Development and reliability of a system, to classiffy gross motor function in children with cerebral palsy

L Itobrrt Ai1i .w t i o Ie fe r Hose tiOri ii t t t Sfepl ie t i Iliiltrr Diii it iic I! i i ssc 11 Ellor ilbotl Hn r h rii (hi 1 ii p p i

To address the need for a standardized system to classifs the gross motor function of children with cerebral palsy, the authors developed a 5vvelevel classification system analogous to the staging and grading systems used in medicine. Nominal group process and Delphi survey consensus methods were used to examine content validits and revise the classification system until consensus among 48 experts (physical therapists, occupational therapists, and developmental pediatricians with expertise in cerebral palsy 1 was achieved. Interrater reliability ( K) was 0.55 for children less than 2 years of age and 0.75 for children 2 to 12 years of age. The classification system has application for clinical practice, research, teaching, and administration.

(erebra1 palsy irfcrs t o a group of disorders in the tlevelop- iiicliit of posttrire a i d motor contid. occui-i*ing as a result of a noii-progressive lesion of the developing cent rid ner\ous s p - ten1 ( U n s 1964).This tletinit ion ent-ompasses a witle vaiiety of pithological and clinical entities that have i n common atlevel- ol)inentaI iiiotoi-disorder that can viwy in etiology, manifesta- t ions. stverit.y. prognosis. antl comorbitlities. Despite the best efforts of I)rofcssionaIs.fi.oiii many disciplines, a gieat deal iwntiins unknown about the na turd liistoiy of cerebral palsy. I t is iwognizetl that motor oiiteome is i.oughly ielatetl to severity but to (late there has not been a genei*ally accepted stantlartlizetl system of classification of severity of motor tlis- ability for use i n clinical practice antl research.

M e t hods of classification that have been proposed are biisetl on ( a ) pathophysiology o r neui.oanatomical location of

tIw lesion (Fay IO:TO, Perlstein 1957, Minear IN6):(b) impair- ments in iiiuyle tone. refles activity. and voluntary control of movc~m(wt (Fay 1950, Perlstein 1952): (c) parts of the body most involved (Balf and Ingram 1955, AIincar 1956): ( ( I ) ambulatory status (Ratlell-Ribcra 1985.Yokochi et HI. 1993), tir (e) cl~grec of motor impailmcnt (e.g. mild. moderate. severe) (Balf aii t l Ingrain 1955. hliiiear 1966, Yokoclii et al. 1!)!):3).Ihese incthotls of classifiration rely heavily on clinical j utlgment antl are primal-ily of value for tliagnosis.Th(4r relia- bility antl validity have not been investigated. Evans et al. ( 1989) tlevelopetl 11 recording forin to collect data on impair- ment niid disability i n children with neuroniotor dysfunction for use i n a register on childhood impairment. The form indutles items to rate a rhiltls head control, trunk control, gait ,and upper limb fnnction but does not inclutlc an o v e i d classi tication of motor ability.

\Ve have a t lop td an alternative approach to classification, basetI on the concepts oftIisabiIity and h!!ctiOnaI limitation. The International Classification of Impairments, Disabilities, and Hantlica~k (ICIDH) developed by the World Health Organimtion ( 1980) defines disability as the restriction or ladr of ability to perform an activity i n the manner or within tlir range consicleirtl normal for a human being. The concept of functional limitation is includctl in the models of tlisable- inent tlcvelol)etl by Sagi (1965) and the Sational Center for - Jiedical Rehabilitation IkwwcIi in the United States ( 1993). Sagi defiiiecl functional limitation as a limitation i n perfor- mance at the level of the whole person. We believe that classifi- eation of children with cerebral palsy on the basis of abilities antl limitations in gross motor function should eilliance com- munication among ~irofessionals antl families with respect to ( 1 ) tletcimining LI chiltls needs antl making management dcci- sions. (2) the creation of databases describing the development of ehildien with cerebral palsy, and (3) comparing and general- izing the results of program evaluations and research into the outcome of treatment. Furthermore if the classification sys- teni is found to have predictive validity, early classification of a child (e.g. at age2 years) would help parents to anticipate their cliiltls later motor function.

The purposes of this study were (1) t o construct a gross motor function classification system for children with cerebral palsy, annlogous to the staging antl grading systems used for tumours, (2) t o esamine content validity through nominal group process and Delphisurvey consensus methods involving tlevelopmental therapists and pediatricians with expertise in cerebral palsy, and (3) to determine interrater reliability of the classification system. We wanted a descriptive classification

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system that \voultl be quick iintl easy to use. valid, and I-eliable.

Method The Gross Motor Disability ('Iassification System was tlcvrl- oped i n four 1)hiiscs. First the autliors tlraftetl tlie system. During phases two and tliive. the validity of the c-ontrnt WIS esaminecl using nominal group process antl Delphi survey coiiseiisus nietliotls, ant1 tlie c.liissifi,c;ltioii system nw revisrtl. Iiiteri-ater reliability was esiiininetl in phiisr four.

I) E V E 1.0 IA m r ( ) P T ti I.: ( 'IASSI 1w-m I os sss'r EM The classification system was initially tlraftetl usin$ sevtwl methods ofinc(iiii.~~.Tliese inclutlrtl a review ofcsisting rlassifi- cation systems and reseaidi on tlevelo~~mrnt (if cliiltl~*eii with cerebral I'alsy:esaminatioii oftlata from 275 chiltlrcn to wliorn tlie Cross Motor Function JIeasuir: ((3IFJI) (I

ulai-ly in thesroresof rhiltlren classifictl as having motleixteor severe cerebral palsy. After escimining the C A I FA1 data antl viewing ttic videotapes. we tlecidetl that a three-level classifi- cation system (lid not atlequately represeiit the variation i i i gross iiiotordr\~eIopnieiit of cMtlirw with ~*ei-ebraI ~):ilsp

Ev~ntually it five-lcvel &ssi tication SysteIiI \WS ptap~~ed iv1iic.h i n the autl1ars'ol)iiiion iq)resentetl clinically meaning- f d distiiwtions in motor function. I n beping with the World Health Organization> const r w t oftlisiibilitp we iociisetl the classification syst6ni on self-initiated movement. with empha- sis 011 function i n sitting and \valking. 1)istinctioiis hctwerii Irvels fociisetl on fiinctioiial liniit$ ions, the need hr. assistiw technology inclutling mobility devices (such as n.alkers. criitrhes. and canvs). wlieeletl iiioldity. and to a lesser extent quality of Inovcment. The system is ordinal. with no intivit that the distance betwen levels be coiisitlrretl eqtial or that chilthvn with cei.ebi-al palsy urct~~~iial i~t l ist i~i l~ute~larnoi ig the five 1evels.Thr rliissitiwtioii system was iiitcntlctl for use with chiltlrvn 18 months to 6 p a r s of age. I n keeping with the goal that tlieclassiticatioiis~steiii be cpiclc andeasyto usebasedon Wported 01' Observed glnSs I l l o t o ~ fUlIrtiol1 I'ilthPI' thHJ1 011 stanrlartlizetl testing. brief tlesc~iptions were piwitled for each level as \veil as a somimiry of the rlistinc*tions betweeii each pair of levels. The rlesrriptions weir broiltl and \VPIT not intent~et~ to assess iii (letail t.iie tlevelopineiit ofintlivitiual ciiil- tlien but rat hcr to tleterniine \vhic:h of t he five levth most dose- ~y resL'nibIes a ciiiItIs c*iri~r~nt gi-o,ks motor firnrtioii.

