Art 30 Criterii RA

8/4/2019 Art 30 Criterii RA

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C l a s s i f i c a t i o n c r i t e r ia f o r r h e u m a t o i d a r t h r i t i s

A L E X A N D E R J . M A C G R E G O R

T h e n e ed to d ev e lo p a s t an d ar d ized m e th o d o f c a s e r eco g n i ti o n in t h e s tu d yof rheum ato id a r th ri ti s (RA ) has been r eco gn ized s ince the ea r ly 1950s . Theear l ies t app roaches invo lved deve lop ing cons i s ten t methods o f c l in ica lapp ra i sa l based on the op in ion o f the examin ing phys ic ian as to thepre sen ce of d isease (de B16court , 1953; de Graaf , 1959) . A n exa m ple wasthe Manches te r c l in ica l g rad ing sys tem used in popu la t ion s tud ies byKellgren e t a l (1953) .

There were a l so a t tempts to deve lop a more ob jec t ive app roach toc l as s if ic a ti o n . A n ex am p le is M ia l l' s s t u d y o f RA an d p n eu m o co n io s i s ina We lsh m in ing co m m un i ty (Mia l l, 1955). C ases o f RA we re c lass if ied

on the bas i s o f a charac te r i s t i c h i s to ry o f po lyar th r i t i s invo lv ing theper iphera l jo in t s, w he ther res idua l phys ica l s igns w ere p resen t o r absen t ,s u p p o r t ed b ye i t h e r r ad io lo g ical ev id en ce o f RA in t h e h an d s an d f ee t,o rby a pos i t ive d iffere n t ia l agglu t inat ion tes t (Bal l , 1952) . T hes e cr i ter iawere f e l t to p roduce a r ep roduc ib le d iagnos is by on ly inc lud ing cases o fs e v e r e R A .

Oth er inves t iga to r s ex am ined the ab i li ty o f ind iv idua l c l in ica l f ind ingsto d i s t ingu ish RA f rom o ther rheum at ic d i so rder s . Cobb e t a l (1955) , in ap re l iminary ana lys i s o f the P i t t sbu rgh Ar th r i t i s S tudy, r ecogn ized tha tr ad io log ica l changes iden t i f ied on ly a smal l f r ac t ion o f ind iv idua ls w i th

jo in t d i sease and tha t r e la t ive ly minor d i ff e rences in def in i t ions led tola rge d i ff e rence s in the num bers in the popu la t ion tha t cou ld be c lass i f iedas hav ing RA. In th i s ana lys i s , morn ing s t i f fness was no ted to d i ff e ren -t ia t e RA f r o m d eg en e r a t i v e j o in t d i s ea s e. K e l lg ren an d L aw r en ce ( 19 5 6 )s tu d i ed th e r e s u l t s o f s u r v ey s o f r h eu m a t i c co m p la in t s am o n g ad u l tinhab i tan ts o f a sample o f the popu la t ion l iv ing in Le igh , Lancash i r e .The i r ana lys i s demons t r a ted tha t the p resence o f r ad io log ica l e ros ionsand a pos i t ive d irect an t ig lobul in tes t (Mial l ' s cr i ter ia) were insuff ic ien t lysens i t ive . Add i t iona l f ea tu res such as the occu r rence o f rheumato id nod-u les , swea t ing pa lms and co ld b lue ex t r emi t ies were found to be p red ic -

tors of c l in ical d isease . In contras t to the f ind ings of Cobb e t a l (1955) ,m o r n in g s t i f f n e s s w as n o t f o u n d to b e a g o o d d i s c r im in a to r f o r RA ,ex cep t i n y o u n g e r ag e g r o u p s.

Bailli~re's Clinical Rheumatology- 287Vol. 9 , No. 2 , M ay 1995 Copy right 9 1995, by Bail l i rre TindallISBN 0-7 020 -19 39- 9 Al l r igh ts o f reproduction in any form reserved


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C R I T E R I A I N R E C E N T U S E

A . J . M A C G R E G O R

A R A c r it e ri a 1 9 5 6 - 1 9 6 1

I n 1 9 5 6 a c o m m i t t e e o f t h e A m e r i c a n R h e u m a t i s m A s s o c i a t io n ( A R A ) w a ses t ab l i shed to ob ta in u n i fo rmi ty in cases l i s ted as R A (Rop es e t al , 1956 ) .The com m i t t ee r ecog n ized tha t i t wo u ld be d i ff icu l t t o de t e rmine the l imi t so f t he d i agnos i s o f R A and a t t emp ted to c l ass ify the d i sease in to th reeca tego r i es : ' d e f in i t e ', ' p rob ab le ' and ' poss ib l e ' . The f i rs t two ca t ego r i eswe re in t ended fo r s tud ies o f t he cou rse , charact e ri s ti c s and t r ea tmen t o f RAwhi l e the l a t t e r ca t ego ry o f ' poss ib l e ' d i sease was in t ended as a means o fde tec t ing ea r ly, a typ ica l cases . It was em phas ized tha t the c r i te r ia w ere no tdes igned as d i agnos t i c a id s , bu t were mean t s imp ly as a t oo l fo r c l ass i -f icat ion.

The c r i t e r i a se l ec t ed were deve loped on the bas i s o f t he c l in i ca l exper i -e n c e o f th e m e m b e r s o f th e c o m m i t te e . A l is t w a s f o r m e d o f a ll th e m a n i -f e s ta t io n s o f R A w h i c h m i g h t h a v e s u f fi c ie n t d i a g n o s ti c v a l u e t o b e w o r t h yo f cons ide ra t ion . The ana ly s i s i nc luded da ta f rom the P i t t sbu rgh Ar th r i t i sS tudy (Cobb e t a l , 1955 ; Cobb e t a l , 1956 ) in add i t ion to da t a co l l ec t edf rom a num ber o f phys i c i ans in t e res t ed in rheumat i c d i seases in va r iouspar ts o f the Un i t ed S ta t es and Canada . Phys ic i ans w ere asked to se l ec t f romthe i r c l in ics o r p rac t i ces the f ive m os t r ecen t eases o f c l ass i ca l RA , f ivec a s e s o f p r o b a b l e R A a n d f iv e w i t h n o e v i d e n c e o f R A .

In a l l , 332 case r epo r t s were ob ta ined f rom 19 d i ff e ren t c i t i e s . Di seasecharac t e r is t i c s w ere chosen w h ich h ad the h ighes t spec i f i ci ty ( low es t f a l sepos i t i ve r a t e) fo r cl ass if i ca tion as ' d e f in i te ' and ' p roba b le ' d i sease and wi tha h igh sens i t i v i ty ( low fa l se nega t ive r a te ) fo r ' poss ib l e ' RA . The f ina l c ri t er i as e t i n c l u d e d s e r u m r h e u m a t o i d f a c t o r ( R F ) a n d e v i d e n c e o f e r o s i v e d i s e a s eon han d and foo t X- ray s (Tab le 1 ). In add i tion , da t a on the p resence o f am ucin c lo t , and charac t er i s ti c h i s to log ica l fea tu res bo th on syno v ia l b io psya n d b i o p s y o f r h e u m a t o i d n o d u l e s w e r e in c l ud e d . A n u m b e r o f c h a r ac t er -i s t i c s were e l imina ted inc lud ing weigh t l o ss , vasomoto r symptoms , pa ra -

es thes i ae , sp l en om ega ly, p e r ica rd it i s, my ocard i t i s , p l eu r isy, r ever sa l o f t hea lbum in /g lobu l in r a tio in the p l asma and th i cken ing o f t he pa lmar f asc i a.F iv e o f t he l i s ted e l even c r i t e ri a we re r equ i red fo r i nc lu s ion as ' d e f in it e '

RA and th ree fo r c l ass i f i ca t ion as ' p robab le ' RA. Fo r c l ass i f i ca t ion as' p rob ab le ' and ' de f in it e ' d i sease i t was a r equ i remen t t ha t so f t t i s sues w e l l i n g s h o u l d h a v e b e e n o b s e r v e d b y a p h y s i c i a n a n d m u s t h a v e b e e np resen t fo r a t l eas t 6 w eeks . Fo r ' poss ib l e ' R A the c ri t e ri a were l e s s s tr ic t.T h e r e q u i re d d u r a ti o n o f s y m p t o m s w a s 3 w e e k s a n d a h i s to r y r a th e r th a nthe o bse rva t ion o f j o in t swe l l ing was adeq ua te . In t e res t ing ly, i r it is w as a l soinc luded as a c r i te r ion o f poss ib l e RA .

Th e p ro b lem o f inc lud ing pa t ien t s wi th o the r rheumat i c d i seases wascons idered . I t was f e l t impor t an t no t t o exc lude cases o f degen era t ive jo in td i sease tha t had p ro g ressed to deve lo p RA . The r ig id c r i te r ia fo r ' p ro bab le 'and ' de f in i te ' d i sease w ere though t t o be su ffi c i en t t o have exc lud edu n c o m p l i c a t e d d e g e n e r a t iv e j o i n t d i s ea s e.

