Serum uric acid as a marker of all-cause mortality in an elderly patients cohort

Introduction: There is growing evidence of the role of serum uric acid (SUA) as a risk factor for cardiovascular and renal disease. We analyze the association between baseline SUA and overall mortality in a cohort of elderly patients followed prospectively for 5 years. Patients and Methods: 80 clinically stable patients, median age 83 years (range 69-97), 31.3% men, 35% diabetic 83% hypertensives, randomly recruited in Geriatrics and Nephrology consultations between January and April 2006, were followed for 5 years. We measured baseline SUA and serum creatinine and we estimated glomerular filtration rate (GFR) with MDRD abreviated. In patient of Nephrology Department we measured proteinuria in collection urine 24 hours and patients Geriatrics department we measured proteinuria (mg/dl)/creatinine (mg/dl) in urine (first miccion). Predictive variables were: baseline SAU and plasma creatinine; estimated GFR (abbreviated MDRD formula); recorded age, gender, baseline comorbidity (Charlson index), cardiovascular disease individualized, treatment and mortality Statistical analysis: SPSS15.0. Results: baseline SUA was normally distributed and its median was 5.85 mg/dl. We found not significant differences in levels of SUA by gender, history of diabetes mellitus, hypertension, diuretic use, heart disease, peripheral arterial disease or stroke. Patients with an history of heart failure had significantly higher SUA (7.00 +/- 1.74 vs. 5.90 +/- 1.71, P=0.031). 41 deaths occured during follow-up (15 men and 26 women): 15 general deterioration, 8 infections, 4 stroke, 4 tumors, 3 cardiovascular disease, 2 complications of fractures and 5 unknown. Patients with SUA higher than the median had significantly lower GFR and higher mortality at 5 years. In Cox' analysis for overall mortality (independent variables: age, gender, Charlson Index, history of heart failure, SUA, creatinine, proteinuria and GFR:MDRD), only SUA levels (HR:1,35; 1,17-1,56 p=0,000) were independently associated with mortality. Conclusions: In our study, levels of SUA are shown as independent risk factor for mortality in elderly patients.