The Journal of Rheumatology

VOLUME 21: NO. 7

Editorials The ESR — Time Honored and Tradition Bound

A . W e i n s t e i n , J. D e l G i u d i c e 1177 What Can We Learn about Rheumatic Diseases by Studying Pirna Indians?

L T . H . J a c o b s s o n , S . R . P i i l e m e r 1179 Autoantibodies are Central to the Diagnosis and Clinical Manifestations of Lupus

J . B . H a r l e y 1183

Articles Specificity of Antibodies to Type II Collagen in Early RA A . D . C o o k , M . J . R o w l e y , A . S t o c k m a n ,

K . D . M u i r d e n , L R . M a c K a y 1186 Sulfate Metabolism is Abnormal in Patients with RA. Confirmation by I n V i v o Biochemical Findings H . B r a d l e y , A . G o u g h , R . S . S o k h i ,

A . H a s s e i l , R . W a r i n g , P . E m e r y 1192

Increased Capillary Permeability in Systemic Rheumatoid Vasculitis: Detection by Dynamic Fluorescence Nailfold Videomicroscopy

E. H a c h u l l a , M . P e r e z - C o u s i n , R - M . F l i p o , e t a l . . . 1197 Immunization of Patients with RA Against Influenza: A Study of Vaccine Safety and Immunogenicity A . C h a l m e r s , D . S c h e i t e l e ,

C. P a t t e r s o n , e t a l 1203 Outcome in Patients with RA Receiving Prednisone Compared to Matched Controls

R . M c D o u g a l l , J. S i b l e y , M . H a g a , A . R u s s e l l . . . . 1207 Expression of Muscarinic Cholinergic Receptors on Lymphocytes in Various Subsets of RA and Their Variabilities Connected with Treatment

H . L a s k o w s k a - B o z e k , A . F i l i p o w i c z - S o s n o w s k a , A . Z u b r z y c k a - S i e n k i e w i c z , J. R y z e w s k i 1214

A Canadian Survey of Current MTX Prescribing Practices in RA

D . C o l l i n s , N . B e l l a m y , J. C a m p b e l l 1220 Underrecognized Postdosing Reactions to MTX in Patients with RA J . T . H a l l a , J . G . H a r d i n 1224 The Clinical and Research Significance of the ESR

F. W o l f e , K. M i c h a u d 1227 RA in Tlingit Indians: Clinical Characterization and HLA Associations D . W . T e m p l i n ,

G . S . B o y e r , A . P . L a n i e r , e t a l 1238

J U L Y 1994

Evaluation of a German Version of the Physical D imensions of the HAQ in Patients with RA

P . Brühlmann, G . S t u c k i , B . A . M i c h e l 1245 Q uality of Life in RA: Validation of a Spanish V ersion of the AIMS (Spanish-AIMS)

M . A b e l l o - B a n f i , M . H . C a r d i e l , R . R u i z - M e r c a d o , D . Alarcön-Segovia 1250

Osteocalcin in Patients with RA. A One-Year Followup Study H . F r a n c k , T . H . I t t e l ,

O . T a s c h , G . H e r b o r n , R . R a u 1256 Clinical Utility and Serological Connections of Anti-RA33 Antibodies in S L E

D . A . I s e n b e r g , G. S t e i n e r , J . S . S m o l e n 1260 L ipid Profiles in Patients with S L E

K . H . L e o n g , E . T . K o h , P . H . F e n g , M . L B o e y 1264 Localization of Endothelin-1 and its Binding S ites in Scleroderma Skin R . V a n c h e e s w a r a n ,

A . A z a m , C . B l a c k , M . R . D a s h w o o d 1268 Sensitivities of Noninvasive Tests for CNS Vasculitis: A Comparison of Lumbar Puncture, C T , and MRI J . H . S t o n e , M . G . P o m p e r ,

R . R o u b e n o f f , T . J . M i l l e r , D . B . H e l l m a n 1277

A nalysis of Steroid Related Complications and Mortality in TA: A 15-Year Survey of 4 3 Patients G . N e s h e r , M . S o n n e n b l i c k ,