Th e c r i te r i a were , h ow ever, f e l t t o be in su ff i c i en t ly spec i f ic t o d i s tingu i sh


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Ta ble 1 . 1958 AR A diag nos t ic c r ite r ia for rheumato id a r thr it i s .*

289

1 . M o r n ing s t i f f ne s s2 . Pa in on mo t ion o r t e nde r ne s s i n a t l e a s t one j o in t ( obse r ve d by a phys i c i an )

3 . Sw el l ing ( sof t t i s sue th ickening or fluid, no t bony overgrow th a lone) in a t l eas t one jo in t( ob se r ve d by a ph y s i c ia n )4 . Sw e l l i ng ( obse r ve d by a phys i c ia n ) o f a t le a s t one o the r j o in t ( the i n te r va l be tw e e n tw o j o in t

i nvo lve m e n t s mu s t be no mor e tha n 3 mon ths )5 . Sy m me t r i c a l j o in t sw e l l i ng ( obse r ve d by a phys i c ia n ) w i th s imu l t a ne ous i nvo lve me n t o f the

sa me j o in t on bo th s i de s o f t he body ( b il a te r a l i nvo lve me n t o f the m id - pha la nge a l , M CPor M T P jo in t s i s a c c e p t a b l e w i th ou t a b so lu te sym me t r y ) . Te r mina l I P j o in t i nvo lve me n twi l l no t sa t i s fy the c r i te r ion .

6 . Su bc u t a ne ous nod u l e s ( obse r ve d by a phys i c ia n ) ove r bony p r omine nc e s , on e x t e nso rsur faces or in jux ta -a r t icu la r reg ion s

7 . X-ray cha nge s typ ica l o f rheum ato id a r thr it i s (wh ich mu st inc lude a t l eas t bon ydeca lc i f ica t ion loca l ized to or g rea tes t a round the inv olved jo in t s )

8 . Po s i t i ve a gg lu t ina t i on t e s t - - de m on s t r a t i on o f RF by a ny me thod w h ic h in tw o l a bo ra to r ie sha s be e n pos i t i ve in n o t ove r 5% o f no r m a l c on t r o l s - - - o r pos i t ive s t r e p toc oc c a lagglu t ina t ion tes t(1956 criteria: po sitive sheep c ell agglutination or positivestrepto cocc al agglutination test)

9. Poo r mu cin prec ip i ta te f rom synovia l f lu id10 . Cha rac te r i s t ic h i s to log ic chan ges in synovia l me m bran e11 . Cha rac te r i s t ic h i s to log ic chan ges in nodules

C la s s i c a l R A r e qu i r e s 7/11 c r i te r i a w i th 1 - 5 p r e se n t c on t i nuous ly f o r 6 w e e ks(not included in 1 956criteria)D e f in i t e RA r e qu i r e s 5/11 c r i te r i a w i th 1 - 5 p r e se n t c on t i nuous ly f o r 6 w e e ksP r ob a b l e RA r e qu i r e s 3/11 c r i te r i a w i th a t le a s t one o f 1 - 5 p r e se n t c on t i nuous ly f o r 6 w e e ks(1956criteria: 4 weeks)Poss ib l e R A r e qu i r e s tw o o f t he f o l l ow ing c r it e r ia a nd a t o ta l du r a t ion o f j o in t symp tom s o f a t l e a s tt h r e e w e e ks : ( 1 ) M o r n in g s t i f f n e s s ( 2 ) Te nde r ne s s o r pa in on mo t ion ( obse r ve d by a phy s i c ia n ) w i tha h i s t o r y o f r e c u r r e nc e o r p e r s i s te nc e f o r t h r e e w e e k s ( 3 ) H i s to r y o r obse r va ti on o f jo in t sw e l l ing ( 4 )Sub c u t a ne ous nod u l e s ( obse r ve d by a phys i c ia n ) ( 5 ) E l e va t e d s e d ime n ta t i on r a t e o r C - r e a c t i ve p r o t e in(6) Iritis.E xc lu s ion s - ( 1 ) Ty p i c a l r a sh o f SL E ( 2 ) H igh c onc e n t r a t ion o f L E c e l ls ( 3 ) H i s to log i c e v ide nc e o fpe r i a rt e r it i s nodosa ( 4 ) W e a kne s s o f t he ne c k , t r unk a nd pha r ynge a l musc l e s o r pe r s i s t e n t musc l esw e l l i ng o f d e r ma tom yos i t i s (5 ) D e f in i t e s c le r ode r ma ( 6 ) A c l in i c a l p i c tu re o f r he uma t i c f e ve r ( 7 ) Acl in ica l p ic ture of gou ty a r thr i t is (8 ) Tophi (9) Ac ute in fec t ious a r thr it i s (10) Ev idenc e of jo in ttubercu los i s (11) A c l in ica l p ic ture charac te r i s t ic o f Re i te r ' s syn drom e (12) A c l in ica l p ic turec h a r a c t e r is t ic o f sh ou lde r - h a nd synd r om e ( 13) A c l in i c a l p i c tu re o f hy pe r t r oph i c pu lmona r yos teoar thro pa thy (14) N euroar thropa thy (15) Hom ogen t i s ic ac id in the ur ine (16) His to log ic ev id enc eo f s a r c o id o r a pos i t i ve K v e im t e s t (1 7 ) M u l ti p le m ye loma ( 18 ) E r y tbe m a nodosum ( 19 ) L e uka e miao r l y m p h o m a (2 0 ) A g a m m a g l o b u l in a e m i a(not includ ed in 1956 criteria).* W here the 1958 c r i te r ia d i ffe r f rom the 1956 c r i te r ia , the var ia t ions in the 1956 c r i te r ia a re show nin i ta l icsA d a p t e d f r o m R ope s e t a l ( 1956 ) a nd R ope s e t a l (1958 ) f r om theBulletin on the Rheu ma tic Diseases,c o py r igh t 19. U s e d by pe r mi s s ion o f t he A r th r i ti s Founda t i on .

R A i n t h e p r e s e n c e o f c e r t a i n o t h e r r h e u m a t i c d i s e a s e s , s u c h a s s y s t e m i cl u p u s e r y t h e m a t o s u s ( S L E ) a n d g o u t . I t w a s f e l t b e st t o c la s s i f y i n d i v id u a l swi th t he se d i s ea se s s epa ra t e ly fo r compara t ive pu rposes . A l i s t o f

exc lus io ns w as p ub l i shed w i th t he cr it er ia s e t (Tab le 1 ). I t i s o f in t e r es t tono te t ha t pa t i en t s l abe l l ed a s rheuma to id spondy l i t i s , p so r i a s i s , u l ce ra t i vec o l it is a n d t h o s e w i th a n o n s e t o f d i s e a s e u n d e r t h e a g e o f 1 2 y e ar s w e r er e c o m m e n d e d t o b e i n c l u d e d i n t h e r h e u m a t o i d g r o u p s , a l t h o u g h i t w a ssug ges t ed t ha t t he se s hou ld be s epa ra te ly li s ted .

Af t e r 2 yea r s o f u se , t he ARA c r i t e r i a commi t t ee r ev i ewed the i r o r ig ina l


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cr it e ri a . T here w as ag reem en t tha t the c r i te r i a were no t su ff i ci en t ly r igo rous(Ropes e t a l , 1958 ) . Consequen t ly, an add i t iona l ca t ego ry o f ' c l a s s i ca l 'd i sease w as ad ded fo r wh ich seven o f t he 11 c r it e r ia had to be sa ti s fi ed . Al lo f t he f i rs t fi ve c r it e ri a had to be p resen t c on t inuo us ly fo r 6 w eek s fo r t heind iv idual to be c lass i f ied as hav in g ' c lass ica l ' o r 'def in i te ' d i sease .A gam m ag lo bu l in aem ia was add ed to the exc lu s ion c ri te r ia . A d i ff i cu l ty hadb e e n e n c o u n t e r e d i n a s s i g n i n g p o s i t i v i t y f o r R F a s m a n y a s s a y m e t h o d sw e r e i n u se . T h e c o m m i t t e e r e c o m m e n d e d t h e u s e o f a n y m e t h o d t h at h a dbeen demons t ra t ed by a t l eas t two l abo ra to r i es t o be pos i t i ve in l e s s t han5% o f no rm al con t ro l s. Th e f ina l c r it e ri a se t (t he 1958 A R A rev i sed c r i te r ia ,Tab le 1 ) ga ined widesp read accep tance and was u sed ex tens ive ly.

T h e c r i t e r i a w e r e r e v i e w e d a t a s y m p o s i u m o n P o p u l a t i o n S t u d i e s i nR e l a t i o n t o C h r o n i c R h e u m a t i s m , s p o n s o r e d b y th e C o u n c i l f o rI n t er n a ti o n a l O rg a n iz a ti o n s o f M e d i c a l S c i e n c e s ( C I O M S ) i n R o m e i n 1 9 6 1(Kel lg ren , 1962 ) . Two p rob lems had emerged in the i r u se . The f ina l t h reec r i te r i a based on invas ive t e s t s had p ro ved to be imprac t i ca l . Ad d i t iona l ly,i t was r ecogn ized tha t t he RA cr i t e r i a f a i l ed to encompass f ea tu res o f

T a b l e 2 . T he Rom e c r i te r i a f o r ina c t ive RA .

