Hepatitis C virus infection and risk of Parkinson's disease: a systematic review and meta-analysis

Background/objectiveHepatitis C virus (HCV) infection is one of the most common infections worldwide. Recent epidemiologic studies have suggested that patients with HCV infection might be at an increased risk of Parkinson's disease. However, the data on this relationship remain inconclusive. This meta-analysis was conducted with the aim to summarize all available evidence.Patients and methodsA literature search was performed using MEDLINE and EMBASE database from inception to May 2017. Studies that reported relative risks, odd ratios (ORs), or hazard ratios comparing the risk of Parkinson's disease among HCV-infected patients versus participants without HCV infection were included. Pooled OR and 95% confidence interval were calculated using a random-effect, generic inverse variance method.ResultsOf 468 studies, five studies with 323974 participants met our eligibility criteria and were included in the analysis. We found a higher risk of Parkinson's disease among patients with chronic HCV infection compared with participants without HCV infection with the pooled OR of 1.35 (95% confidence interval: 1.19-1.52). The statistical heterogeneity of this study was insignificant (I-2=3%). The main limitation of this meta-analysis was the limited accuracy of diagnosis in the primary studies as they were coding-based studies.ConclusionThis study demonstrated a higher risk of Parkinson's disease among HCV-infected patients. Further studies are required to clarify how this risk should be addressed in the clinical picture.