S O Y I S A I . (;KoL-l' I'KO('E:SS

IJI phase two. content v;rliOity was examinetl using a modified nominal group consensus mctliotl. Sominal group ~)rocess consists of a structured meeting of il kno\vletl~able target group in which issiies are clisc*ussecl among piwticipants i n an attempt to Iri\ch a coi1seiisiis (Fink et HI. 1'384).TIic procedure was modified. in that the first draft oftlie classification system \vas developed by tlie riuthoi.s witlioiit input from the target group.The initial draft oftlieclassification system antl a C~UPS- tionnaire were sent to occ.upntional therapists antl physical therapists at tliirr rliiltlivn's treatment centres in soutlierii Ontario 3 weeks before the consens~~s meeting. Twenty-eight therapists provided feedback on the mntent antl on tlie applicability o f t he classification systeni to cIiiIclren on t Iieir caseloaJ. Of the 28 participants. 14 were occupational theru- pists and 14 were physical therapists. The therapists' clinieal experience rangxl from 5 to 3Oyears, with a mean ofn.6.

Representatives from each ofthe three centres brought the feedback from their centre ant l partieipatetl in tlie consensus meeting. I n total, 13 therapists antl two developmental pedia- t ricians were voting part icipants in a half-(lay consensus escr- cise. The eselrise started with an open discussion by participants of their general inipirssions of the classification system and the process used to accumulate the feedback from tlieircentre.The group then proreeclecl to respond to 17 state- ments. One member ofthestudy train chaired thesession, two served as tlisrussants. H i i d a fourth member served as rwonler/timcr. The discussant introtlucetl each preset statc- nient antl then facilitated discussion among the participants. The statements atltlivssetl the applicability of the classifica- tionsystem, how thesysteni$houltl beadministeretl, thenurn- ber of levels. the content of each level, distinctions between levels, antl the ages of chiltli-eii who coulcl be classified. When the time limit for discussion of each statement was rrac*hetl,

216 I ~ ~ ~ P ~ ~ I ~ I ~ I I P I ~ ~ I : ~ , ~ / P ~ / ~ ~ ~ I ~ ~ cp ( 7 i i l d . ~ ~ t i r o l o ~ ~ y 199i , :39: 214-228

the ('hair took a formal vote. The participants were asltetl to approvenr mjec-t eiwh stateinent. Forriirh statement, tlie con- sensus target speci fietl i n atlviince was approval by at least 12 oft he 13 prticipants..

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I)EI.I'HI S('l{\'lCY Tlir Delphi conselisus met hod is an attempt to obtain espei:t opinion i n H systematic 1iiil1111er through qiiestionnaires. with the ultimate goal of generating a group response (Fink et al. 1!)84).'l'he xrii.\~y is contluctetl ovcr two or more rounds. After eiieh round. the panel of experts is informed of the results. ivhirli iwe t1it.n usrtl to construct tlie cliiestioiiiiaii~fortlie nest iwuntl.'I'lir process ends when the group reaches a preset level of agreeiiient or . \vhen sufficient infoixiation has been rschangecl to achieve t he goals oft he process.

I n selecting a panel \IT cc)nsidered the rec.oniinentlations of Fink ct nl. (Ins$). who stated that coiisensiis pal-ticipants shodtl Iiave c*oiitrnt esiicrtise. be iq)rwentativo of t heir pro- fessioiis. and hiivc the ability to implement findings. In acltli- tion. we selectetl participants who we thought \voolrl provicle insightfid antl critiral input antl advice. Twenty-one pliysical theixpists, occupational therapists. antl clcvelopnicntal petlia- tiicians from Sorth r\nierica. Europe. and Australia were nskctl to participate and PO agreed (Appendis .A).The partici- pants were recognized Ieatleisintlie fieldoftlevelopmental dis- ability with espertise in ceiybral palsy. Sone of tlie persons selected had participated in the nominal group consensus meeting. The yei1l.s of professional esl)erience of the panel nicnibers varied from (i to 38 yeais, with 11 nieilli of2O years.

The qiiestionnaii~e for round one of the Delphi survqy was clivitlecl into three parts antl includctl 38 statements. Many statements were followed by an open-ended question t o encoui-age the experts to elaborate upon their responses. Part A coiisistetl of nine statementsthgt acltlressetl the need for antl thc c-onstrurt of the classification system. Part B consisted of 23 stateinelits that atltli~essed the definition antl description for each of the five levels and the tlistiiictioiis between levels. The experts were asked to use the clawification system to clas- sify the mofor fiinrtion of rhilclirn from their clinical practice. Those who did use it completed Part C'. which inrludcd a state- ment on the ease of using the c~lassification system antl invited coniments. Part D consisted of five statements aclclrrssing potential uses of the classification system.

Each statement was rated using a seven-point scale, with t i rating of I inrliyating 'strong disagreement'. 4 indicating

.. 'indiffeirnce', antl 7 indicating 'strong agreement' with the statement. Before mailing the questionnaires, consensiis agirement for each item was defined as 16 or more of the 20 esperts rating the statement as 5 or higher. Each participant was mailed the questionnaire for round one of the Delphi sur- vey the revised (hoss Motor Function Classification System, an explanation of why tile classification system was being clevelo1)etl. and the work to date on development oftlie classifi- cation system.

The questionnaire for round two included 28 statements. The 23 statements from Part B o f the questionnaire used in round one weit i.epeatcd.Tliese statements addressed the tlefi- nition and description for each of the five levels and the distinc- tions between the levels. The reinaining five statements addressed how the classification system should be adminis- teird and the ages of chiltlren who could be accurately classi- fied. These were areas where conknsus was not achieved in

ro~uicl one. .4long with thv cluestioiinaire for round two of tlir Delphi survey the esprrts \vei*c also mailed the rwisetl (~i*oss Motor Function C'lassificiition Systeni, a siinimary of the

conipletetl questionnai re froin 1.ouiitl01i(~.