1 . A pas t h i s tory of po lyar thr i t i s2 . Sym me t r i c a l de f o r mi ty o f p e r i phe ra l j o in t s c ons is t i ng o f a nky lo s i s o r i rr e duc ib le

sub luxa ti o n , e spe c ia l l y o f t he la t er a l MT P o r M CP jo in t s; t he r e mus t be som e i nvo lve me n to f o ne ha nd o r f oo t ; i nvo lve me n t lim i t e d to l a rge j o in t s , suc h a s t he e lbow s o f kne e s doe snot sa t i s fy th i s c r i te r ion

3 Ra d io log i c a l c ha ng e s o f RA o f g r a de 2 o r mor e4 . Pos i t ive se ro logica l t es t fo r RF

D e f i n i t e R A requi res 3 /4 c r ite r iaP r o b a b l e RA requi res 2 /4 c r ite r iaA da p t e d f r o m K e l lg re n ( 1962 ) f r om theBulletin on the Rheumatic Diseases, copyr ig h t 19 . Use d byp e r mi s s ion o f t he A r th r i ti s Fou nda t ion .

i nac t ive d i sease. N ew c r i te r i a set s were p roposed : t he Ro m e (ac t ive ) and theR om e ( inac tive ) c r it e ri a . The c r it e r ia fo r ac t ive d i sease we re equ iva len t t othe 1958 cr i ter ia , e xc ep t that the f inal th ree e lem ents o f the cr i ter ia se t w ere

rem oved . Cr i t er i a fo r 'd e f in i t e ' and ' p ro bab le ' i nac t ive d i sease w ered e v i s e d ( Ta b l e 2 ) . A n a d d i t i o n a l c h a n g e s u g g e s t e d a t t h e s y m p o s i u m w a stha t anky los ing spondy l i t i s shou ld be ad ded to the l is t o f exc lu s ions .

N e w Yo r k C r i t e r i a , 1 9 6 6

Sho r t com ings in the cr i te r i a fo r i nac t ive d i sease were d i scussed a t t he Th i rdI n t er n a ti o n a l S y m p o s i u m o n P o p u l a t io n S t u d i es o f t h e R h e u m a t i c D i s e a s e sh e l d i n N e w Yo r k i n 1 9 6 6 ( B e n n e t t a n d B u r c h , 1 9 6 7 ; B e n n e t t a n d Wo o d ,1968) . I t was apparen t t ha t, i n popu la t ion s tud ies o f R A , the metho d o f

g roup ing o f c r it e r ia l i s ted in the Ro m e c r i te r ia was inadequ a te . Th ef r e q u e n c y o f o c c u r r e n c e o f m a n y o f t h e c h ar a ct e ri s ti c s i n c l u d e d h a d n o tbeen es t ab l i shed in no rmal popu la t ion samp les .

A s t u d y b y L a w r e n c e a n d W o o d ( 1 96 8 ) h ad e x a m i n e d d a ta f ro m s u r v ey si n N o r t h e r n E n g l a n d d u r i n g t h e y e a r s 1 9 5 4 - 1 9 6 1 a n d h a d d e m o n s t r a t e dtha t, i n com par i son wi th a c l in i ca l g rad ing o f RA, the 1958 c r it e r ia had


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been both insufficiently sensitive and specific, and had led to importantmisclassification of cases of osteoarthritis. Their analysis indicated thatidentifying the pattern of join t involvement was critical for case recognitionin the population.

Using these data, the 13 most important clinical variables that resulted inthe clinical classification of RA were incorporated into the format of theRome (inactive) criteria. Emphasis was placed on the specificity of thesevariables such that the new criteria included few false positive cases.Criteria with a low population prevalence, such as rheumatoid nodules,were not included. The result was a set of four criteria designed to identifycases o f both active and inactive disease in the population setting (the NewYork criteria, Table 3). Recommendations on summation of the criteriawere not made. Summation was considered unnecessary as long as the

Ta b le 3 . T h e N e w Yo rk c r it e ri a .

1 . A h i s to ry, p a s t o r p r e s e n t , o f a n e p i s o d e o f j o in t p a in i n v o lv in g th r e e o r mo re l imb jo in t s ,w i th o u t s t i p u l a ti o n a s t o d u ra t io n . E a c h g ro u p o f j o in t s ( e .g . P IP ) i s c o u n te d a s o n e j o in t ,e a c h s id e s c o re s s e p a ra t e ly

2 . S w e l l i n g , lim i t a t i o n o f mo t io n , s u b lu x a t io n o r a n k y lo s i s o f a t l e a s t t h r e e l imb jo in t s(exc lud in g : DIP, 5 th PIP, 1s t c a rp o me ta c a rp a l j o in t , I s t M T P a n d h ip s ) w i th s y m m e t ry o fa t l e a s t o n e j o in t p a i r. T h e re m u s t b e i n v o lv e m e n t o f o n e h a n d , w r i s t o r f o o t , a sin v o lv e m e n t l im i t e d t o l a rg e j o in t s s u c h a s e lb o w s o r k n e e s d o e s n o t s a t i s fy t h i s c ri t er io n .S u b ln x a t io n o f t h e l a t er a l M T P s m u s t b e i r r ed u c ib le .

3 . R a d io lo g ic a l f e a tu r e s o f g r a d e 2 o r mo re e ro s iv e a r th ri t is in t h e h a n d s , w r i s t s o r f ee t .

4 . P o s i t i v e R F b y a m e th o d c o n t ro ll e d b y p e r io d i c te s t i n g o f r e f e r e n c e s e r a a n d b y e x c h a n g eo f s e r a w i th o th e r l a b o ra to r i e s.

N o r e c o m m e n d a t i o n s f o r s u m m a t i o n w e r e m a d e .A d a p t e d f r o m B e n n e t t a n d B u r c h ( 1 9 6 7) f r o m t h eBulletin o f the Rheumatic Diseases,c o p y r ig h t 1 9.U s e d b y p e r m i s s i o n o f t h e A r t h ri t is F o u n d a t i o n .

distribution of each criterion was reported individually. Exclusions werefelt to be inappropriate in the population setting where there was anemphasis on inc luding all possible features of disease.

A R A r e v i s ed c r i te r ia , 1 9 8 7

In 1983 an ARA subcommittee was appointed to revise the 1958 RAcriteria. Their recommendations were subsequently published as the 1987revised ARA criteria (Arnett et al, 1988). The modifications weredeveloped in recognition of the changes in the clinical definition of RAover the preceding 30 years. In particular, the committee cited the HLAB27-associated spondyloarthropathies, the pseudorheumatoid form ofcalcium pyrophosphate dihydrate deposition disease, polymyalgiarheumatica and Lyme disease as clinical entities hitherto included as

seronegative RA, which would no longer be included in the definition. Itwas also recognized that, in practice, the distinction between 'classical' and'definite' RA had not proved useful and that patients previously classifiedas 'probable' RA most commonly did not have the disease. Criteriainvolving invasive procedures were again noted to be impractical. Therewas concern that the 'exclusions' proposed with the criteria were difficult


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292 a . J . MACGREGOR

t o a p p ly. T h e A R A c r it e ri a s u b c o m m i t t e e s e t t h e m s e l v e s t h e t a s k o fdef in ing ne w c r i te r i a t ha t wo u ld be m ore sens i t i ve and spec i f ic and r equ i reda s t r ic ter def in i t ion of RA .

The rev i sed c r i t e r i a se t was deve loped by compar ing c l in i ca l f ea tu resreco rd ed in pa t i en ts and con t ro l s r ec ru i ted f ro m un iver s i ty hosp i t a l c lin i csand p r iva t e p rac t i ces . Pa t i en t s were r ec ru i t ed consecu t ive ly and compr i sed366 adu l t s ov er t he age o f 16 year s wi th es t ab l ished RA . Con t ro l s w eret aken as the nex t consecu t ive pa t i en t wi th a rheumat i c d i sease o the r t hanRA . Pa t i en t s wi th loca l ized rheumat i c cond i t ions w ere no t i nc luded . Th e'go ld s t andard ' u sed fo r ana ly s i s was the c lin i ca l op in ion o f t he pane l o fphys ic i ans .

