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

INTRODUCTION

There is growing evidence of the role of serum uric acid (SUA) as a risk factor for cardiovascular and renal disease. We analysed the association between baseline SUA and overall mortality in a cohort of elderly patients followed prospectively for 5 years.

PATIENTS AND

METHODS

Eighty clinically stable patients, median age 83 years (range 69-97), 31.3% men, 35% diabetics, 83% hypertensives were randomly recruited at Geriatrics and Nephrology visits between January and April 2006 and followed for 5 years. We measured baseline SUA and serum creatinine and estimated glomerular filtration rate (GFR) with MDRD abbreviated. In Nephrology Department patients, we measured proteinuria in 24-hour urine and in Geriatrics department patients we measured proteinuria (mg/dl)/creatinine (mg/dl) in urine (first morning urine). Predictive variables were: baseline SUA and plasma creatinine; estimated GFR (abbreviated MDRD formula); and we recorded age, gender, baseline comorbidity (Charlson index), individualised cardiovascular treatment and mortality.

STATISTICAL ANALYSIS: SPSS15.0.

RESULTS

baseline SUA was normally distributed and its median was 5.85 mg/dl. We found no significant differences in levels of SUA by gender, history of diabetes mellitus, hypertension, diuretic drug use, heart disease, peripheral arterial disease or stroke. Patients with a history of heart failure had significantly higher SUA (7.00 ± 1.74 vs 5.90 ± 1.71, P=.031). Some 41 deaths occurred during follow-up (15 men and 26 women): 15 due to general deterioration, 8 due to infections, 4 due to stroke, 4 due to tumours, 3 due to cardiovascular disease, 2 due to complications of fractures and 5 due to unknown causes. Patients with SUA higher than the median had significantly lower GFR and higher mortality at 5 years. In the 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=.000) were independently associated with mortality.

CONCLUSIONS

In our study, levels of SUA are an independent risk factor for mortality in elderly patients.