I S'I'EII l?.\Tk;II I< l~:I,IA Is1 1,I'I'Y Interratcv reliability \fils rxiuninetl iifter i * o i ~ ~ i t l two of tiit> Delphi sur*\yv was coniplrtetl. iintl the finiil irvisions \vere niatle to the classification system. A con\~enieiicrsiiiii~~lr oftivr Ailtlren's tiwatment centres in southern Ontitrio participated i n the stutly Physical tlieixpists iiiitl occupatioiial theriipists tit the five centres WCIP iisketl to compile i~ list of chiltlren 12 years of' ~ g e or younger with cliiignosetl or suslwdrtl c e i v l d ~)alsy.TIie chiltlren inclutletl on t lie list n ~ r c on act iw i~iiscloatls (seen within the past 6 months) iintl had been known to at lrast two tlie~~apists for at least 3montlis.l'hc~ lists were tlivitletl into

Seventy-seven chiltli~eii (37 i n the youngw age group and 40 in the oltlei~agegi~orrp) \rere i~iintloinly selected from the lists i)ro- vitletl b.v the thrrapists. with the specificiltioli tlliit 110 pair of therapists woultl classitjl inore tliiin five cliildrrn.

Etdi chiltlk level of gross motor fiiiiction \vas classi tirtl int1el)eiitlently hy two therapists who WIP fhIi1ilii\r with t hc rhiltl. Twenty-six p11ysic.id tlicrapists aiitl 25 occ.ul)atioii;il tlwapists paiticipatetl. 'l'lie thcl~iipists' years of cqwiciicv varied from 3 monthsto :%I years (niean 10.2 years).'rhc thcra- pists relied on their lano\vletlge of the child's motor abilities to classitj the child's level of gims motor function and \ v t w not rwiuiretl to obscrve or assess each child. Once the thei.apists hiit1 familiarized theniselves with the cl;issific.ation system. the time required to classifk a child shoultl not have csceedetl 10 minutes.

Interrater reliability was analyzed scliaratrly for cadi tige groui) usiiig the crutle p(weiitiigc ofngi~e~nient and the k i i p p i ~ ( K) statistic, a measure of cliiiiic~c-c~ori.e~~tetl agreement. I n atldition to the overall level of chance-corwctctl agreenient. category-specific K VHILWS tlerived to determine chancr- corrected agreement on each of tlie fivr levels of tlic classiti(-ti- tioii system. ('ategory associations were evaluated by compiitiiig the contlitional probabilities that givrii that one rantlomly selcctetl therapist chooses a particular level of fiinc- tion. the second therapist will choose rarh of the five levrls of fu nrt ion.

responses from r m n t l onr oft liesurvcy. and a c*opy oft h c ' i l'o\vn

t\\vo age Striiti1: untler 2 J'WI*S o f age ~ I K I 2 JYYII'S 01' o l t l ~

Results SOlIISAI, (:lIoL*I' I'HO('ESS

Consensus or approval of a statement by at least 12 of the 15 voting participants was reached for 13 ofthe 17 stateinents. All of the paltiripants rejected two of the statements: ' T ~ c classification system is sufficirnt to iclii~sent the variation i n motor ;lisiibility among children with cerebral palsy':and'Thc system should focus on best ever performance.'Oiily 11 of the 15 voting partic*ipants approved the statement'tl child ciin be classi tied accurately from a parent/caregiver irport using a structured iiitei.view.'Only 10 approved the statement that 18 months should be the lower age limit for the classification sys- tem, antl only five approved the statement that 12 months should be tlie lower age limit for the classification system. Based on discussion among the participants of the statements where consensus was not achieved, the descriptions for each level ofgross motor function and tlie distinctions between lev-

Table I Statements for which the 20 experts did not reach consensus after round one of the Delphi survey

rately cliissitied I)iisecl o i i ii j)roft~asioiiiiIs f:iiiiiIiarity with tlie cliilrl over a lieriot1 of :it leost 3 inoiit 11s. only I:! of 20 o'f' t lip experts :tgiwI tliat tlie e1assific;itiim systeiii coiiltl he iisecl fbr itif~int?;as.?.oiiiigiis I2 iiiont Iisnfap.

-411 oft lit. es1;wts iiitliciitetl t hiit ;t cI;irsification systeiii for cl i i l t l irn it11 c.erel)riil lialsy has applicatioiis for i-esc.iiri.li aiid te;wIiiiig. Siiirtwii of the 20 esprts iiidiviited tliiit it Iiiw &~iciitimi for c~iiiicii~ prac.tice. I i iii(~ic;ite(~ t ~xit it ~iiis iipp~i- cation fc)rntIiiiinist ration. ;\nd 13 intlicatrtl that it 1insiilq)lica- tion forsports particip n t ' 1011.

Eleven of the 20 eslierts iiscd tlie system to cliissifv tlir motor functiln of betueen 2 ;inti I ( j c . ~ i j ~ t ~ r w i wit11 iwe~wii~ piilsy .-\I1 1 1 i q e r t s intlicatetl that they found the c*lassificii-

- tion system easy to nsr.Tlie system \\as iyvistd a sec.ontl time based on t IieirsiiItsofthe 1 h l 1 ) h i survey and tiicesperts'\\ rit- ten cominrnts.

For rouiitl two oftl iesui~i~y. c.oml)lctetl c~~i~~st ioi i i i~i i~es ivew received f i m i 18 of tlic 20 rspwts. ('onscnsIis amoiig thi. 18 chxpelts \\:is achievetl f ~ l ~ i l l l 2!!)sti~tc11ir1its.;\II 18 oftlie e s p * t s ~1gi.ertl with 1.5 of the statrinrnts arid Ii agiwrl with 11 ofthr stiitenieiits. Sisteen of tlie expiBrts iqyrcd with the statement tlriit tllcc.l;issitici\tio~l system c~oultlbeiic.rurtitcly iiscd forcliil- tlren 1 to 2yeiiisofage. Fiftrrn iigrectl that tin ii~*c*tll~iitr (*Iassi- tication cwultl he niiltle froin ii st ructii~~etl interview with a parent oi*caiq$w. Siiicoftlic2Oc\-l)erts usrtl tlie iwisctlsys- tein to eltissify thrniotor fiiiii~tioii oil)et\vecn 3 tint1 16 chiltliwi with cerebixl ~)aIsy..411 niiir e s ~ ) w t s intlic*iitrtl tlittt they f i y i t l the system easy to use. Based on the r x p t ~ t s ' w~itteq-c!oin- nients. irvisions \\ere niacie to ciiirif\. some of t ~ i e tlcfinitions atid tl~sc*ril)tioiis. The ci i r i~nt version of the (:i*oss Alotor Function C'las~ific.ntioii System is iii.\p~ieiidis B.