D a t a w e r e c o l l e c t e d in t h e f o r m a t o f t h e 1 9 5 8 A R A c r it e ri a a n d t h e N e wY ork c r i te r ia . Gro ups o f c r i te r i a we re d iv ided in to com pon en t s i n ana t t emp t to es t ab l i sh the mos t d i sc r imina t ing de f in i t i ons . Two d i ff e ren ts t a ti s ti ca l ana ly ses we re pe r fo rm ed on the poo led da ta . In the f ir st , com bi -na t ions o f c r i te r i a were es t ab l i shed tha t were the mo s t sens i t i ve and them os t spec i f i c fo r d i s t ingu i sh ing R A and n on -RA in cases and con t ro l s. Thesecon d meth od invo lved a p rocess o f recu r s ive pa rt i ti on ing (Bre im an e t al ,1984) in which a h ierarch ical c lass i f ica t ion t ree i s es tab l i shed to ass ign ad iagnos i s based on da ta f rom the g roup as a who le .

In th is analys is , the c l in ica l cr i ter ia wi th the h ighes t combined sens i t iv i tyand spec i f i c ity we re those wh ich r e f l ec t ed the charact e r is t ic pa t t e rn o f j o in ti n v o l v e m e n t i n R A . T h u s , w r i s t o r m e t a c a r p o p h a l a n g e a l ( M C P ) i n v o l v e -men t had an accu racy (mean sens i t i v i ty and spec i f i c i ty ) o f 86 .1% andi n v o l v e m e n t o f th r e e o r m o r e jo i n t a r e as h a d a n a c c u r a c y o f 8 7 . 4 %.Sym m et r i ca l a r th r it is i n any r eg ion had an accu rac y o f 84 .3%. The se ind i-v idua l c r i te r i a had a s imi l a r accu racy to the Ne w Y ork c r i t e rion o f j o in tswel l ing (87 .4%) . The ana ly s i s a l so con f i rmed tha t the spec i f i c i ty o f t hemo rn ing s t i ffness c r it e r ion was g rea t ly enhanced i f t he du ra t ion o f morn ings t i ffness w as spec i f i ed as g rea t e r t han on e hou r.

The f ina l fo rm u la t ion o f the c r i te r ia (Tab le 4 ) r ep laced the fo rm erca tego r i es o f ' c l a s s i ca l ' and ' de f in i t e ' d i sease wi th the s ing le d i sease

c a t e g o r y o f 'r h e u m a t o i d a r th r it is '. ' P r o b a b l e ' a n d ' p o s s i b l e ' R A w e r erem oved . Th e c r i t er i a cons ide red on ly da t a f rom 14 spec i f i ed jo in t a reas( seven on each s ide ) . In fo rm at ion on inv o lvem en t o f t he shou lder s , wh ichwas accep ted in p rev ious c r i t e r i a se t s , was no longer inc luded . The 1987cr i ter ia se t a l so rep la ced the sec ond , th i rd and fo ur th cr i ter ia o f the 1958 cr i -ter ia wi th ' a rth r i ti s o f th ree o r m ore jo i n t areas ' and ' a rth r i ti s o f the handjo in t s ' . R heu m ato id f ac to r, t he p resence o f r ad io log ica l e ro s ions andrheum ato id nod u les were r e ta ined . The r ad iog raph ic r equ i remen t wasres t r ic t ed to in t e rp re t a tion o f a s ing le pos t e roan te r io r r ad iog raph o f bo thhands . The c r i t e r ia i nvo lv ing jo in t a sp i ra t ion , synov ia l b io psy and

r h e u m a t o i d n o d u l e b i o p s y w e r e d e l e t e d . E x c l u s i o n s w e r e n o t s p e c i f i e d i nthe new c r i te r i a se t t o r ender them mo re su i t ab le fo r popu la t ion s tud ies .

In the c l ass if i ca tion t r ee fo rmu la t ion (F igu re 1 ), t he popu la t ion o f casesand con t ro l s was d iv ided in to e igh t subse t s , f i ve r ep resen t ing pa t i en t sc l ass if i ed as R A. The schem e a l low ed sw el l ing o f t he wr i s ts t o subs t i tu t efo r RF, and swel l ing o f t he M C P jo in t s t o subs t i t u t e fo r r ad io log ica l


7/18

C L A S S I F I C AT I O N C R I T E R I A F O R R A

Ta b le 4 . T h e r e v i s e d 1 9 8 7 A R A c r i te r ia .

2 9 3

1 . M o rn in g s t i f f n e s s

2 . Ar th r i t i s in th ree o rm o r e j o i n t a r e as *3 . A r th r i ti s o f h a n d jo in t s4 . S y m me t r i c a l a r th r i ti s

5 . R h e u m a t o i d n o d u l e s

6 . R h e u m a t o i d f a ct o r7 . R a d i o g r a p h s c h a n g e s

M o rn in g s t i f f n e s s i n a n d a ro u n d th e j o in t s , l a s ti n g a t l e a s t o n eh o u r b e fo r e m a x i m a l i m p r o v e m e n t

S o f t t i s s u e s w e l l i n g o r f lu id (n o t b o n y o v e rg ro w th ) o b s e rv e d b y ap h y s i c i a n , p r e s e n t s imu l t a n e o u s ly fo r a t l e a st 6 w e e k sS w e l l i n g o f w r i s t M C P o r P IP fo r a t l e as t 6 w e e k sS i m u l t a n e o u s i n v o l v e m e n t o f t h e s a m e j o i n t a r e a s ( d e fi n e d i n 2 )

o n b o th s id e s o f t h e b o d y (b i l at e ra l i n v o lv e m e n t o f P IP s , M C P so r M T P s i s a cc e p ta b l e w i th o u t a b s o lu t e s y m me t ry ) f o r a t l e a s t6 w e e k s

S u b c u t a n e o u s n o d u l e s o v e r b o n y p r o m i n e n c e s , o r e x t e n s o rs u r f a c e s , o r in j u x t a - a r ti c u l a r re g io n s , o b s e rv e d b y a p h y s i c i a n

D e te c t e d b y a me th o d p o s i t i v e in l e s s t h a n 5 % n o rm a l c o n t ro l sTy p ic a l o f R A o n p o s t e ro a n te r io r h a n d a n d w r i s t r a d io g ra p h s

w h i c h m u s t i n c lu d e e r o s i o n s o r u n e q u i v o c a l b o n y

d e c a l ci f ic a t io n lo c a l i z e d to o r m o s t ma rk e d a d j a c e n t to t h ein v o lv e d jo in t s (O A c h a n g e s a lo n e d o n o t q u a l i f y )

* P ro p o s e d a r e a s: r i g h t o r l e f t P IP, M C P, w r i s t, e lb o w, k n e e , a n k le , M T P.A t l e a s t f o u r c r i t e r ia m u s t b e fu l fi l le d fo r c l a s s i fi c a ti o n a s R A .P a t i e n t s w i th tw o c l i n ic a l d i a g n o s e s a r e n o t e x c lu d e d .A d a p te d f ro m A rn e t t e t al ( 1 9 88 ) .A d a p t e d f r o m t h ePrime r on the Rheumatic Diseases, 10th edn , cop yr igh t 1993 .

I A rthrit is of three or m ore oint areas In o . . . . . . . . . . . . .

I X ' m ychanges ( . swel l ing:wrist) I' .w e l l in O :M o P I I I .h e u m a to ,d ,a c t o r

I R(hsEwU~li~~]i:dfaCtt~ I ~ '~ / i9 9 I Sym m etrica l I/ ' , I swe l l in ~ lI !~ e ~ l ~ o / .

I ~ yes "no/IS w e llin g M C P I / ~ # iI I andwr is t I / v l/ / "" . / I S w el lingM C Py e n ~ " ~ .i o r w r is t I /

"" "- " 'o /;

( R A ~ ( n o t R A )

F ig u re 1 . 1 9 8 7 A R A d e c i s io n tr e e a lg o r i t h m fo r R A c l a s si f ic a t io n .* Va r i a b l e s i n p a r e n th e s e s c a n b e u s e d w h e n d a t a o n th e f i r st l is t e d v a r i a b le i s u n a v a i l a b le . A d a p te df r o m A m e t t e t a l ( 1 98 8 ).


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29 4 A .J . MACGREGOR

chang es wh en these da t a were no t ava i l ab le . Da ta on morn ing s t i ffness andrheumato id nodu les were no t r equ i red . In t e res t ing ly, by th i s method them ajo r i ty o f i nd iv idua l s a re co r rec t ly c l ass i fi ed by the s im p le r equ i rem en t o f

a r th r i ti s a ff ec t ing th ree o r mo re jo in t a reas wi th typ ica l f ind ings on handrad iog raphs (o r wi th M C P swel l ing i f t hese da t a a re no t ava i l ab le ) .S w e l l i n g o f t w o o r l es s j o i n t a r e as i n t h e a b s e n c e o f R F e x c l u d e s R A i n th em ajo r i ty o f i nd iv idua l s.

