Serum uric acid levels in patients with multiple sclerosis: a meta-analysis

Background: Serum uric acid (UA), a natural scavenger of peroxynitrite, has been found to be of lower levels in patients with multiple sclerosis (MS) in some recent preliminary studies. Objective: To evaluate the correlation between serum UA levels and several clinical parameters of MS reliably. Methods: We surveyed studies on the serum UA levels and MS patients with comprehensive search and review of the references. A meta-analysis was performed to demonstrate the potential association between serum UA levels in MS patients and their clinical characteristics by random effects models. Results The serum UA levels were lower in patients with MS than in healthy controls (standardized mean difference (SMD) = -0.68; 95% confidence interval (CI): -0.82 to -0.55), as well as in other inflammatory neurological diseases (OINDs) (SMD = -0.45; 95% CI: -0.60 to -0.30). Similarly, the serum UA levels decreased in MS patients with clinical activity when compared to MS with clinical inactivity (SMD = -0.29; 95% CI: -0.48 to -0.10), as well as in relapsing-remitting MS (RRMS) patients with relapse in comparison to RRMS patients with remission (SMD = 0.64; 95% CI: 0.39 to 0.89). However, the results suggested that serum UA levels did not correlate with higher (or lower) expanded disability status scale (SMD = -0.09; 95% CI: -0.10 to 0.27) and magnetic resonance imaging (MRI) activity (SMD = -0.14; 95% CI: -0.13 to 0.41). In the subtypes of MS group, there were significant differences in serum UA levels between secondary progressive MS (SPMS) and RRMS (SMD = -0.34; 95% CI: 0.16 to 0.52), or primary progressive MS (PPMS) (SMD = -0.58; 95% CI: -0.89 to -0.27), but no significant difference between RRMS and PPMS (SMD = -0.18; 95% CI: -0.44 to 0.08). Conclusions: Our study suggests that UA is relevant to MS. Future research is needed to determine whether the administration of UA levels by inosine might be considered as a novel treatment strategy for MS.