I STE I< I{ XTER II E 1.1 .\ 111 LIT s Tdble I 1 lists tlie tlistribution of tigr~ennents and tlisagrec: iiients aiiigng the five Ievrls ofthe i*lu~sifi~i\tioii system by age group. OCertill. tlir ratings \vci*e fkirly evenly tlisti~ibutecl aniong tlie five Ievc~ls. For tlie Xi (~l i i ldi~n less thaii 2 years of age. paired therapists agreed on the level of gross motor fiinc- tion for%. tlisitgiretl l)y one Ie\d for 11. ant1 tlisagrwtl bay two levels for 2. Of these 1.7 tlisagrc~enients. 4 wi'e I)et\veeii Levels I\' and 1: tiiitl 1 \vas betwren Levels I1 I ant1 \! For the 40 rhil- clreti 2 to I:! yenrs of age, 1)air~tl therapists tlisagretd by one 1 ~ ~ 1 fol.oiily 8:ofthese t l i ~ i i g ~ ' e ~ ~ i i ~ ~ i t s , 5 \vei'r between 1,evclu I and I I .

Tlir K coefficient is ii st~uitlartl agreement statistic usetl to correct for clinnce apreeineiit. For c. l i i l t l iw uiitler 2 years of

Table ll Percentages of agreement and disagreement between paired therapists for each level of the classification system, by age

age. K was 0.55 \vliile for c l i i ldi~~i 2 years of age or oltler- K was 0.75.TIie irsiilts 1)rovitle iiiotlei.atesii~~~~ort fortheoverall i r l i - ability of the ctiissiticiition system. I t lias been suggested tliat ralurs of' K ,nir;iter t lian 0.i5 IPI ) IPWII~ excellent agiwinent I)eyontl cliance. and \-;ilues i n t lie range 0.40 to 0.75 irpresent fiiir to good agiremeiit beyond clioiice (Fleiss 19SI).

-4ssociation and agirenient statistics tliat aiialym inter: riitcr reliability for eiic.11 of the tive IcveIs of the cIa.ssification systeni 1)y agegroup are p~~sented iiiTables 1 I1 ant1 I\: resl)rc- tively I n both a p gir)iip. tlir 1)roj)ortioii oftlie total number of classiticatioiis matle was ~rasonal)l.~ evenly t1istril)uted over t lie five ~evels. or c~iil t~irn untler 2 years of age. t ~ i e K eoefti- cirnts (Table I I I ) indicate better chance-cori~ctetl agreement for Levels I and I 1 than fortlie other t h iw levels. For instance the K f o r Level 1 is 0.841. iiic~ic~atiiigcsc~e~lent tlistiiiguishabili- ty of Level 1 froin tlie others. whereas that fQr Level \: is only 0.368. iiitlicoting tliat Levc.1 \' is nioir often conftisctl with the otIiri*le\~ls.

The category association statistics (Table I V ) indicate that foi*cIiiltlirn underage2 theassoriation betweeii tlieclassifica- tions oftlir paired therapists \ViiS ptirticularly strong for Lev- els I nntl J I.'rliat is. if the first observer selected Level I. tliere W ~ I S ail 88% chu1c.e thilt the ~ e t ~ i t l observer \voiiltl a p e . I n contrast. tlisagreement I)et\veeii paired therapists \vas higher for the otlier levels, esperially for Levels IV antl L! which t i i t ninre tIiffic.uk to tlistinguisli from each other i n the younger age gi*orip. For example. i f Level \I was chosen by the first observer. tlierr wasonly a4494 chance that thesecontl obsery er*\vouIt~ agree. witli tIir tiiscortlant ratings being pritiiari~fat L e ~ l I\' (44% chance) 0 1 ' oc~i i~io~ial ly at Level I 1 1 ( 1 I % chance).

For cliiltlren above the age of 2 years, tlie patterns ively: soinrnhat reversed (Table lII).The K coefficients were highest (all ahow 0.8) for Levcls JII to c! while agr-eement on Levels I ant1 I1 was poorei: The association statistics (Table IV) intli- cate some tlifficdty in tlistinguisliing between k v e l s I ant1 11. \\'lien Level l o r I 1 mas chosen by the first observer, thesecontl obserrer agreed only 67 '% antl 53% of the time respectively. There was: Iionrvrr, clear tlistinc*tion of Lcvrls I ant1 11 from the other levels:tlisa,areeineiit above and b c l o ~ the Level-I I to IAevel-l 11 bound~ry was rieverobscrve.tl.Tliei~e was only minor tlisagi*cenient in tlisti~iguishingamon~ Levels I11 toVThesec- ontl observer agreed 92,87, aiid 89% oftlie time for categories I I I. I\! antl V respectively: tlie disagreements always con- cerrietl adjacent categories.

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t ! .r

; group

Discussion c;iven the complex antl variaidr IiiitllIP of the niovenieiit disor- ders i n cliiltlren wit 11 cerebral palsy. we believe that consensiis among a tliveiuc group of experts is an essential step in tlie develoimient of a valid elassi ticaltion system antl siibscqueiit iiw oftlir system i n clinic.al practice i d irsrarc.Ii.Tlie results of the nominal group process and Delphi survey coiiseiisus methods provide evitlencc of the validity of tlie content oft he Gross Notor Fuiictioii Classification System.Tlie inteniatioii- al group of experts \\-ere unatiinious iii their agreement that there isa need fora classification system for children \\-it 11 ceir- bra1 palsy that is 1)asetl on tlieconstruct ofdisability and fiinc- tional liniitiition. Although the experts initially espirssed sonie differences ofopinion regaiding the (Iewriptioii for each level, the distinction between each level. anti the iige of rliil- clreii who rould be classified reliably. consensus agreement I\ as ac*hievetl for all 2!J statements after two rouiitls of the Delphi survey

The ovei~all level of c1iaiic.c-coi~rectetl agreement ( 1 ~ 0 . 7 5 ) supports the interi-ater reliiibility of the classification system when usctl to classify the gross motor fiinc-tion of rhildren 1 to 12years ofagr. ~ i i r g o a ~ was to t~evc~op a c~assih'catioAs~stclll that is qiiick antl easy to use.Therefore. to examine reliability the thei*apists i.ec-eiwtl no special training antl ~vei-c not iwluirrtl to perform any iiSSeSSliielit proceclurea. Ratllel: each rljild's gross motor function \\-as inclrpcntlentlg classified by two therapists who weir familiar with the child's current

Table IIE Chance-corrected interrater agreement ( K) for each level of classification, by age of patients

I 0.216 0.841 o.w 0.3!)0 11 0.270 0.389 0.138 0.473 111 o. in9 K4iI 0.163 0.908 I\' 0.203 0.413 0 . m 0.817 Y 0.1"" 0 I?? 0.L'L.i 0.8.5i

motor al)ilities.Tlie i-esults sugvst that gross motor function can lie classi tied arcurately by occupat ional t lierapists ant1 physical therapists who have knowledge of a diildk current motor abilities.