VA L I D AT I O N

R e q u i r e m e n t s o f d is e a s e c l as s if ic a t io n

The h i s to r i cal d eve lo pm en t o f c lass if i ca tion c r i te r i a in R A has r e f l ec t ed thed i ff e ren t r equ i remen t s fo r case r ecogn i t ion in c lin i c and popu la t ion se tt ings .In the c lin i c, t he r equ i remen t i s t o d i st i ngu i sh R A f ro m o ther in f l amm ato ryar th r it i des . Giv en tha t f ew cases o f mi ld o r i nac t ive d i sease a re l ike ly to berep resen ted , c r i t e ri a t hat have be en dev e lop ed in c l in i c popu la t ions emp ha-s i ze f ea tu res o f ac t ive d i sease . Mi t che l l and F r i es (1982 ) have d em ons t ra t edtha t fo r t he 1958 A R A cr i te r i a the re is a c lo se assoc ia tion be tw een the num -be r o f cr i ter ia sa t i s f ied and th e seve r i ty o f c l in ica l d i sease .

By con t ras t , case r ecogn i t ion in the popu la t ion needs to inc lude mi lde rand inac t ive d i sease and mu s t d i s ti ngu i sh these f ro m cases o f o st eoarth r it i s,w h ich w i l l com pr i se the m ajo r i ty o f no n -R A jo in t d i sease in th i s se tt ing .O n l y t h e N e w Yo r k c r it e ri a ( Ta b l e 3 ) w e r e d e v e l o p e d s p e c i f ic a ll y f o r u s ei n p o p u l a t i o n s t u d ie s . A l t h o u g h e l e m e n t s o f t he N e w Yo r k c r it e ri a w e r einco rpo ra t ed in to the 1987 rev i s ion o f t he A R A cr it e ri a , t he l a tt e r cr i te r i aw e r e n o t d e r i v e d b y s t u d y i n g a p o p u l a t io n s a m p le .

The fo l lowing two sec t ions cons ide r con temporary s tud ies where c r i t e r i ain cu r ren t u se h ave b een va l ida t ed ( a ) i n the se tt ing o f hosp i t a ls and o u t -pat ien t c l in ics and (b) in popula t ion and fami ly s tud ies .

C a s e d e f i n i t i o n i n t h e c l i n i cI n t h e d e v e l o p m e n t o f th e 1 9 8 7 A R A c l as s if ic a ti o n s c h e m e s , t h e n e wcr i t e r i a (bo th in ' fou r f rom seven ' (4 /7 ) and dec i s ion t r ee (DT) fo rmat s )w e r e f o u n d t o b e o f c o m p a r a b l e s e n si ti v it y b u t e n h a n c e d s p e c if i ci t y w h e ncompared wi th the 1958 cr i ter ia (Arnet t e t a l , 1988) . The inves t igators a l soana ly sed the ce r t a in ty o f d i agnos i s i n those tha t had b een m isc lass if i ed . Asco re w as a l loca t ed to each pa t ien t based on the op in ion o f t he examin ingphys ic i an u s ing a sca l e f rom 0 (no t RA ) to 100 (de f in i t e RA ) . The averagesco re among those c l ass i f i ed as RA was 91 and among those c l ass i f i ed as

n o t R A w a s 5 b y b o t h A R A ( 4 / 7 ) a nd A R A ( D T ) m e t h o d s . O f th o s epa t i en ts t ha t were misc l assi f ied , t he ce r t a in ty sco res were c lo se to the mid -range fo r bo th cases and con t ro l s , sugges t ing uncer t a in ty abou t t heo r ig ina l d i agnos i s i n these ind iv idua l s . The au tho r s conc luded tha t t hem easu re d sens i t iv i ty and spec i f ic i ty o f t he new c r i te r i a se ts had under-s ta ted thei r t rue accuracy.


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C L A S S I F I C AT I O N C R I T E R I A F O R R A 2 9 5

g

u~~a

01

~ , I o ~ ~ oo o o

I ~ ~ = ~ ~ ' ~

~ o . ~,

o~

~ o . o ~~ o ~


10/18

2 9 6 A . J . M A C G R E G O R

I t is to be exp ec ted tha t t he mo s t op t imis t ic a s sessm en t o f t he 19 87cr i t e r i a se t s wou ld be ob ta ined by examin ing the i r pe r fo rmance in thep o p u l a t i o n f r o m w h i c h t h e y w e r e d e r i v e d . D a t a a r e n o w a v a i l a b l e f r o m an u m b e r o f s tu d i es w h i c h h a v e c o m p a r e d t h e p e r f o r m a n c e o f t h e 1 9 5 8 a n d1987 cr i ter ia in hosp i ta l c l in ic se t t ings (Table 5 ) . In genera l , the f ind ingscon f i rm tha t the 1987 c r it e r ia a re o f enhanced spec i f ic i ty bu t r edu cedsensi t iv i ty.

T h e l a c k o f s en s i ti v it y o f th e 1 9 8 7 A R A c r it er ia w h e n c o m p a r e d w i t h t h e1 9 5 8 c r it e ri a a p p e a rs t o b e m o r e p r o n o u n c e d f o r n e w l y d i a g n o s e d c a s e s o fR A . T h i s h a s b e e n e x a m i n e d f u rt h e r b y M o e n s e t al ( 1 9 9 2 ) in t w o g r o u p so f ind iv idua l s p resen t ing to the ou tpa t i en t depar tmen t a t t he Jan vanB r e e m a n I n s t i t u t e i n A m s t e r d a m . R e c o r d s w e r e e x a m i n e d ( a ) r e t r o -spec t ive ly f rom 1338 pa t i en t s wi th a c l in i ca l d i agnos i s o f ' d e f in i t e ' o r' c la s s i c a l' R A a n d ( b ) p r o s p e c t i v e l y fr o m n e w l y r e f er r ed c a s e s o f w h o m 9 3had a ce r ta in d i agno s i s o f R A and 1357 had ne i the r ce rt a in no r poss ib l ed iagno ses o f RA . Th e l a tt e r ac t ed as con t ro l s . U s ing da ta f rom the f ir s t v i s i to f t he r e t ro spec t ive pa t i en ts , t he sens i t i v i ty o f t he 1987 AR A (4 /7 ) c r i t er i awas 66 % com pared wi th 71% fo r t he 1958 c r it e ri a (Tab le 5 ). The se va lueswere inc reased by inco rpo ra t ing da ta f rom the fo l low-up v i s i t s . In thep ros pec t iv e g roup , t he sens i t i v i ty o f t he 1987 A RA (4 /7 ) c r i t e ri a was aga inlow er than the 1958 c ri t e ri a (82% com pared w i th 86%) .

Th e lack of sens i t iv i ty wa s a t t r ibu ted to the fa i lu re o f the 1987 cr i ter ia,un l ike the 1958 c ri te r ia , t o sp ec i fy exp l i c it l y the t im e in t erva l du r ing wh ichcr i ter ia should b e fu l f i lled . Fur the rmo re , the rad io lo g ical cr i ter ion of handinvo lvemen t f a i l ed to iden t i fy e ro s ive d i sease in 12 ou t o f 17 casesc l ass i f i ed as f a l se nega t ive in whom there was c l in i ca l o r r ad io log ica le v i d e n c e o f m e t a ta r s o p h a la n g e a l ( M T P ) i n v o l v e m e n t . T h e v a l u e o f i n c lu d -i n g M T P i n v o l v e m e n t f o r c a se r ec o g n i ti o n i n e a rl y R A h a s a l so b e e n n o t e dby o ther s (Pa imela , 1992 ; Symmons e t a l , 1994 ) .

T h e u t i li ty o f e x c l u d i n g n a m e d d i a g n o s e s w a s a ls o e x a m i n e d b y M o e n se t a l (1992 ) . The i r ana ly s i s o f f a l se pos i t ive cases in the p rospe c t ive g roupsugg es t ed tha t any app rop r i a t e l i st o f exc lu s ions w ou ld need to have been

at leas t as long as that g iven wi th the 1958 cr i ter ia . The comparab lespec i f ic i t ie s o f t he 1958 and 1987 c r it e ri a sug ges t ed tha t the u se o f suchexc lu s ion c r i t e r i a was , however, unnecessa ry. These f ind ings con t ras t wi ththose o f Lev in e t al (1989 ) w ho repo r t ed that t he spec i f ic i ty o f t he 1987cr i ter ia was reduced in compar ison wi th the 1958 cr i ter ia . In thei r s tudy, ah i g h p r o p o r t i o n o f f al s e p o s i t iv e s w a s f o u n d a m o n g c o n t ro l s w i t h S L E , p s o -r ia t ic ar th r i t i s and gout . These resu l t s suggest a g reater need for exclus ionsi n s e t ti n g s w h e r e a h ig h p r o p o r ti o n o f n o n - R A c a s es h a v e o t h e r in f l am m a -tory ar th r it ides .