Y. F r i e d l a n d e r 1283 Aspergil lus Spondylodiscitis: Successful C onservative Treatment in 9 Cases

B . C o r t e t , R . R i c h a r d , X . D e p r e z , e t a l 1287 Hyperprolactinemia in Reiters Syndrome

L . J . J a r a , L H . S i l v e i r a , M . A . C u e l l a r , C. J. P i n e d a , E. S c o p e l i t i s , L R . E s p i n o z a 1292

P atient Utilities in A S and the Association w ith Other Outcome Measures

C. B a k k e r , M . R u t t e n - v a n Mölken, A . H i d d i n g , E. v a n D o o r s l a e r , K. B e n n e t t , S . v a n d e r L i n d e n 1298

T reatment of PsA at the Dead Sea S. S u k e n i k , H . G i r y e s , S . H a l e v y , L . N e u m a n n , D . F l u s s e r , D . B u s k i l a 1305

Factors Affecting Articular Cartilage Thickness in OA and Aging R . L . K a r v o n e n , W . G . N e g e n d a n k ,

R . A . T e i t g e , A . H . R e e d , P . R . M i l l e r , F. F e r n a n d e z - M a d r i d 1310

C o n t e n t s c o n t i n u e d o p p o s i t e i n s i d e b a c k c o v e r . . .

PRINTED IN CANADA — ISSNI 0315-162X

C O N T E N T S ( c o n t i n u e d f r o m f r o n t c o v e r )

Abnormal Thermoregulatory Responses in Patients with RSDS

A . H e r r i c k , K. E i - H a d i d y , D . M a r s h , M . J a y s o n 1319

Comparison of A C T H and Triamcinolone Acetonide in the Treatment of Acute Gouty Arthritis

L B . S i e g e l , J . A . A I I o w a y , D J . N a s h e l 1325

Capillary Permeability in FM W. G r a s s i , P . C o r e , G . C a r l i n o , F. S a l a f f i , C. C e r v i n i 1328

Somatomedin C (IGF-1) Levels Decrease Düring Acute Changes of Stress Related Hormones. Relevance for FM

G . F e r r a c c i o l i , P . G u e r r a , V. R i z z i , e t a l 1332

FM in FMF P . L a n g e v i t z , D . B u s k i l a , R . F i n k e l s t e i n , e t a l . . . . 1335

Contribution of Neuromuscular Impairment to Physical Functional Status in Patients with Lumbar Spinal Stenosis

G . S t u c k i , M . H . L i a n g , S J . L i p s o n , A . H . F o s s e l , J . N . K a t z 1338

Pediatric Rheumatology aCL in Pediatric Patients with HIV

L C a r r e h o , I. M o n t e a g u d o , F . J . Löpez-Longo, e t a l 1344

Workshop Report: Research in Pediatric Rheumatology

D . N . G I a s s , B . S . N e p o m , P . H . W h i t e , L E . S h u l m a n 1347

Case Reports Intravenous Cyclophosphamide Pulses in the Treatment of Pyoderma Gangrenosum Associated with RA

A . Z o n a n a - N a c a c h , F . J . J i m e n e z - B a l d e r a s , P . M a r t i n e z - O s u n a , G . M i n t z 1352

A n Association of PMR with Myelodysplastic Syndromes

M . K o h l i , R . M . B e n n e t t 1357

An Association Between Refractory HELLP Syndrome and aPL Düring Pregnancy

M . H . O r n s t e i n , J . H . R a n d 1360

Gout Düring Pregnancy J . T . K e l s a l l , D . P . O ' H a n l o n 1365

Correspondence Factors Predicting Outcome in RA

J . G . J o n e s 1367 Reply D . v a n Z e b e n , F . C . B r e e d v e l d 1367 aPL in Rheumatic Fever Chorea R . E . A . S . D i n i z ,

J. G o l d e n b e r g , L E . C . A n d r a d e , e t a l 1367 Reply F. F i g u e r o a , X . B e r r i o s , M . G u t i e r r e z , e t a l 1368 Primary APS or S L E related APS: From Theory to Practice J - C . P i e t t e 1368 Reply R . A . A s h e r s o n 1369 aCL in Klinefelter's Syndrome

