RESPONSIVENESS OF KEITEL FUNCTIONAL INDEX COMPARED WITH LABORATORY MEASURES OF DISEASE-ACTIVITY IN RHEUMATOID-ARTHRITIS

This study compares functional changes to change in measures of disease activity following the introduction of slow-acting anti-rheumatic drugs (SAARD) in patients with active rheumatoid arthritis (RA). Clinical and laboratory variables were simultaneously monitored at 6-monthly intervals, over approximately 18 months. Function was measured by a performance testing, the Keitel function index (KFI), which was divided into sections representing small and large joints [hand (HFI); wrist (WFI) and limb function index (LFI)]. One-hundred-and-fifteen patients were studied, of whom 21 were male. The mean age of the subjects was 49 yr (S.D. +/- 12) and mean duration of disease 7 yr (S.D. +/- 7). The mean KFI at entry was 38 (S.D. +/- 18) while at the end of the study it was 31 (S.D. +/- 17) (P < 0.0001). The change in KFI following therapy correlated with the change in Ritchie articular index (RAI) (r = 0.4; P < 0.0001), early morning stiffness (EMS) (r = 0.3; P = 0.004), swollen joint count (JC) (r = 0.4; P = 0.0005), C-reactive protein (CRP) (r = 0.2; P < 0.05) and Lansbury systemic index (LSI) (r = 0.35; P = 0.002), but not with change in Westergren erythrocyte sedimentation rate (ESR) or change in time to onset of fatigue. Multiple regression analysis showed that 32% of the variation in KFI at the end of the study could be predicted by a combination of ESR, sulphasalazine therapy, RAI, disease duration and chloroquine treatment at onset (P < 0.05). When HFI at end of study was the dependent variable, 21% of the variation could be predicted by a combination of ESR, CRP, Lansbury systemic index and JC at onset (P < 0.05). The duration of disease did not significantly influence the potential for change in functional status. This study showed that detailed measurement of function is important in assessing RA activity. Functional impairment in RA is a dynamic process influenced by changes in clinical disease activity with treatment.