Correlates of functional disability in early rheumatoid arthritis: a cross-sectional study of 706 patients in four European countries.

In this cross-sectional study of 706 European patients with rheumatoid arthritis (RA) of < or = 4 yr duration, we examined possible correlates of functional disability assessed by the Health Assessment Questionnaire. First, we examined a subsample of 237 Norwegian patients. The Ritchie index, sex, age, erythrocyte sedimentation rate (ESR) and disease duration correlated significantly with disability, whereas serum rheumatoid factor, hand X-ray changes and educational level did not. Subsequently, we cross-validated these findings in a similar sample of 469 French, Dutch and Northern Irish patients. The results supported the Ritchie index, sex, ESR and disease duration as significant correlates of disability, whereas rheumatoid factor, age and education were not significantly correlated with disability. The correlation between X-ray changes and disability could not be cross-validated. The main findings of this study are that female sex correlates significantly with disability even early in the course of RA, whereas the rheumatoid factor does not.