Identifying the association between Physical Activity and HCV infection status: An observational study and Mendelian randomization analysis

Purpose To investigate the association and causality between physical activity and hepatitis C virus (HCV) infection. Methods In this cross-sectional study, we conducted a bidirectional two-sample Mendelian Randomization (MR) analysis using data from the GWAS database. The analytic population was divided into three categories based on hepatitis C virus infection outcomes, and statistical differences were analyzed with covariates. Additionally, Restricted Cubic Spline (RCS) analysis was applied to examine the nonlinear relationship between physical exercise and hepatitis C virus infection. Instrumental variables were selected with a threshold of P < 5*10⁻⁸, and the causal relationships were assessed using IVW, MR-Egger, Weighted Median, Weighted Mode, and Simple Mode methods. Cochran's Q test was used to assess and exclude data heterogeneity. Results In the population data analysis, the moderate-to-vigorous work (MVW) variable showed a significant association with HCV infection (p = 0.006). MVW demonstrated a positive association with HCV infection (OR = 2.46, 95% CI = 1.02–5.92). RCS analysis indicated that the risk of HCV infection significantly increased when MVW exceeded 810 minutes per week. MR analysis indicated that MVW had a unidirectional effect on HCV infection (IVW model: OR = 1.366, 95% CI: 1.121–1.663, p = 0.002), and heterogeneity was excluded from the analysis. Conclusions In the context of HCV infection, the primary factor influencing risk is not the duration of physical activity, but the type. High-intensity physical activity significantly elevates the risk of HCV infection. It may be prudent to manage work hours responsibly to minimize physical strain.