Su TH, Yang HC, Tseng TC, et al. - Researchers conducted multivariable Cox proportional hazards regression analyses to explore the connection between chronic hepatitis C (CHC) and parkinsonism and the efficacy of antiviral therapy. Patients with and without CHC, patients receiving pegylated interferon-based antiviral therapy, and those without such therapy were matched by age, sex and comorbidities by propensity scores, and followed for new diagnoses of parkinsonism and Parkinson disease (PD) using the National Health Insurance Research Database of Taiwan from 2004 to 2012. A total of 49,342 CHC patients were matched with 49,342 non-CHC patients. Findings suggested an association of CHC infection with an increased risk of parkinsonism or PD. A decreased risk of parkinsonism or PD was correlated with antiviral therapy against CHC.