G . B a j o c c h i , G . S a n d r i , F. T r o t t a 1370 Reply J. M . D u r a n d , G . K a p l a n s k i , J. S o u b e y r a n d . . 1370 Cofactor (ß 2 -Glycoprotein 1) Dependent aCL and Thrombosis J. K a b u r a k i , M . K u w a n a ,

Y . l k e d a , M . Y a m a m o t o , S . K a w a i , E . M a t s u u r a ... 1371 Reply J. O r d i R o s , A . S e l v a - O ' C a l l a g h a n ,

P . P e r e z - P e m a n , C . F a l g a , E . C u c u r u l l 1371 Recurrent Reflex Sympathetic Dystrophy as a Manifestation of S L E D . H . N e u s t a d t 1372 Reply B . E . O s t r o v 1372 Fat Necrosis from im G T G J . M . S o w a 1372 Reply J. M c C a i n , T W i z d a W e s t 1373

Letters TCR Vß Selection from DRB1*401*0101 Patient with RA Complicated by CD8 + T Cell Infiltrated Rheumatoid Pericarditis A . T r a v a g l i o - E n c i n o z a ,

J - M . A n a y a , A . D u p u y d ' A n g e a c , J . S a n y , T . R e m e ..1373 Factors Influencing the Prevalence of APS in S L E U . P i c i l l o , S . M i g l i a r e s i , M . R . M a r c i a l i s ,

F. L a P a l o m b a r a , G . T i r r i 1375 Immunomodulatory Therapy of Recurrent Purpura Associated with SS . Effect of Oral Gold Compound /. K a t a y a m a 1376 Chronic Hepatitis C and SS J - L . P o e t ,

I. T o n o l l i - S e r a b i a n , P . P . G a r n i e r 1376 Membranous Nephropathy Developing Düring the Course of DM H . M a k i n o , K. H i r a t a ,

M . M a t s u d a , T. A m a n o , Z . O t a 1377 Orchitis: An Unusual Feature in Relapsing Polychondritis J - F . M a i l l e f e r t , B . D e W a z i e r e s ,

F. M e i g n a n 1378

Book Reviews Antibodies to Endothelial Cells and Vascular Damage 1379 Occupational Musculoskeletal Disorders 1379 Oxford Textbook of Rheumatology 1380 Notices 1381

x v i i i

Evaluation of a German Version of the Physical Dimensions of the Health Assessment Questionnaire in Patients with Rheumatoid Arthritis PIUS B R Ü H L M A N N , G E R O L D STUCKI, and BEAT A . M I C H E L

ABSTRACT. O b j e c t i v e . Our objective was to translate and adapt the disability section of the health assessment questionnaire (HAQ) into German (HAQ-G) to suit Swiss-German conditions and to test its metric properties, reliability, and validity. M e t h o d s . We tested 62 consecutive patients with rheumatoid arthritis (RA) attending the outpatient Clinic of the Department of Rheumatology, University Hospital Zürich. A l l patients fulfilled the American Rheumatism Association 1987 revised criteria for R A . The translation was done by 2 translators aware of the objective of the questionnaire and some questionable items were discussed and resolved in a panel by 4 rheumatologists including one bilingual clinical researcher. Test-retest reliability was assessed with Pearson's correlation coefficient on the scores of 2 questionnaire mailed in a 10-day interval. The internal consistency was assessed with Cronbach's coefficient alpha. To assess the construct validity, we compared the H A Q scores to clinical, laboratory, and radiological variables of disease activity and outcome. To assess criterion validity, we compared physicians' assessment of functional class (observed disability) to the H A Q (referred disability). The content validity was assessed in a multivariate model explaining H A Q scores with a variety of other meas-urements of disease activity and outcome. Results. The test-retest reliability was 0.94; the internal consistency was 0.92; the criterion validity was 0.76; and correlations with other disease variables ranged from 0.39 (Larsen radiological score) to 0.66 (grip strength). C o n c l u s i o n . The H A Q - G is a reliable and valid instrument for measuring functional disability in a German speaking population with R A . (J R h e u m a t o l 1994;21:1245-9)

