Alcohol has no effect on hepatitis C virus replication: a meta-analysis

Background: Patients with chronic hepatitis C virus (HCV) infection who consume large quantities of alcohol have more severe liver disease compared with HCV patients without a history of alcohol consumption. The mechanism by which alcohol worsens HCV related liver disease is not properly understood. One possibility is that alcohol stimulates HCV replication, and the present meta-analysis was performed to examine this issue. Methods: The effect of alcohol on viral titres was assessed in three ways: comparison of the heaviest drinkers with non-drinkers; effect of graded doses of alcohol; and effect of abstinence in the same individual. Results: A total of 14 studies were identified. Comparison of patients with the highest alcohol use with the abstinent group showed a significant association with viral load in three studies, five studies had a positive direction, while the remaining four studies found a negative relationship. Analysis of the combined results showed no association between alcohol consumption and virus levels ( p = 0.29). Assessment of graded doses of alcohol also showed no significant difference between non-drinkers and moderate drinkers ( p = 0.50), between non-drinkers and heavy drinkers ( p = 0.35), or between moderate drinkers and heavy drinkers ( p = 0.32). Five studies examined the influence of abstinence on viral titres but none provided sufficient data for statistical analysis. Conclusions: The present study has failed to show an association between alcohol use and HCV viral titres. These observations raise the possibility that the hepatic damage caused by alcohol and HCV may be purely additive, involving different mechanisms and pathways.