C a s e d e f i n i ti o n in p o p u l a t i o n a n d f a m i ly s t u d i e s

There h ave bee n f ew s tud ies compar ing the pe r fo rm ance o f ex i s t ing cr i te r i ase ts in popu la t ions wi th d i sease and none as ye t compar ing the pe r fo rm anceo f the 1987 c r i te r i a wi th the N ew Y ork c r i te r i a t o assess whe ther t hey a rean a deq uate subst i tu te in th i s se t ting . Re cen t ly, as par t o f a larger s tud y of


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C L A S S I F I C A T I O N C R I T E R I A F O R R A 297

o u t c o m e a s s e s s m e n t i n R A , J a c o b s o n e t a l ( 1 9 9 4 ) h a v e c o m p a r e d t h eper fo rm ance o f t he Ro m e c r it e r ia and the 1987 A R A cr i te r ia . The i r ana ly s i swas based on c ro ss - sec t iona l and long i tud ina l da t a f rom repea ted hea l thexam ina t ions o f 3509 P ima Ind ians. C l in i ca l d i agnos i s w as u sed as the' go ld s t andard ' fo r com par i son . T hey dem ons t ra t ed tha t, wh i l e bo th c ri t er i ase ts w ere o f comp arab le spec i fi c i ty, t he 1987 c ri t er i a had sub s t an t ia l lyreduced sens i t i v i ty. The 1987 ARA cr i t e r i a i den t i f i ed on ly a subse tcom pr i s ing 50% o f those iden ti f ied by the Ro m e (ac t ive ) c ri te r ia . I t wasno ted tha t t he sens i t i v ity o f bo th se ts was enhanced i f t hey w ere com binedwi th the Rome c r i t e r i a fo r i nac t ive d i sease o r equa l ly i f da t a f rom se r i a lexam ina t ions were t aken in to accoun t . These r esu l ts i nd ica t e tha t the 1987A R A cr i te r i a m ay fa i l t o i den t i fy m i ld o r i nac t ive d i sease . Haka la e t a l(1993 ) h ave a l so r epo r t ed tha t t he 1987 c ri te r i a on ly r ecogn ize severe RAin a popu la t ion samp le .

The im por t anc e o f i nco rpo ra t ing da ta on r emi t ted d i sease in popu la t ions tud ies to assess the occu r rence o f d i sease du r ing the l i fe t ime o f t he ind i -v idua l f rom a s ing le examina t ion has r ecen t ly been s t r essed (MacGrego rand S i lman , 1992 ). Tw o s tud ies by Ca thcar t and O 'Su l l iva n in Sudb ury,Massachuse t t s (Ca thcar t and O 'Su l l ivan , 1970 ; O 'Su l l ivan and Ca thcar t ,1972) i l lus t ra te the im po r tance o f th i s i ssue . The d isea se s ta tus o f a g rou pof 4552 ind iv idua l s w as assessed over a 5 -yea r i n te rval . Def in i t e R A wasiden t i f i ed a t base l ine in 0 .87% us ing the 1958 ARA cr i t e r i a bu t on ly in0 . 3 7 % u s i n g t h e N e w Yo r k c ri te ri a. A t f o l l o w u p 6 5 % o f t h o s e w h oor ig ina l ly fu l f i ll ed the Ne w Y ork c r it e ri a con t inued to be c l ass i fi ed as hav ingR A wh ereas on ly 36 % o f those o r ig ina l ly c l ass if i ed as hav ing def in it e R Aby the 1958 c r i t e r i a r emained in tha t ca t ego ry. The f ind ings demons t ra t ethat the 1958 cr i ter ia , un l ik e the Ne w Y ork cr i ter ia, a re affected byf luc tua t ions o f d i sease ac tiv i ty. Th e r esu l ts a l so sugg es t tha t t he N ew Yo rkcr i te r i a ma y b e too spec i f i c and ma y fa i l to r ecogn ize cases o f mi ld d i sease .

W e h a v e r e c e n t l y e x a m i n e d t h e p e r f o r m a n c e o f t h e N e w Yo r k a n d 1 9 8 7A R A cr i te r i a i n a twin s tud y o f R A wh ere the re was a c lea r r equ i remen t t oinc lude as cases those ind iv idua l s wi th inac t ive d i sease (MacGrego r e t a l ,

1994 ). The sam p le o f twins w as de r ived f rom (a ) a p ro spe c t ive ou tpa t i en tsu rvey and (b ) cases r ec ru i t ed f rom the genera l popu la t ion by a med iacam paign (S i lman e t a l, 1993 ) . The ' go ld s t andard ' fo r com par i son w as thed iagnos i s o f the r e fe r r ing p hys ic i an . The im por t ance o f inco rpo ra t ing d a taon pas t ev id ence o f d i sease ac tiv i ty on the pe r fo rm ance o f t he 1987 4 /7 andD T c r i te r i a was exam ined by adap t ing the fo rmat o f t he cr i te r ia ( a ) torecogn ize on ly cu r ren t f ea tu res o f d i sease and (b ) to inco rpo ra t e da t a ond i sease ac t iv i ty ' ev e r ' . T he l a t t er adap ta t ion a l low ed jo in t de fo rm i ty tosubs t i t u t e fo r j o in t swe l l ing and inco rpo ra t ed pas t da t a on RF se ropos i t i v i tyand the p resence o f rheum ato id n odu les (T ab le 6) .

Our ana ly s i s showed tha t c r i t e r i a wh ich on ly r ecogn ize cu r ren t ly ac t ived i sease subs t an t i a l ly underes t imate the l i f e t ime cumula t ive p reva lence o fR A . H o w e v e r, w h e n t h e 1 9 8 7 cr it e ri a w e r e a d a p te d t o in c o r p o r at e e v i d e n c eo f pas t d i sease , t he ir sens i t iv i ty was g rea t ly enhanced . Th e m od i f i ed 1987cr i te r i a had a s im i l a r accu racy (87% ) to tha t o f t he New Yo rk c r it e ri a u s ing' t h ree f rom fou r ' a s t he cu t -o ff po in t (86%) .


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2 9 8 A . J . M A C G R E G O R

T a b l e 6 . F o rma t fo r a p p l i c a ti o n o f t h e r e v i s e d 1 9 8 7 A R A c r i t e ri a to p o p u la t i o n a n d f a m i ly s tu d i es .

1 . M o rn in g s t i f f n e s s

2 . Ar th r i t i s in a t leas tt h r e e j o in t a r e a s *

3 . A r th r i ti s o f h a n d s

4 . S y m me t r i c a l a r th ri t is

5 . R h e u m a t o i d n o d u l e s

6 . R h e u m a t o i d f a ct o r

7 . R a d i o g r a p h c h a n g e s

M o rn in g s t i f f n e s s i n a n d a ro u n d th e j o in t s l a s t i n g a t l e a st o n e h o u rb e f o re m a x i m a l i m p r o v e m e n t at a n y t i m e i n t h e d i s e a se c o u r s e

S o f t t i s s u e s w e l l i n g o r f l uid o b s e rv e d b y a p h y s i c i a n , w i ths w e l l i n g a t c u rr e n t e x a m i n a t i o n o r d e f o r m i t y a n d a d o c u m e n t e dh i s to ry o f s w e l l i n g

S w e l l i n g o f w r i s t, M C P o r P IP w i th s w e l l i n g a t c u r re n te x a m i n a t i o n o r d e f o r m i t y a n d a d o c u m e n t e d h i s t o ry o f s w e l l i n g

S i m u l t a n e o u s i n v o l v e m e n t o f t h e s a m e j o i n t a r e a s ( d e fi n ed i n 2 )o n b o th s id e s o f t h e b o d y (b i l at e ra l i n v o lv e m e n t o f P IP s , M C P so r M T P s i s ac c e p ta b l e w i t h o u t a b s o l u te s y m m e t r y ) w i t hs w e l l i n g at c u r r e n t e x a m i n a t io n o r d e f o r m i t y a n d a d o c u m e n t e dh i s to ry o f s w e l l i n g

O v e r b o n y p r o m i n e n c e s o r e x t e n s o r s u r f a c e s, o r i n j u x t a - a rt i c u la rr e g io n s , o b s e rv e d b y a p h y s i c i a n a n d p r e s e n t a t c u r r e n t

e x a m i n a t i o n o r d o c u m e n t e d i n t h e p a s tB y a m e th o d p o s i t i v e in l e s s th a n 5 % n o rm a l c o n t ro ls a t c u r r e n te x a m i n a t i o n o r d o c u m e n t e d t o h a v e b e e n p o s i ti v e i n t h e p a s tb y a n y a s s a y m e t h o d

Ty p ic a l o f R A o n p o s t e ro a n te r io r h a n d a n d w r i s t r a d io g ra p h sw h i c h m u s t i n c l u d e e ro s i o n s o r u n e q u i v o c a l b o n yd e c a l ci f ic a t io n lo c a l i z e d in o r m o s t m a rk e d a d j a c e n t t o t h ein v o lv e d jo in t s (O A c h a n g e s a lo n e d o n o t q u a l i f y )

* A s d e f in e d in Ta b le 4 .A t l e a s t f o u r c r i te r ia m u s t b e fu l fi l le d fo r c l a s s i fi c a ti o n a s R A .A d a p te d f ro m A rn e t t e t al ( 1 9 8 8 ) a n d M a c G re g o r e t a l (1 9 9 4 ) .

