Serum Uric Acid is Independently Associated with Hypertension in Patients with Rheumatoid Arthritis

Hypertension (HT) is highly prevalent in rheumatoid arthritis (RA). Serum uric acid (SUA) has been associated with HT in the general population. The mutual exclusion of gout and RA, and the systemic inflammatory component of RA may alter this association in this patient population. We explored a potential association between SUA levels and HT in RA and evaluated whether this association is independent of HT risk factors, RA characteristics and relevant drugs. A total of 400 consecutive RA patients were assessed. SUA and complete biochemical profile were measured. Demographic, HT-related factors, RA characteristics and drugs were assessed as potential covariates. Results were analysed using binary logistic models to test the independence of the association between SUA and HT. SUA levels were higher in hypertensive compared to normotensive RA patients (5.44+/-1.6 mg dl(-1) (323.57+/-95.17 micromol l(-1)) vs 4.56+/-1.1 mg dl(-1) (271.23+/-65.43 micromol l(-1)), P<0.001). When adjusted for HT risk factors, renal function, RA characteristics, non-steroidal anti-inflammatory drugs, oral prednisolone, cyclosporine, leflunomide and low-dose aspirin, the odds of being a hypertensive RA patient per 1 mg dl(-1)(59.48 micromol l(-1)) SUA increase were significantly increased: OR=1.59 (95% CI: 1.21-2.1, P=0.001). This was also significant for the subgroup of patients who were not on diuretics (OR=1.5, 95% CI: 1.1-2.05; P=0.011). This cross-sectional study suggests that SUA levels are independently associated with HT in RA patients. Prospective longitudinal studies are needed to confirm and further explore the causes and implications of this association.