Uric Acid, Microalbuminuria and Cardiovascular Events in High-Risk Patients

Abstract

Background: Elevated levels of serum uric acid and albuminuria are associated with cardiovascular disease, but the relationships have not consistently been demonstrated to be independent of hypertension, other risk factors, or each other. The purpose of this study was to evaluate people at high risk for cardiovascular disease for the influence of uric acid and microalbuminuria on cardiovascular events. Methods: Consecutive consenting patients undergoing elective angiography (n = 316) had coronary artery disease, risk factors, renal function and diuretic use assessed at baseline. Cardiovascular mortality and major clinical events (myocardial infarction, stroke, amputation, and kidney failure) were ascertained over 5 years. Results: Cardiovascular events occurred in 10% of the patients. Significant correlates (p < 0.05) of cardiovascular events with baseline measures included uric acid ≧5.2 mg/dl, total cholesterol ≧200 mg/dl, severe angiographic coronary artery disease, loop diuretic therapy, and diagnosis of hypertension. A stepwise Cox modeling procedure identified uric acid (p = 0.040), the interaction of hypertension and uric acid (p = 0.029), the interaction of total cholesterol and severe coronary artery disease (p = 0.001) and loop diuretic therapy (p = 0.009) as significant independent predictors of events. Although microalbuminuria was not retained in the final multivariate model, it was associated with poorer cardiovascular disease outcomes. The mean event-free survival for albumin-to-creatinine >30 mg/g was 51 months and for albumin-to-creatinine <30 mg/g the mean was 57 months (p = 0.021). Conclusions: Uric acid ≧5.2 mg/dl independently imparted a 3.5-fold increased risk (OR 3.5, 95% CI 1.0–11.9) for cardiovascular death and major clinical events over a 5-year period. Uric acid may be a contributing factor to the progression of atherosclerosis and its complications.