C-reactive protein in the serial assessment of disease activity in rheumatoid arthritis.

C-reactive protein (CRP) levels were measured in 105 patients with rheumatoid arthritis (RA) during treatment with slow-acting anti-rheumatoid drugs D-penicillamine, alclofenac, hydroxychloroquine, gold, sulphasalazine and azathioprine. A control group treated with aspirin alone was also included. Patients were assessed clinically (pain score, articular index and summated change score) and in terms of acute-phase reactants (CRP, haptoglobin, fibrinogen, ESR and plasma viscosity) at eight separate clinic visits during the 6-month treatment period. The estimation of CRP was found to be more useful than haptoglobin, fibrinogen or ESR as an index of disease activity.