LAUSR

The availability of direct-acting antiviral (DAA) therapies for hepatitis C virus (HCV) has led WHO to advocate for the elimination of HCV. However, a 2017 Cochrane review suggests that DAA treatment might not improve morbidity and mortality in people living with HCV: trials have shown no benefit on these endpoints, despite a sustained virological response. Stefan Wiktor and John Scott (July 8, p 107) state that longer term observational data are needed to assess mortality in people receiving DAA treatment for HCV. Previous research into HIV suggests that there is another reason that scaling up DAA treatment, as advocated by WHO, might not fully achieve the anticipated reductions in premature mortality in people living with HCV. Highly active antiretroviral therapy decreased HIVrelated deaths, but was accompanied by an increase in deaths from non-HIVrelated causes, partly because of the high prevalence of smoking in people living with HIV. Smoking prevalence in people living with HCV appears to be even higher than in people living with HIV, with estimates of up to 67%. This high prevalence of smoking could mean that any reductions in HCV-related morbidity and mortality produced by DAAs are partially offset by tobacco-related morbidity and mortality. Research into the health implications of smoking in chronic HCV is in its infancy, but suggests that HCV, like HIV, increases susceptibility to tobacco-related diseases. For example, smoking is strongly associated with increased liver fibrosis in people with HCV, and might affect development of cirrhosis. Smoking and HCV are independent predictors of cardiovascular disease and hepatocellular carcinoma, and a meta-analysis of six studies showed a multiplicative interaction index score of 1·60 (95% CI 1·16–2·20) between tobacco smoking and chronic HCV and risk of hepatocellular carcinoma. The rollout of national DAA treat ment programmes creates an important opportunity to provide evidence-based treatment of tobacco dependence to people living with HCV. Copious evidence shows the effectiveness of behavioural and pharmacological treatments for tobacco dependence, which can be delivered in routine health care. These treatments need to target the high smoking prevalence in people living with HCV to avoid reducing the potential improvements in health and longevity that are made possible by advances in DAA treatment.