Key I n d e x i n g Terms: P H Y S I C A L F U N C T I O N A L DISABILITY R H E U M A T O I D ARTHRITIS

G E R M A N V E R S I O N H E A L T H A S S E S S E M E N T QUESTIONNAIRE

Assessment of rheumatoid arthritis (RA) includes measure-ments of process, prognosis, and outcome1. Outcome is the suffering and loss of health experienced by an individual as a result of the process of disease2. Death, physical disabil­ity, discomfort, treatment side effects, and economic impact have been identified as primary outcome dimensions. Although the importance of physical disability has been recognized since the earliest days of the speciality of rheumatology3, reliable and valid measures were not deve-loped until 19804. One of the most widely used instruments to measure functional disability is the Health Assessment Questionnaire ( H A Q ) 2 5 . It measures function in dressing, arising, Walking, hygiene, reaching, gripping, and in other

F r o m t h e D e p a r t m e n t of R h e u m a t o l o g y a n d P h y s i c a l M e d i c i n e , U n i v e r s i t y H o s p i t a l , Zürich, S w i t z e r l a n d a n d t h e R o b e r t B . B r i g h a m M u l t i p u r p o s e A r t h r i t i s a n d M u s c u l o s k e l e t a l Disease C e n t e r s , B r i g h a m a n d Women's H o s p i t a l , H a r v a r d M e d i c a l School, B o s t o n , M A , U S A . P . Brühlmann, M D , A s s i s t a n t P r o f e s s o r of R h e u m a t o l o g y , U n i v e r s i t y H o s p i t a l Zürich; G. S t u c k i , M D , Research F e l l o w i n R h e u m a t o l o g y , B r i g h a m a n d Women 's H o s p i t a l ; B . A . M i c h e l , M D , P r o f e s s o r of R h e u m a t o l o g y , U n i v e r s i t y H o s p i t a l Zürich. Address r e p r i n t requests t o D r . M e d . P . Brühlmann, R h e u m a k l i n i k u n d p h y s i k a l i s c h e s I n s t i t u t , Universitätsspital, G l o r i a s t r a s s e 2 5 , 8 0 9 1 Zürich, S w i t z e r l a n d . S u b m i t t e d A u g u s t 3 0 , 1993 r e v i s i o n a c c e p t e d December 3, 1 9 9 3 .

activities. The questionnaire is self-administered and may take less than 5 min to complete5. Its reliability and validi­ty has been demonstrated in different languages and contexts5. In a number of studies, the H A Q has been shown to detect changes in clinical Status and it has been used as a primary endpoint in rheumatic disease trials6. The H A Q has predictive validity for work disability, resource utilization7, peptic ulceration8, and death5.

We translated and adapted the disability section of the H A Q into German (HAQ-G) to suit Swiss-German conditions and tested its metric properties, reliability, and validity.

MATERIALS AND METHODS Patients. We enrolled 62 consecutive patients with R A attending the rheu­matology outpatient clinic, University Hospital, Zürich. A l l patients fulfilled the American Rheumatism Association (ACR) 1987 revised criteria 9 for the Classification of R A .

T r a n s l a t i o n a n d c u l t u r a l a d a p t a t i o n of t h e H A Q . The primary translation was done by 2 translators aware of the objective of the questionnaire. The emphasis was to attempt the best idiomatic rather than pure vocabulary equivalence 1 0. A few questionable items were discussed and resolved by 4 rheumatologists including one bilingual clinical researcher with experience in the use of the instrument in clinical studies, 2 with a general internal medicine background, and one with additional training in physical medi­cine. The following modifications in the Swiss-German adaptation (Table

Brühlmann, et a l : G e r m a n v e r s i o n H A Q 1 2 4 5

Table 1. G e r m a n version of the H A Q physical disability dimension [ a l l dimensions Start with the question: a r e you able to ("Können S i e " ) ]

Ankleiden und Körperpflege

- sich selber ankleiden, Kleider zuknöpfen und Schuhe binden?

- Ihre Haare waschen?

Aufstehen

- von einem Stuhl ohne Armlehne aufstehen?

