Dose-response meta-analysis on urate, gout, and the risk for Parkinson's disease.

The relationship between Parkinson's disease (PD) and urate or gout has attracted significant interest in recent years, but the results were conflicting. This dose-response meta-analysis aimed to estimate the correlation between urate levels or gout and the risk for PD. The Embase, PubMed, and Medline databases were searched for studies that investigated the relationship between the risk for PD and urate levels or gout. Random-effects or fixed-effects models were used to obtain pooled relative risks (RRs) and corresponding 95% confidence intervals (CIs). Fifteen studies, involving 449,816 participants and 14,687 cases in total, were included in the meta-analysis. High serum urate levels were associated with decreased risk for PD (RR 0.44 [95% CI 0.32-0.55]). Subgroup analysis according to sex revealed a neuroprotective effect of high urate levels against PD among females (0.68 [95% CI 0.43-0.93]) and males (0.49 [95% CI 0.34-0.64]). The risk for PD was lowered by 6% (0.94 [95% CI 0.90-0.98]) for each 1 mg/dl increase in serum urate level and reduced by 13% (0.87 [95% CI 0.80-0.95]) with each 2 mg/dl increase in serum urate level. However, gout was not closely correlated with the risk for PD (0.97 [95% CI 0.85-1.09]). Higher serum urate levels reduced the risk for PD, which was decreased by 6% (relative risk reduction) for each 1 mg/dl increase in serum urate levels. And the results indicated that urate may exert protective effects against the development of PD.