Written roninients by tlierapists \die participated in the iPlialdity phase oftliestutly suggvst that interrater reIiaI)iIity \voultl Iiave hwn higher liacl tlie t herapists received formal ari- entation or training in the use of the classiticatidii system. 1lan.v of tlie questions that were raised could easily haw been atltlressrtl in a single training session. These indude concerns allout c.Iassif?.ing a child's motor function at a particular level if eitlirr quality of movement \\'as poor or the therapist 1)eIieved t he child's fiinction \vould eventually be classified at a higher level. Altliough the written instructions state that gross motor fiinrtion slioultl be clasbified based on the cliiltl's usual performance in Iionie. srliool. and community settings. some therapists esl)iws"eI iiiirc~rtaialy &lit wlirther to classi[y on tlic biisis of what the child can (lo at their best versus what tlir cliild ortlinarily does. One tlieriipist provided a written tlesrription of a c-hilti's niotoi-abilities that cleiirly irl)irsentrd IAWI V yet rlassificd the rliilcl's motor function as Level 1V. ('oininents I).y other therapists also suggested that theiv WHS soinc I T ~ I I C ~ ~ ~ I I W to classi[y ii child i n the most seveiv (*ategorSy

\\'e have attempted to atltli~ess ;dl t1ie.w concerns i n tlie Inti*otluc*tioii and LJser Instructions guide that is distrilwteti with the ('lassification System. Severtheless. to avoid errors attributable to iiicoriwt interl)luetiltion of the guidelines, we irconiniend that users establish interrater rrliiibility befor-e rising the classification system for research. We also ~rw"i- J I N W ~ I thilt pi*ofessioiials \\.ho \\odi togethrr classifjr the ~ I W S S niotor fiinrtion of several c*liildren froni their c*asrloads intle- ~)entlently and discuss the results before using tlie c*lassifica- tion system i n c4inical practice.

;\lthough t l ~ WIISCIISIIS of the rsperts \\.as that the 01i1ssi ti- cation systibiii can bv usrtl to cblassify acwratcly the gross motor function of chiltlren between 1 iiiitl 2 years of age. roni- nients niatle by sonic oft he expvrts suggested that this may be cliffiriilt. Interrater reliability tlierefoix?, was csuniined sepal- ratrly forrhiltlren untler the~gc~of).yriirs.Tlic ovrrall lcvrl of

Table IRCategory association statistics for each level of classification, by age of patients

I o.n8 0.13 0.00 0.00 0.lM I 1 0.10 0.70 0.15 0.0.5 0.IM 111 0.00 0.2 1 0.5i 0.14 0.07 I\' 0.ou 0.07 0.13 0.33 0.27 v 0.00 0.00 0.1 1 0.44 0.44

I I 1 111 I\' \'

0.G7 0.33 0.00 0 . I H ) 0.00 0.45 0.55 .. 0.00 0.00 0.00 O.( I 0 O.lH) O.!PL 0.08 O . I l 0 0.00 O.(lO 0.04 0.8i O.O!) 0.00 0.00 0.00 0.1 1 0.89

Iironounced for cMtliyii iintler 2 years of age. Despite t lie esperts'concerns that the distiiwtioii between I,e\ds I and I I and between Levels 1 I1 aiitl I \' woiiltl be tlifticolt. the t hera- pistswlio participated in tlie idiability I)liascofttirstritlg had the most tlisagiwnients bt*t\veeii I ~ ~ w l s I\' and I! Until the idiiibiIity aiitl vditlity of the cl~i~sifi~~atioii system are esam- inetl fiirther. carit ion shaultl be eseivisetl whiw classifying t tic grossmotor function of c*liiltIiw iintlci-2 years of age.

Level I represents the c*ontinuum of chiltlirii with iieui'o- motor impairnirnts \vhose fiinc*tioniil liiiiitatioiis tuv less than what is often associated with cvri*l)ral piilsy and chiltlren \vho have traditionally berii tliagnosrtl as having *niinimnl brain tlysfunction' oi~*iwel)raI palsy of niiiiiniitl severity'. The con- struct for 1,evel I is consistent with the tintlings of ('oolman ant1 associaites ( 1985). \v~io rrporteti tilclt somc cIiiltIiwi born I)ii*tcriii tlemonstiatr a pittern of persistent nriii~omotor iibiiormalities that aw not iis s(ve1~1 ;is those assoc~iatctl with ccirbral 1 ) a h ~ \Ye ainticipited that the tIistinc*tion Lwtiverii Lrwls I antl I I \ \~oult l be tlie most tiifticult \vhen classifjring the motor function ofchildiwi untlcbi .2 yriii*s of age. its tliffrrwicrs i n mobility :LIP not 1)roiiounced. For the tlierapists who prticipatetl i n the idiability phase ot'tlie study. ho\\cvt*i: tlis- agrveincnts betiveen Levels I aiitl I I \ v t w moir frequont \\hen cliissif\.ing the motor fiinctioii ofcliiltlitvi 2 to 12 yccirs ofagr. This suggests that the tlieixpists had difficdty deciding \vlwther ii child liiitl fiinctional limitations in the ability to a.alk outtloors antl climb stairs and \vhether a child can per- form gross motor skills such as runningantl juniping.

The therapists antl petliatric*ians who participatetl i n the nominal group process and Delphi siirvty consensus met hods iiitlicatetl that a t4assification system f(z. chiltlrrn with ccw- brat palsy hiis applic.iltiolls for clinical practice. research, teaching.' antl atlmiiiistration. I'articipants i n the nominal gr-oup process suggested that a classification system \ \ o i i l t l Iidp professionals to pwsrnt informetion on a cliilrlb current fiinctional a1)ilitics iintl assist f;milies and pi~ofessionals iu planning for a c*hiltl's iieetls. in(*lii(iing tlie recommended use of assistive technologp Part icipants also intlic.atcd t liat n classifi- cation system would be helpfill i n coiisitlering whethei- u child would benefit from specitic treat inciits. iiicluding surgical interrentions. antl i n providing misistency i n teriniiiology in the tlissemination of the results of tiwitment outcome research. Recommentletl atlininist rative appliriations of a i h s - sification system included the ability to tlisti-ibute the case- loiicls antl to tleteriiiine the irsniirces neetled for particuliir caseloatls.