- ins Bett gehen und aufstehen?

Eissen

- das Fleisch mit dem Messer schneiden?

- ein gefülltes Glas zum Munde führen?

- einen Milchkarton (Tetrapack) öffnen?

Gehen

- auf ebener Strasse gehen?

- Treppen steigen?

Körperpf l ege

- sich ganz waschen und abtrocknen?

- ein Vollbad nehmen?

- auf die Toilette gehen?

Heben

- einen 2 kg schweren Gegenstand (z.B. einen Sack Kartoffeln) über Kopfhöhe heben bzw.

herunternehmen?

- sich bücken, um ein Kleidungsstück vom Fussboden aufzuheben?

Greifen und Öffnen

- eine Autotüre öffnen?

- ein Konfitürenglas öffnen, welches schon einmal offen war?

- einen Wasserhahn auf- und zudrehen?

Andere Tätigkeiten

- einkaufen gehen?

- in ein Auto ein- und aussteigen?

- Haushaltarbeiten (z.B. Staubsaugen) oder Gartenarbeiten verrichten?

1) were made: (a) "Cl imb up five steps" was changed to "Can you climb stairs"; (b) "Reach and get down a 5-pound object (such as a bag of sugar) from just above your head" was changed to "Can you lift and reach a 2 kilo object above your head"; (c) the heading "gr ip" was changed to "grip and open"; (d) aids and devices: "walker" and "built up or special Uten­sils" were dropped since walkers are rarely used as the only device (patients who need a walker have usually also a wheelchair for greater distances; built up or special Utensils were specified under "other").

with some difficulty (1), with much difficulty (2), unable to do (3). The highest component score in each category determines the score for the category unless aids or assistance are required. Dependence on equipment or physical assistance increases a category score of < 3 by plus I. Category scores are averaged to give the disability index, a value from 0 to 3.

S c o r i n g . Scoring of questionnaires was done in accordance with the origi­nal H A Q using the following categories (points): without any difficulty (0),

Study d e s i g n . The questionnaire was given to the patients at a regularly sched-uled outpatient clinic visit. The same day the patient was evaluated clini-cally, laboratory tests were performed, and radiographs taken. The metric properties of the instrument and the validity were studied on this data. To assess the test-retest reliability the questionnaire was mailed twice with an

1 2 4 6 The J o u r n a l of R h e u m a t o l o g y 1 9 9 4 ; 2 1 : 7

interval of 10 days, 3 months after the cross sectional evaluation. Patients were therefore already familiär with the questionnaire from Time Point 1 with the advantage of excluding a learning effect.

R e l i a b i l i t y . The test-retest reliability was assessed with Pearson's correla-tion coefficient. To assess the internal reliability, an analysis of internal consistency using Cronbacrf s coefficient alpha was performed on the overall scale as well as on the 3 components addressing Upper extremity function (eating, reach, grip) and the 3 components addressing lower extremity func­tion (arising, Walking, activity). The relationships between the 8 compo­nents were evaluated in a correlation matrix using Spearman's correlation coefficient. In a factor analysis, the loading of the 8 components and total interperson variability explained by the factors was studied. V a l i d i t y . To assess criterion validity, we correlated the H A Q (referred dis­ability) to functional disability as recorded by the physician (observed dis­ability) and to the A C R functional class 1991 as recently published by Hochberg, et a l u .

To test the construct validity, we hypothesized a strong relationship between functional disability and variables of disease activity (swollen and tender Joint count; morning stiffhess; physicians global disease activity rated on a numerical rating scale; erythrocyte Sedimentation rate (ESR), C-reactive protein (CRP), anatomical damage (Larsen radiological score) 1 2, pain (11 point numerical rating scale, ränge 0-10), and global health. We hypothe­sized that grip strength (measured with a vigorimeter) would correlate most strongly with the grip domain and less with the other domains of the upper extremity and less with lower extremity domains. For Walking time we hypothesized that the walk domain would correlate most strongly. We also hypothesized that the physical disability score discriminates between patients with a short versus a long disease duration. For all correlations we used Spearman's correlation coefficients because the variables were either non-parametric or not normally distributed.

