hy Leto a high proportion of the EOQST sites being value ak
wane than death by the general populanos. boc they akc velikely fe be useel in

pretive, Since there are relatively Hed

psible healt fates = the LQSD coe
i seh as SPATS und TUT

ralormine he #6 ity of the FQSD to be scusitive fo cherges in HRQhL, Since arly

with other orstrun

ins principle ix may. Father

level T saul level 2 ale avauble in pruclve for malty el care, thes. ay

the prcaence oFsucl a promoumeed ceiling fect,

Troe etal (19935 furl that unt 1D health sates counted for 95% of observations
fn their voramunity-hused populicign, usr, um olde versio 9 the LQSD. Tn this
popu'iting, ght MCSD health states as count fo 82% of those used aver al follow: op
ceriods, However, the feynoncy vath whieh pamicipants aseuster ths same healt
sate in subsequent follos-ups ss very Kw, This inites that patiests ute ube 46
vepisier shanyes in Ther health sate using the TOS),

“The spacing oC the ti values oF the TOSDnsa alum the number lize uneven, th

isnot ponsihle tg oyster an index ee: hyhvout, 0 el 884, neg Rolween W487

and O16, This scuunts for the triamestl, mor-syrencuical distiborion of “he
HOSDqco Seat te Figulo 2. The SFAD overs the number Tine much more evenly

cover its mor fi

4 range ‘here ie no reason sshy'the indioes shoul cover tie

surrber Lint ese, ety that the index shih acunately relleck

preferences. Hiwever i likely that rhe gop inthe number Hiss seen in the EQSD)

incicetea laos of health states forthe ase of pions with bec Health,

This study doas sol prasent usstnguow evidence ether fre ur ayia the wiser

at the FQSD classification sestemt i insensitive kn ehamges in heullh status in x

David Cysein Proserted al BL SC Joly 2003, Page 10
‘Work in progress plone tw cite circulate

community papulalina, in the one hand. patients de: not tend ta reson The same
ul sake at dulexent follow ups, which indicates the instrument is alowung patent
tw rvurd ehanges in he th stats, Ou the oder hand there ane eclstvely few health
seatss avuilshe far palien.s with Peller healt, particulerly m the sel? sons an
rmabilty dirveesions. (io SEOD has more bealth states. Te my be pamsible to
ingpmows the evi elfet ofthe rae Timitarion dimension of the SFD by chmging,
the way the levels of this dimension a

sorstratoa fom th

36 quescians, “The

FOQST snight be inyoved by makicg the lowest Jevels «© the mobility aud self care

dcnensions [ass sere,

Toe index manures of both insumants tend to eoezlate with se-assessod health

hough i is aot pose wo say whether one peefoonns better than the ooher. ‘The SRED

js snewen to over-value poor bealth states, Tes clear Fem the analysis af varrlacinns

(oat there are sippiticent interaction etteets between the questions used to corte
the dimensiuns of the SPAT), and thal the Ticeur ecitive model is rut valid, The
questions of the SEE appear designed 1p encyurage Feractions (lor samp’,
ceuestion & asks “How reel did pa: antertere with your normal seerk eneempassing

pain ond physical lunctierragi. The est'mation of interaciom effects woul secure 3

vac Lager simple sce “ham thal en tn estinn © the censon aed here, The lack of

ortboganality maybe ¥rexson wy the model shows law predliive abil.

The two instruments airs ty messune dhe same thing, thal is, w prelenerehased

fewas.ce of deal, They are elsedy net penerating equivelem values tor peviamts at
the sme pial in tore, This is mit umesnectet! given the eifforences in boab

lvssliewion aysteea ene the estimation of the tsi The

implieution ig thst he
ion about which berth
Snnalogy to adopt, omer that tis chutce & net arbitrary, the analysis plan Fae

ehoies ef instrument is impoctane and oan change the devi

sung sully sherld spuvify which im alsance which instrement isto be used to moasnee
ksnth outcome, and paidasce thor, NICE and other decision makers shoud specily
‘sbich wstrum

ss puelerced

Fram the evi

sented hese, beth

ms couli be improved Py changes in
Geir construction, ‘This would neconitne re-csmation ofthe preference weights. It

is ulso unlikely that the Tinea additive model is stable especialy fer the SPA

David Epstein Presented et He SU July 2003 Page U1