Higher uric acid levels are associated with better functional recovery in elderly patients receiving cardiac rehabilitation

Abstract

Background and aims: Whether uric acid (UA) serves as risk factor for cardiovascular diseases or as antioxidant defense has not yet been completely clarified. In this study we investigated the effects of UA on functional recovery in patients receiving cardiac rehabilitation.

Methods and results: 306 patients, 209 men and 97 women, age range 25-87 years (mean 68 ± 11), performed the 6-min walk test (6mWT) before and after the rehabilitation, and the increase in walking distance was considered as the outcome measure of the study. Baseline UA serum levels ranged from 1.0 to 10.9 mg/dL (mean 5.2 ± 1.7). As there was a significant (p = 0.005) age*UA levels interaction, patients were divided into two subgroups, less then 65 years (n. 103, 68 men and 35 women, mean age 56 ± 9) and 65 years or more (n. 203, 141 men and 62 women, mean age 74 ± 5). After adjusting for relevant confounders, higher UA levels remained independent positive predictors of the increase in walking distance in older (p < 0.001) but not in younger patients (p = 0.807).

Conclusions: Our findings show an independent association of higher UA levels with better functional recovery after cardiac rehabilitation selectively in elderly patients, suggesting that higher UA levels might reflect the decline in antioxidant defenses that occurs with advancing age. Future studies aimed at understanding the several contradictions concerning UA should, probably, address the issue within this perspective.

Keywords: Antioxidants; Cardiac rehabilitation; Elderly; Functional recovery; Uric acid.