The association between serum uric acid concentrations and inflammation in patients with rheumatoid arthritis (RA) has been still controversial.
A total of 172 patients with RA who added leflunomide to methotrexate (MTX) in their treatment regimens were enrolled in this study. Twenty-seven RA patients taking MTX without leflunomide were also recruited in order to assess the fractional excretion of uric acid (FEUA).
After leflunomide therapy for an average of 4.6months, serum uric acid concentrations had significantly decreased compared to baseline concentrations (p<0.001). Patients treated with a combination of MTX and leflunomide (n=23) showed higher FEUA than those treated with only MTX (n=27) (p=0.007). Differences in serum uric acid concentrations after leflunomide therapy were significantly associated with those in serum creatinine concentrations (B coefficient=3.081, p<0.001), but not with those in acute phase reactants including ESR and CRP.
This study determined that leflunomide reduced serum uric acid concentrations through increased urinary excretion of uric acid, which might not reflect changes in disease activity status in RA. This implies that uric acid may not influence systemic inflammation in RA.