Background. Tobacco smoking has been shown to be an independent risk factor for liver fibrosis in hepatitis C virus (HCV) infection in some cross-sectional studies. No longitudinal study has confirmed this relationship, and the effect of tobacco exposure on liver fibrosis in human immunodeficiency virus (HIV)-HCV coinfected individuals is unknown. Methods. The study population consisted of participants from the Canadian Co-infection Cohort study (CTN 222), a multicenter longitudinal study of HIV-HCV coinfected individuals from 2003 to 2014. Data were analyzed for all participants who did not have significant fibrosis or end-stage liver disease (ESLD) at baseline. The association between time-updated tobacco exposure (ever vs nonsmokers and pack-years) and progression to significant liver fibrosis (defined as an aspartate-to-platelet ratio index [APRI] ≥1.5) or ESLD was assessed by pooled logistic regression. Results. Of 1072 participants included in the study, 978 (91%) had ever smoked, 817 (76%) were current smokers, and 161 (15%) were previous smokers. Tobacco exposure was not associated with accelerated progression to significant liver fibrosis nor with ESLD when comparing ever vs never smokers (odds ratio [OR] = 1.06, 95% confidence interval [CI], 0.43-1.69 and OR = 1.20, 95% CI, 0.21-2.18, respectively) or increases in pack-years smoked (OR = 1.05, 95% CI, 0.97-1.14 and OR = 0.94, 95% CI, 0.83-1.05, respectively). Both time-updated alcohol use in the previous 6 months and presence of detectable HCV ribonucleic acid were associated with APRI score ≥1.5. Conclusions. Tobacco exposure does not appear to be associated with accelerated progression of liver disease in this prospective study of HIV-HCV coinfected individuals.
Keywords: HCV; HIV; cohort study; liver disease; tobacco.