The New York criteria have not found widespread acceptance over theyears because of their cumbersome formulation (Arnett et al, 1988). Theresults from this analysis of twins have indicated that the 1987 ARAcriteria, applied in a way which incorporates past occurrence of disease,would form an adequate substitute for the New York criteria in studies inwhich there was a requirement to measure the lifetime cumulativeprevalence o f disease. This method of application of the 1987 criteria wasendorsed by the American College of Rheumatology (ACR) criteria

committee.

D I S C U S S I O N

One c r i t i c i sm o f t he p re sen t app roach to c l a s s i f i c a t i on i s t ha t i t r e su l t s i na s s i g n m e n t o f t h e la b e l R A t o in d i v i d u a l s w h o r e p re se n t m a n y d i ff e r en tpa r ts o f a w id e s pec t ru m o f c li n i ca l d i s ea se . Th i s c r i ti c i sm i s , in pa r ti cu l a r,l e v e l le d a t m e t h o d s o f c la s s if ic a t io n i n w h i c h a n y c o m b i n a t i o n o f c r it er iaf rom a g ive n se t m ay be s a t i s f ied t o pe rm i t c l a s s i fi c a t ion a s R A as l ong a s

a c er ta in t h r e s h o l d n u m b e r is a t t a in e d ( f or e x a m p l e , 4 i n t h e 1 9 8 7 A R Acr it e ri a ) (A bra m son , 1 967) . Ed wa rds (19 88) ha s c r i ti c ized th i s ' de li be ra teh e t e r o g e n e i t y ' a n d h a s s u g g e s t e d t h a t t h er e ar e c o m p e l l i n g r e a s o n s f o rus ing qu i t e d i ff e r en t s e l ec t i on c r i t e r i a when s tudy ing , fo r example , t hena tu ra l h i s to ry o f ea r ly pe r iphe ra l j o in t syn ov i t i s o r t he p l ace o f au rano f inin t h e tr e a tm e n t o f c h r o n ic s y n o v i t is . M a u e t a l ( 1 9 8 9 ) r e c o g n i z e d t h is i s s u e


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as a pa r t i cu la r p ro b lem in the s tudy o f ea rly RA and have adv oca ted the u seo f de t a i led de sc r ip t ive d i agnoses as an a l t e rna t ive me thod fo r d i seasec l ass if i ca tion w hen s tudy ing the na tu ra l h i s to ry o f t he d i sease .

S i lman (1988 ) , ho we ver, a rgues tha t it i s un l ike ly tha t t he re wo u ld beag reem en t on such desc r ip t ive c l assi f ica t ion schemes . I t is o f i n t eres t t ono te tha t t he New York c l ass i f i ca t ion scheme, wh ich has a desc r ip t ivef o r m a t ( Ta b l e 3 ) , h a s b e e n f o u n d t o b e t o o c u m b e r s o m e f o r p r a c t i c a l u s eand has no t been adop ted wide ly (Arne t t e t a l , 1988 ) . A fu r the r conse-q u e n c e o f ac h i e v i n g g r e a t e r h o m o g e n e i t y t h r o u g h m o r e d e s c r ip t i v e d is e a s edef in it i on w ou ld be to r educe the s i ze o f the ava i l ab le popu la t ion fo r s tudy,hence reduce s ta t i s t ica l val id i ty.

A re l a ted co ncern i s t ha t the m ethod o f d i sease cl assi f ica t ion i s based onc i rcu la r r eason ing (Hea ley, 1990 ) and the refo re wi l l be max imal ly e ff ic i en ta t c l ass i fy ing as RA cases that con fo rm to a st e reo type . Th i s app roach m aylead to inc lu s ion o f subse t s i n to the c l assi f ica t ion o f RA , w h ich m ay rep re -sen t d i s t inc t d i sease en t i ti e s i f the i r na tu ra l h i s to ry w ere fo l lo we d fo r p ro -longed per iods . Se ronega t ive RA, fo r example , may rep resen t a d i sc re t ed i sease en t i t y, a l t hough th i s con t inues to be d i spu ted (Ca l in and Marks ,1981 ; Mas i and Fe igenbaum, 1983 ) . La te onse t s t e ro id - respons ivesym me t r i ca l w r i s t synov i t i s may a l so r ep resen t a d i s t inc t d i sease tha t wo u ldbe c l ass i f i ed as RA by the cu r ren t c r i t e r i a (Hea ley and Shee t s , 1988 ) .Co nve rse ly, j uv en i l e rheu mato id a r th r it is i s conven t iona l ly exc luded by ana r b it r ar y a g e c u t - o ff , y e t m a y m o r e c o r r e ct l y b e l o n g t o t he s p e c t r u m o f R A .

The ARA c lass i f i ca t ion schemes , however, do no t p rec lude the iden t i f i -c a t io n o f s u b g r o u p s o f R A . M i t ch e l l a n d F r i es ( 1 9 8 2 ) , fo r e x a m p l e , h a v eana ly sed the l i nkages be tween the 1958 ARA cr i t e r i a i n a c l in i c -basedse r i es o f 840 pa t i en ts ove r t he age o f 16 and iden ti f ied seven m ajo r c l in ica lsynd romes . More r ecen t ly Se l l i ck e t a l (1990 ) have a l so u sed non -h ie ra rch ica l c lu s t e r ana ly s is m ethods to examine the d i st r ibu t ion o f c lin i ca lf ea tu res amo ngs t cases c lass i fi ed as R A b y the 1987 c r it e ri a. T he i r meth odc lass i fi ed pa t ien t s i n to f ive g roups on the bas i s o f b iochem ica l and c l in i ca lvar iab les . The 1987 c lass i f ica t ion t ree i t se l f gave r i se to f ive d iscre te end

po in t s i n w h ich subse t s o f d i sease cou ld be c l ass i fi ed as RA (F igu re 1 ).O t h e r a u t h o r s h a v e a l s o r e c o g n i z e d d i f fe r e n t su b s e t s o f R A b a s e d o n t h epa t t e rn s o f d i sease p rog ress ion (Gordo n e t a l, 1973 ; Mas i e t a l, 1983 ;Pinc us and Cal lahan , 1994) .

Concern has been exp ressed tha t d i ff e ren t c r i t e r i a fo r case r ecogn i t ionare requ i red in d i fferen t se t t ings (Al lander, 1973; Edwards and Snai th ,1988 ; S i lman , 1988 ) . Th i s has bee n add ressed to an ex ten t i n the deve lop -m e n t o f t h e A R A c r it e ri a w h e r e a d i s ti n ct io n h a s b e e n d r a w n b e t w e e n c a s erecogn i t ion in the c l in i c and in popu la t ion samp les . The va l ida t ion s tud iesd i scussed above ind ica t e tha t t he 1987 ARA cr i t e r i a se t a re super io r t o

ex i s t ing c r i t e ri a se t s a s a metho d o f case r ecogn i t ion in the c l in i c . In popu -l a tion sam p les , t he 1987 c r i te r i a a l so pe r fo rm wel l in comp ar i son wi th them ore cu m ber som e Ne w Yo rk c ri te r ia , i f t hey a re spec i fi ca lly adap ted toinco rpo ra t e ev id ence o f pas t d i sease. I t is impor t an t t o s t ress , how ever, t ha tthe 1987 A R A cr i te r i a se t we re deve lo ped in pa t ien t s and con t ro l s r ec ru it edf rom a sam p le o f hosp i t a l c l in ic a t t ender s. Imp or t an t va r i a t ion in the


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300 A.J . MACGREGOR

sens i t iv i ty and spec i f ic i ty o f c r i t e r ia may there fo re occu r when thesecharac te r i s t i c s a re mea su re d in d i ff e ren t g roups .

O ne g roup , h igh l igh ted above , in w h ich the 1987 c r i te r ia pe r fo rm poor lyi s in cases o f ea r ly RA where the r ad io log ica l c r i t e r ion may be in su ff i -c ien t ly sens it ive . L ich tens te in and P incus (1991) hav e r ecen t ly show n tha tthe R F se ropos i t iv ity c r it e r ion m ay ha ve r ed uced sen s i tiv i ty in popu la t ions tud ies o f RA. A rev iew o f f ive c ross - sec t iona l popu la t ion s tud ies o f RAsho w ed the p reva lence o f RF in ind iv idua ls w ho sa t i s fied the 1958 c r i te r iafo r RA was subs tan t ia l ly lower than the 70 -90 % f igu re r epo r ted in hosp i ta lc l in ic -based s tud ies .

Po ten t ia l d i ff e renc es in the u t i li ty o f ind iv idua l c r i t e ria a re an im por tan tcons idera t ion in s tudy ing the e thn ic and geograph ica l va r ia t ion in theo ccu r r en ce o f RA . A h ig h b ack g r o u n d p r ev a l en ce o f RF h as b e en r ep o r t edin a nu m be r o f A f r ican and As ian popu la t ions (Abram son , 1967). A lowp r ev a l en ce o f RF h as b een r ep o r t ed i n c e r t a in A f r i can p a t i en t s w i th RA(Ad eba jo e t a l, 1993). Th e m orn ing s t if fness c r i te r ion has a l so been fo undto be a pa r t icu la r ly poo r d i sc r imina to r o f RA in Af r ican popu la t ions(Beighton e t a l , 1975; Adebajo , 1988) .