An interesting philosophic*al issue has becw raised co;icern- ing the use of nunierical tlesigniitions for the tive levels oftlie classification system. rather than verbal rlescril)tors such ss 'miltl':motl~~rate'. antl.wveiv~. \Ye conclutletl that on balance the use of numbers to distinguish levels cwrietl less implied value than for esainple the terms just ~nentionetl. \Vc assunie that rlinicians coiinsrling piirents about a diild-s f ~ ~ i c t i o ~ i i d classification. i n this or any other system. will always spend time interpreting the meaning of each level. whether~it be a number or a tleseriptive trim. Furt1ierinoi.e. it might lie argued that words l ike~~e \~~~e '~~ote i i t ia l ly carry far mow emo- tional impart than a numerical designation. offered with mi explanation of the progiiostic antl clinical implicatioiis for that child.

Further research is aimed a t esaminiiig thr validity antl applicationx of the (:rims Notor Fuiiction C'lassifiratioii

System. The system is being used 11s the major stratification variablr i n a prospwtive longitutliiinl st utly of the tlevelop- inent of gross motor fiinction i n chiltli*eii with cerebral palsy. tlebigiirtl to ciPate'iiic~toi.gi~o\vtli curves'of't he motor progress of ii r;intlonily selrctetl cohort of cliiltlreii H(*I*OSS Ontario. \\% are ;dso untIei*takiiig a miislid retrospcc-tivr c-liart itview of ittlolcscents with ceid)ral palsy followtd I)rospei+tively from inftincy to assess how ncll chiltlrcn trark i n thesamec*liissi ticit- tion level, aii t l at what age their cliishitic-ation is predictive of niotor fiiii(*tion status at iige 12. \\'oi~lc is nntler way to assess the validity of' a bricf' st iwtuiwl inteiavicw with a parent. using algorithms t hat appear on pilot testing to Iiiivc. utility as 11 simple meiins of classifying c4iiltlren's gross motor function. I f t tic system proves as usefirI*as we IwIieve it to be. clinicians may for the first time have objective data to atltlress t l i c tno ni i l jo l . cluestions iislwtl by every parent ofa child with c.ercl)ral palsy:'How 1)ad is i t? ' antl '\\ 'hat i s ' the outlook {'or my cli i Id ! '

Appendix A:

Robwt .4rinstroiip. JID. PIID. Associate I'rofessor of I'etliatrics. Ukiiwrsity of British ('olumbia. Sunny Hill He;ilth ( 'eiit r i b for ('hiltlren. Vancouver. BC'. C'anatla: I

Fretlerick Palmei: AID, Professor of Pediatrics. University of Tennessee. Mempliis.TS, LJSA: Dinah Retlclihougli, MI>. FRAC'e I)evelopmeiital Pediatrician. Department of C'hiltl Development and Iiehabilitation, Royal ('hiltlrenk Hospital. ,\Iclbouime. Aiist ralia: D1, Rosenbloom, FRC'I: Petliatiic Seurologist. Studies ii i Child Development and Handicap. Department of ('hilt1 Health. Uiiiveixity of Liverpool, I,iverpool, UK: David Scruttoii, MSc (I"), Senior Lecturer. I'hysiothei~apy and Elioenginecring. ItistituteofC'hiId Health. I~~i i t lot i . UK: A1ic.e Shea, ScD (PT). Pliysicid Therapy Department, Association for liesearch and Etlucation. C'hiltlirn's Hospital, Boston, A I A . US.4: \\raylie Stuberg. PhD. P", Associate Professor antl I)irec.tor. PhysicalTherapy Jleyer Rehabilitation Institute. University ofSebixska Metlical ('elitel: Omt~lia, SB. USA.

Appendix B:

1,itrorlricfioti anrl User Iti .~trrictio~is The (;rosx Notor Fuiiction ('lassification System fi)i*('c~.ebral Palsy is based 011 self-initiated movement with ~ ) a r t i ( ~ l i l r emphasis 011 sitting (truncal control) and wallring. \\'lirn tlefiningon a5 level C'lassitiratioiiSSsteni, our primary eritcri- on was thiit the tlistinrtions i n motor function between levels must be clinically meaningful. Distinctions between levels of motor fuiiction tire based on functional limitations. the ncrtl for assistive technology including iiiobility devices (such as walkeis. c~utches, antl cknes) and \vheeletl mobility. and to a mucli lesserestent quality of movement. Level I inchdes chil- tlren with neuromotor impairnients wliose functional limita- tions ate less than what is typically associatctl with eei~briil palsy antl chiltlreii \viio have tratlitionally been diagnosetl as having"minimal brain cl~sfiinction"oi"cerebrral palsy of mini- mal severity".Tlie tlistinctions between Levels I antl 11. there- f o r ~ , are not as ~~ro~iouiiced as the tlistiiictioils between tlie other Levels. pai*ticularly for infants less tlian Zyears ofage.

The focus is on determining what level best relmseiits the child's present ahilities and limitations in motor function. Emphasis is on the chiltl's usual performance in home, school. ancl community settings. It is therefore importiuit to classify on ordinary performance (not best capacity). antl not to include judgements about prognosis. Remember the pi111)ose~ is to classicv a child's p~seent g r o ~ inotor fuiirtion. not to judge quality of movement or potential for improvement!

Tlietlesrriptionsoftlie6 levels are broad anrl are not intentl- etl to tlescribe the function of intlividuiil chiltlren. For example. an infant with hemiplegia\vho is unable to crawl on hands antl knees but otlieiivise tits the description of Level 1. ivoultl be cla+ietl in Level 1.Tliescale isordinal. with 110 iiiteiit that the distance between lerels be consideiwi equal or that childirn with eerebral palsy are equally tlistributetl among the 5 levels. A summary of the clistinctions bet\\wn each pair of levels is provitlecl to assist in determining tlie level that most closely resembles a child's cui-rent gross motor function.

The title for each level represents the highest level of mobil- ity that a child will achieve between 6-12 yeais ofage. \Ve rec- ognize that classification of motor function is dependent on ago, especially during infancy and early chiltlhood. For each' level, therefore, separate descriptions are provicletl for ehil- dreii in several age bands. The functional abilities and limita-

i

(: I{OSS l101'0 13 lprS('T1OX ( 'LASS I FI I 'AT1 0s S Y W E l l

tions for each age interval aiv intriitletl to serve ax guidelines, are not comprehensive. and are not norms. Children below age 2 should be coasidered at their correct age.

An effort has been made to eiiiphasize children's function rather than their limitations. Thus as ii general principle. the gross motor function of childi~n who are able to perform the funetions tlesc~ibctl in any ~)artirular level will probably be classified at or above that level: i n contrast. the gross motor function of childirn \vho caniiot perform the fuiictions of a ~iai~tic~ularlevel will likelybeclassitirtl Lelow that level.