If the H A Q has a high content validity in reflecting the impact of the dis­ease, different attributes of the disease process should explain important amounts of its variability. Thus we studied the relationship of physical dis­ability to different aspects of the disease process in a biological multivari-ate model. The variables for the final model were selected in a stepwise regression analysis of groups of variables (level to stay: p = 0.2). The fol-lowing groups and variables were considered: demographic measures (age, sex), laboratory variables (ESR, CRP, thrombocytes, erythrocytes, lym-phocytes, Singer-Plotz titer, Waaler-Rose titer, hemoglobin, iron, ferritin), articular indices (tender Joint count, Ritchie count, swollen Joint count), Performance measurement (grip), Symptoms (pain, morning stiffness), ana­tomical damage (Larsen score), and disease duration. The variables select­ed in the group analysis were evaluated in a stepwise selection process with a level to enter of 0.1 and to stay of 0.05.

R E S U L T S Sixty-two patients completed the questionnaire at Time Point 1 and 50 patients completed the questionnaire at Time Points 2 and 3. All items were filled in, no items gave rise to mis-understanding. The baseline characteristics of the patients are shown in Table 2.

The test-retest reliability for the instrument was 0.94. The reliability for the categories ranged from 0.74 (grip) to 0.94 (hygiene). The internal consistency reached an alpha of 0.92, the correlation of the individual items with the total ranged from 0.53 (walking) to 0.82 (reach). A similar high internal consistency (alpha = 0.92) was found for the 5 domains representing upper extremity functioning. The correlation of the domains with the average upper extremity score ranged from 0.74 (grip) to 0.82 (dressing). The 3 lower extremity domains showed a Cronbach's alpha of 0.72 and the corre-

Table 2. Baseline demographic and c l i n i c a l characteristics and HA Q - G scores of the 62 patients with R A

Number of H A Q - G Score Patients

(N = 62) (SD)

Sex Male 23 1.1 (0.8) Female 39 1.1 (0.8)

Age group < 49 (5.7) 15 1.1 (0.8) 49 to 62 (7.2) 18 1.4 (0.7) 62 to 71 (9.7) 14 0.8 (0.8) > 71 (10.3) 15 1.0 (0.8)

Functional class A C R 1991 I 9 0.1 (0.1) II 19 0.7 (0.7) III 32 1.5 (0.4) IV 2 2.6 (0.3)

Rheumatoid factor (Singer Plötz) (n = 61) Negative 31 0.9 (0.8) Positive 30 1.3 (0.8)

lation of the items with the average lower extremity score ranged from 0.52 (rise) to 0.56 (activity). The correlation matrix between the domains yielded correlation coefficients of 0.37 (walking and eating) to 0.78 (hygiene and reach) (Table 3). The principal component analysis resulted in one factor explaining 64% of the total variance of the scale.

The correlation of the H A Q with the Steinbrocker scale was 0.6 (p < 0.01) and with the A C R 1991 functional scale 0.76 (p < 0.01) (Table 2). The correlations between func­tional disability and disease activity measurements, anatom­ical damage, discomfort, and global health were all signifi-cant (p < 0.05) and ranged from 0.39 (Larsen score) to 0.66 (grip strength) (Table 4). Age and sex were not univariate correlates of the H A Q .

The correlation of grip strength with the domains representing upper extremity function ranged from —0.50 (gripping) to -0.63 (reaching) and the correlation with lower extremity domains from -0.29 (walking) to -0.48 (activity). The correlation of walking time with the lower extremity domains ranged from 0.35 (rise) to 0.47 (Walk­ing) and with the upper extremity domains from 0.22 (eat­ing) to 0.49 (hygiene).

Patients with a disease duration of < 1.5 years had a much lower average disability score of 0.7 than patients with a dis­ease duration of > 11 years showing an almost doubled H A Q score of 1.3 on average.