Th e r e l iab i l ity o f ind iv idua l c lass i f ica t ion c r it e r ia i s a fu r ther imp or tan ti s sue . In the deve lopmen t o f c r i t e r ia se t s , a t t en t ion has been g iven tos t an d a rd i za ti o n o f a s s ay s f o r s e r u m r h eu m a to id f acto r. T h e a s s e s s m en t o fr ad iog rap hs ha s a l so b een sub jec t to s tandard iza t ion (Lar sen e t a l , 1977).Desp i te th i s , impor tan t in te r-observer va r ia t ion in the in te rp re ta t ion o frad iog raph s is r ecog n ized to occu r (Ab rams on , 1967; W ood , 1970). W idein te r-obs erver and wi th in -pa t ien t va r ia tion has a l so been d oc um en ted in thec l in i ca l a s s e s s m en t o f m o r n in g s t i f f n e s s ( K e l lg r en an d L aw r en ce , 1 9 5 6 )and o f jo in t sw el l ing (O 'Su l l ivan e t a l, 1968).

In the 1987 A R A cr i teria , the re l iab i li ty of the ind iv id ual cr i ter ia base don c l in ica l observa t ion i s like ly to hav e been e nha nce d over p rev ious se t sb y in co r p o r a ti n g th e p a t te r n o f j o in t i n v o lv em en t an d b y r e s tr ic t in g t h enu m be r o f e l ig ib le jo in t a r eas to 14. The def in it ion o f sym m etr ica l jo in ti n v o lv em en t , h o w ev e r, co n tin u es to b e v e r y m u ch o p en to in t e rp r e ta t io n .

Th ere a l so r ema ins subs tan t ia l w i th in -pa t ien t va ria t ion in the m orn in g s t if f -ness cr i ter ion as def ined in the 1987 cr i ter ia se t (Haz es e t a l , 1994) .T h e s ea r ch to f i n d m o r e o b j ec t iv e m e th o d s f o r q u an t i f y in g c l i n i ca l

observa t ions in RA has a long h i s to ry. Sugges t ions such as the use o fdo lo r ime t ry in the qu an t i ta t ive app ra isa l o f jo in t t endernes s and r ad io -lo g i ca l a s s e s s m en t f o r m eas u r e m en t o f s w e l l in g ( A b r am s o n , 1 9 67 ) h av eno t fou nd a p lace in c lass i fica tion . More r ecen t ly, how eve r, p rac t ica l m od i -f ica tions have be en p ro posed to the c r i t e r ia fo r jo in t sw el l ing and m orn in gs t i ffness (Rigby and W ood , 1991; H azes e t al , 1993) w h ich m ay p rove tobe o f va lue an d m er i t fu r ther exp lo ra t ion .

T h e r e i s a l s o t h e h o p e th a t s e r o lo g ica l an d g en e t i c m a r k e r s o f d is ea s em ay in the fu tu re p rov ide too ls fo r d i sease c lass i fica tion . As ye t , p rop osednew se ro log ica l marker s such as an t ike ra t in an t ibody and an t ipe r inuc lea rfac to r have n o t p rove d to be a l te rna t ives to RF (yon Essen e t a l, 1993). Th er e s u l t s o f im m u n o g en e t i c s tu d i e s a r e , h o w ev e r, m o r e p r o m is in g a s t h eassoc ia t ion be tw een R A and gen es enco d ing c lass I I an t igens is c la r if ied


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C L A S S | F I C AT I O N C R I T E R I A F OR R A 3 0 1

(Gre ger so n e t a l, 1987; W ey an d e t a l, 1992). Re cen t s tud ies have show n a200- fo ld inc reased r i sk o f RA in ce r ta in gene t ica l ly def ined subgroups(Ol l ie r e t a l, 1993). Th is m agn i tud e o f as soc ia t ion , w h ich approach es thes t ren g th o f th e a s s o c ia t io n b e tw een H L A - B2 7 an d an k y lo s in g s p o n d yl it is(Brewer ton e t a l , 1973) , may ass is t d isease c lass i f ica t ion in cer ta in sub-g roups . Fa m i ly da ta on R A m ay a l so in the fu tu re con t r ibu te to c lass i fica -t ion (W alk er e t a l, 1987).

Class i fica tion m ethods fo r RA wi l l r equ i re con t inua l reappra i sa l a s thec l in i ca l co n cep t o f t h e d i s ea s e ev o lv e s an d a s g r ea t e r k n o w led g e o f a e ti o -log ica l m ech an is m s deve lop . Fo r the p resen t , how ever, the 1987 c r i te r ia se tb e s t r e f le c t t h e cu r r en t u n d e r s t an d in g o f RA an d p r o v id e t h e m o s t ap p r o -p r ia te bas i s fo r case r ec ogn i t ion o f es tab l ished d i sease bo th in the c lin ic andin the pop u la t ion .

S U M M A R Y

T h e d ev e lo p m en t o f c la s s if ic a ti o n s ch em es f o r RA in t h e l a s t 4 0 y ea r s h a sf o l lo w ed th e i n c r ea s in g ly p r ec is e u n d e r s tan d in g o f t h e n a tu r e o f t h e c l in i ca ld i sease and the r ecogn i t ion o f the d i ff e ren t r equ i r emen ts o f c lass i f ica t ionm etho ds in c l in ic and popu la t ion se tt ings .

In pub l i shed s tud ies o f RA in c l in ic pa tien ts the m os t w ide ly used c r i t e r iase ts have been the 1958 A R A (A CR) c r i te r ia and i ts 1961 adap ta tion ( theRome (act ive) cr i ter ia) . These se ts c lass i f ied d isease as 'c lass ical ' ,' d e f in i te ' , ' p ro bab le ' and 'poss ib le ' RA based on c r i t e ria com pr is ingcl in ical , sero logical , rad io logical and h is to logical fea tures ( the la t ter wered r o p p ed f r o m th e R o m e c r i te r i a s et b ecau s e o f t h e ir im p r ac ti c a li ty ) . M o r erecen t ly, a new cr i te ria se t (the 1987 A R A cr ite ria ) has be en de ve lop edus ing s ta ti s ti ca l techn iques . Th is se t was der ived us ing R A cases andcon tro ls a t ten ding h ospi ta l c l in ics . I t i s based on the ear l ier cr i ter ia se ts bu tacco m m o d a te s t h e ch a r act e ri s ti c pa t te r n o f j o in t i n v o lv em en t i n RA m o r ep rec ise ly. The c r i t e r ia r ecogn ize on ly the s ing le d i sease ca tego ry o f

' rheumato id ar thr i t is ' . In val idat ion s tud ies , the 1987 cr i ter ia se t has beenfound to have enhanced spec i f ic i ty over ea r l ie r schemes in c l in ic -baseds tud ies o f RA. The sens i t iv i ty may, however, be r educed , in par t icu la r ins tud ies o f ea r ly d i sease .

The app l ica t ion o f c lass i f ica t ion c r i t e r ia fo r case r ecogn i t ion in thep o p u la ti o n an d f am i ly s tu d i es o f RA h as p r o v ed m o r e p r o b lem a t i c. I n t h e s ese t tings , the re i s the ad d i t iona l r equ i r em en t to r eco gn ize ind iv idua ls w i threm i t ted and inac t ive d i sease as RA cases . The 1966 Ne w Y ork c r i t e riaw e r e d ev e lo p ed f o r t h i s s p ec i f i c p u r p o s e , h o w ev e r t h e i r f o r m a t p r o v edcu m b er s o m e an d th ey h av e n o t b een w id e ly ad o p ted . T h e 1 98 7 c r i te r ia s e t

i s in su ff ic ien t ly sens i t ive to r ecogn ize inac t ive d i sease i f the c r i t e r ia a reapp l ied exac t ly as they have been def ined . The sens i t iv i ty o f the 1987cr i te r ia se t i s, how eve r, subs tan t ia l ly e nha nce d i f the c r i te r ia a re adap ted toinco rpora te f ea tu res o f pas t d i sease ac t iv i ty, fo r example by a l lowingde fo rm i ty to subs t i tu te fo r swel l ing and by inco rpo ra t ing da ta on the pas to ccu r r en ce o f r h eu m a to id f ac to r an d r h eu m a to id n o d u le s.


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D e v e l o p m e n t s i n t h e i m m u n o l o g y a nd g e n e t i c s o f R A m a y i n t h e f u tu r ep rov ide more accura t e t oo l s f o r c l a s s i f i ca t i on and may l ead t o r ecogn i t i ono f m o r e p r e c i s e d i s e a s e s u b s e t s . A t p r e s e n t , h o w e v e r, t h e 1 9 8 7 A R A

cr i te r ia pro vide the m os t appropriate bas i s for case reco gni t ion in bothc l i n i c and popu l a t i on -based s t ud i e s .

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Art 30 Criterii RA