Crossillotor Fri,icf ion Clasai&atioir Sydc~~n LEVEL I - \I'alks without restrictions: limitations in morc advanced gross motor skills. Before 2nd hiithclay: Infants inooc in and nut of sitting and floor sit ~vitli both haiitls free to maiiil~ul;itr ol)jrrts. Infants crawl on hantls antl knees. 1)uIl tc) stand antl take steps holding . onto fiirnituiv. Iiifaiits tvallc between 18 moiiths antl 2 yearsof age without the nwtl foraiiy assistive mobility tlevice. From age 2 to4th birthday: ('hiltlirn floor sit with both liantls f i w to manipulate objects. Alovenients in atid out of floor sit- ting a11tl stiintlillg ~ I P performed \vithout iidult a~.sistii~l(*e. ('Iiiltlreii \valk;ts the prcfertwl method of mo1)ility without the nerd for any assistive iiiobility tlcvire. From age 4to 6th birthday: ('liiltlri~n get into imrl out of. ancl sit in, a chair without the i icrtl for h i ~ ~ i t l s~ipport. ('Iiildreii move from the floor and from ~~liair~itti~igtostantli~ig\vitIiout tlic iieetl for ohjects for supl)ort. ('liiltlrrn walk intlooi~i and outtlooi.~, ant1 rlimb stairs. Emerging ability to run and jump. From age 6 to 12: ('liiltlreii \valk intloors and outtlooin. and climb stairs without limitations. ('hiltli~en ~~erfi)rm gross motor slrills includiiig runniiig aid juniping I,rlt speed, bal- a i i e ~ ~ . antl rooidination arc retlucetl. LEVEL I I - \Valks without assistivtb tlevicw: limitations walking outdoois antl in thc cominiiiiity . Before 2nd hiithtlay: Infants iiiaiiitiiin floor sitting but may

Infants creep on their stoinac~h or c~aivl 011 liantls and kiicws. Infants may pidl to stand and take steps holding onto furni- ture. From age2 to411 birthday: Cliiltlren f l o o r s i t u m y 11avedif- ticulty with balance when both hands IIP free to mani~)u1ate objects. Movrnieiits i n and out of sitting ilrt' performed with- out atlult assistaure. ('hiltlren 1)1111 to stand on a stable surfilce. ('l~iltlren crawl on haiids antl Irnees with a ~ ~ c i p r o ( d pattern. cruise holding onto furniture* ant1 \veIli usiiig an assistive mobility tlevice as preferi~d methotlsof mobility. From uge 4 to 6th birthtllty: ('hiltlren sit i n a chair with I)otli haiirls free to manipulateobjects. Chiltliwi move from the floor to standing and from chair sitting to staiiding but often require a stablr sui-f~c~e to pusli or pull up on with their arms. Children walk without the need for any assistive mobility devic~e'intloors antl for short distances 011 level surfaces out- tlooix. ('hiltlren climb stairs holding onto H railing air unable to run orjump. From age 6 to 12: Chiltlreti \wlk intloor~s aiitl outtloors. atitl climb stairs holding onto a railing csl)ci*ience limitations jvalking 011 uiieven surfaces and inclines, and \\dkiiig iii crowds or confined spaces. ('hildreii have at best only minimal ability to perforin gross motor skills such as runiiing aiitl jumping.

nwtl to use thrir haiitls for support to maintain 1). d I allcl'.

Uistirrctidiis between Lads I n i td 11: C'onipnred witli rlriltlren in Lerd 1,cliildreii iit Lerel Ilhnrie l int- it a t io it .y i ii t Ii e rnse o j pe rfo r 111 i i ig 111 o re )tic ii t t r a m it io it a; walk - iny oritdoors aiid in l?te coitiiiritnily: llre t i e d f o r aasislii-e mobili ty rlericea rrlwn begiiinitiy to riylk: qrrnlity of ,notwrrrnt: aitd tire ab i l i t y to ~ierfvrit i yross nrotor skilla .svicli 1t.s riiiitiiiiy a t id j t rn tp i i i~ .

LEVEL 111 - \Vnlks with assistive mo1)ility (Ievicus; l h i t a - tioiis \valking outdoors and i n the community. Before l i i t l birthtltiy: infants iiiaintnin floor sitting when the low 1)ac.k is supported. Infiriits roll i m i C . J W ~ foi~\vaid on their st oniachs. From age 2 to 4th birt1itl;ty: ('hiltlren maintaiii floor sitting often by 'W-sitting (sitting brt\vt~en flesetl ant1 internally rotated hips and knees) and may i q u i r e adult assistance tu assunie sitting. C'hiltlrcn c.rrep on their stoniitdi or crawl 011 liaiitls antl knew (often wit hotit 1wil)rnral leg movements) as theit primary metliotls of self-mobility ('hiltlien 11ia.y pu11 t o stand on a stable suifiice antl cruisr short distances. ('hiltli~eii may \vdk short clistanves inrloors using iiii assist ive mobility clevire antl adult assistance for steering ant1 t ai~ning. Ffoni age4 to6th birthday: ('liiltliwsit on a 'rrgulur chair but may require pelvic. or trunk support t o inasiinize hn;irl fuiic- tion. ('hiltlren move in and out of clitiir sitting rising a stublr surfare to ])iisIi on or pd1 111) with their arms, C'hiltlrrn walk with an assistive mobility devirc on level surf'accs antl climb stairs with assistance from an atlult. ('hiltlrcn frequently are transported when travelling forloag tlistanres or outdoors on uneven terrain. From age 6 to 12: C'hiltlren walk indoors orouttloors on a Irvel surfaracr with an assistive mobility c1evic.e. ('hiltlren niay rlinib stairs holding onto a railing. Depending on upper limb fuiic- tion. children propel a wlieelrhair ~iianually or are transported when tia\~elling for long distances or oettloors on uneven ter- rain.

l h t i i i c l i o i i s 6ctrr.erii Lerd.s I n i i d 111: Uiffretlre.s nre .see)i i n / l ie rlryrec! of nclrieretite,i/ of jrrnc!ioiiul i1106iIity. C'liildreii iti Lerel I l l irrerl rmisti i ie niobili ty clerices nrtd jreqt(ertt1y or tho .w to tr*nlk, tcJile ch ilrlreii iii L e d I1 do tiot require nssistit.e iiiobility (Iwices uftler age 4.