For the multivariate model, the following variables had univariately a p value of less than 0.2 in the group selection and were considered for selection: CRP, ESR, ferritin, iron, erythrocyte count, grip and Ritchie Joint count, Larsen score, pain, and morning stiffness. In the stepwise forward selec­tion process, grip (explaining 38% of the total Variation of the H A Q score), morning stiffness (explaining an addition-al 17%), ferritin (7%), CRP (4%), and Ritchie Joint count

Brühl m a n n , et a l : G e r m a n Version H A Q 1 2 4 7

Table 3. Spearman correlation coefficients among the components o f the H A Q - G

Eating Reaching Grip Dressing Hygiene Arising * Walking Activity

Eating 1 Reaching 0.71 1 Grip 0.73 0.65 1 Dressing 0.74 0.75 0.62 1 Hygiene 0.66 0.78 0.63 0.77 1 Arising 0.63 0.58 0.57 0.62 0.70 1 Walking 0.37 0.47 0.40 0.45 0.53 0.50 1 Activity 0.64 0.69 0.66 0.59 0.64 0.50 0.50

Table 4. Relationship of the H A Q - G score with biological disease variables

Variable Median (Quartiles)

Correlation with H A Q - G Score t

Swollen Joint count 5 (2; 11) 0.31** Tender Joint count 6 (2; 15) 0.57** Morning stiffness (min) 15 (0; 60) 0.5** ESR (mm/h) 18 (12; 30) 0.26* C R P (mg/dl) 1.8 (0; 4, 6) 0.46** Activity physician (NRS* 0-10) 3 (2; 5) 0.57** Larsen score (ränge 0-40) 10 (8; 17, 5) 0.39** Grip strength (kp/cm 2) 0.6 (0.38; 0.9) -0 .66** Walktime (s/50 m) 32 (27; 35) 0.49** Global health (Likert 0-3) 2 (1; 2) 0.56** Pain (NRS 0-10) 5 (3; 6) 0.53** Disease duration (years) 5.2 (1.44; 11.6) 0.29*

** p value < 0.01, * p value < 0.05. r Spearman's correlation coefficient. * NRS numerical rating scale.

(2%) were selected. The total model r2 was 68% (p < 0.01).

DISCUSSION The adaptation of the H A Q for a Swiss-German context required no major cultural adaptation since the cultural similarity is high. Because German and English are linguis-tic relatives, most items could be translated with vocabulary equivalence. Few questions required a different phrasing to avoid misunderstanding and to guarantee idiomatic equivalence.

The metric properties of the H A Q - G were similar to those presented in the original report2 and in other adaptations5. The internal consistency was high and indicates that the com­ponents of the scale measure the same construct. The items correlated all with each other, but there was no redundan-cy; this indicates that each domain addresses a somewhat different aspect of functional disability. The test-retest relia­bility was similar to reported evaluations which reported correlations between 0.87 and 0.965. The high correlation with other measurements of functional disability such as the Steinbrocker functional scale and even more with the recently developed A C R functional class 1991 demonstrates that both instruments measure a similar construct. As expected, we

found strong correlations with variables of disease activity as well as Joint destruction. This is consistent with the con-cept that functional disability is influenced by process as well as destruction and may explain why grip strength, another combined measurement of both dimensions, was the strongest correlate.

The finding that 68% of the Variation of the H A Q - G can be explained by a few biological variables reflects the strong relationship between disease process and functional disabil­ity. Since heterogeneous dimensions of the disease includ­ing laboratory variables and signs and Symptoms explained relevant proportions of the variability of the H A Q - G , it can be concluded that this concept of functional disability com-prehensively addresses the impact of RA. The responsive-ness of the scale has not yet been studied in this Validation. However, the sensitivity of the H A Q has been demonstrated in multiple studies using the original version as well as other cross cultural adaptations. Since we were able to demonstrate the similarity of the instrument with respect to metric proper­ties, reliability, and validity, we expect a similar responsive-ness for this German version of the H A Q .

We conclude that the German version of the H A Q retains the characteristics of the American original and is a reliable and valid instrument to measure functional disability in German speaking patients with RA.

ACKNOWLEDGMENT The authors thank Matthew H . Liang, M D , M P H , for helpful discussions and Susanne Stucki, M E d for help in preparation of the manuscript.

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Brühlmann, et a l : G e r m a n v e r s i o n H A Q 1 2 4 9