LEVEL 1V - Self-mobility with limitations; children are transpoi-tcd or usel)ower niobilit youtcloow antl in the commu- nity. I Before2ntl birthday: Infants have head control but trunk sup-

' port is iwliiiretl for floor sitting. Iiifants can roll to supine and niay roll to prone. From age 2 t o l t h birthday: C'hiltli*eii floor sit when plared, but are unable to maintain alignment and bidance without use of their hands for support. Children frequently require adaptive equipment for sitting antl standing. Self-mobility for short distances (within a room) is achieved through rolling, creeping on stomach, or cvwvling on hands and knees without reripro- ral leg movement. From age 4to 6th birthday: ('hiltlren sit on a chair but need atlaptiveseating for trunk control and to maximize halid func- tion. ChiltlreJi move in antl out ofrhair sitting with assistance from an adult or a stable surface to push or pull u p on with their arms. Chiltliwi niay at best walk short distances with a walker and adult supervision but have difficulty turning.antl

maintaining balanrc on uneven siirfures. ('hildren are trans- ported in the community. C'hildren may achieve self-mobility wing a p o w t ~ wheelchair. Fiwn age 6 to 12: Childrcii may muintain levels of function arhieved before age 6 or rely mole on wheeled mobility at home, school, antl iii the comniunity Cliiltlren niay achieve st4f-mobility using a po\ver\vheelchair.

1)istinctiony I h t i i ~ e t i Levels 111 and 11': Uvfereiices i n si t l ing abi l i ty and mobi l i ty exiat, ei)eii alloiiv'ny f o r e.rtensive w e of assist iiJe techioloqy. Cliildren i n Level I11 sit intlependently, have independent poor mobili ty, a n d walk with nssislirye iiio6iIity rlecicrs. C'lrildren i n Level I V ftrncfioii i n s i t - t i i iy (~rstrnlly strp1wrled) birt indepeilrlent mobi l i ty i s aery lini- ited.PIiildreii i i i Lerel Il 'are more likelyto6etrcitisportzrlor use p o w r mobili ty.

I,EVEL\~-Self-mol~ilityissevercly limitetleveiiwith theuse ofassistivr tec-hnology. Before h i t i biithday: Physical impairments limit voluntary control ofinovement. Infants are uqable to maintain antigrav- ity head and trunk postiires in prone antl sitting. Infants rrqiiiir atliilt assistanre to roll From age 2 to 12: Physical impairments restrict voluntary control of movement antl the abi1it.y t o maintain antigravisy head aiitl trunk postures.Al1 areasofmotorfuiictioii arelimit- ctl. Func.tionaI limitations in sitting ant1.standing are not fully compensated for through the use of adaptive equipment antl assistive technology A t Level I! children have no meiiiis of intle1)enclent mobility and are transported. Some cliiltlren achieve sclf-niobility using a power wheelchair with extensive athptations.

Uistinctiotis Iletir*ern Leilels I V and 1': , Cliildreii in Level Vlack independence eaen i n basic ant igrav i ty posttrral control. Self inability is acliieced only i f the child can lenrn Iioici to operate un electrically poirered wheelchaiz

Appentlis B copyright Seurodevelop~rntal C'linical Research Unit, 1995.

drrrptedfor piildirittiutr !Nr Jliry 19.W.

.-I rktr o ic'lrtlymrr ti tx

\\'e greatly appreciate the contributioiis of the following incli- vitluals us voting partiripants i n the iioniinal group process: Sandy Caik, Heather McCavin, AnnahIaria Tancretli, ('oleen Toal, AIarilyn Wright (Children's Developmental Kehabilitation Centre, C'hetloke Division, Chetloke-BIcMaster Hospitals, Hamilton, Ontario): Julie C'hiba-Branson, Elizabeth Kzrajbcr, KaKei Yeung (Hugh Macblillan Rehabilitation Centis, Toronto, Ontario): Jennifer Berg- C'arnegie. Kelly Cahill, Patti hIcGillivray. Shelley Potter (Siagara Peninsula Children's Centre, St Catharines, Ontario).

\Ve owespecial thanks to ourcolleagiies in the occupational therapy and physiotherapy departments at five Ontario chil- tlwn's treatment centres, who gave of their time to help us examiiie the reliability of the Gross Motor Function Classification System. These five centres are the Children's Developmental Rehabilitation Program, ChetlokeMrhIaster Hospitals, C'hedoke Division, Hamilton, Ontario: Chiltlren's

Kehabilitation Centre of Essex C'ounty, \Vintlsor, Ontario: Hugh 1\IacbIillan Rehabilitation C'entir, Toronto. Ontario; Siagara Peninsula Children's ('entre, S t C'atharines, Ontario: and Ottawa Cliildren'sTreatment Centre. Ottawa, Ontario. We also wish to acknowledge specifically the contributions of the respective coordinators i n each of these five eentres: Heather hlcOavin, Laurie Lessarct. Virginia Wright, Shelley Potter. and Diana JIcI ntosh.

The authors wish to express their thanks to Dawn \Vhitu~Il, our i.eseareh clerk throughout the period of the studies reported here.

Funding for these stritlics \\'as provided in part by griults from tho Easter Seals Remarch Institute antl Xational Health Research and Developinent Program. Dr Palisano's work was supported by a Career Scientist Amartl, Ontario Ministry of Hea1th.The work of Dr Rosenbauin antl Dr \Valter was sup- ported by a Sational Health SeientistAwai~tl, Health Canada. This research was contluctrtl within the Seurotlevelopme~ltal Clinical Research Unit, \vhich is funded by the Ontiwio hlinistry of Health through its Health Syste~n-I~iiiketl Research Unit program.

~ U f l 1 0 I ' U ' ~ L ] J ~ ~ ~ t l / / / l P l l / S *Robert Palisano, ScD, Associnte Professor, Uepurtnient of I'liysiciil Therapy, Allegheny University oftlir tIraltli Scictires. Pliiladrlphia. PA, us.-\; Peter Rouenbauin. i\I D. PKC'P Profcvisnr, Depurtnient of Pcdiiitrics: Steplien "alter, PIi D. Professor. Depurtlnrnt of('linical Epi&niinlngy and Biostutistics; Dianne Russell, MSc, Research Cooidinator, Seurorlevelopliient ti1 Clinical Research Unit; Ellen \\'ootl. AID, FRC'PAssistant Profewor, Drpartinent of Petliat rirs; Barbura Galuppi. BA. Seurotlevelopiiieiital Clinical 1iesc.arcli Unit, AlrAlaster Universits Hamilton. OX, C'anntla.

.

f l o r r e s l w t r r l o r r e /ojfir;uf r/i t /kor at Seurotlevelo~imetitnl c'liniciil Research Unit, i\lcl\lristcr University Furultg of Health Sciences, BuildingT- 16. Room 126.1280 Main Stipet West, Hamilton. OX. Crnatln I S 4K 1.

Gross Motor Function Clas..ifiratioli System in C'P liobrr/ I'ttlisrrtro P/ nl. 223