Background: Alcohol consumption is a well-known risk factor for elevated ALT levels, but the role of cigarette smoking is unclear.
Methods: We collected a cross-sectional sample of 6095 inhabitants 35 years or older in a community with hyperendemic hepatitis B and C virus infections. We assayed levels of serum alanine aminotransferase (ALT), hepatitis B surface antigen (HBsAg), and anti-hepatitis C virus antibody (anti-HCV). Multivariate logistic regression was performed to determine the factors for elevated ALT levels (> or =40 U/L) among people with different hepatitis infection statuses.
Results: Prevalence of elevated ALT levels in individuals who were seronegative for both infections or seropositive for HBsAg or anti-HCV was 3.9%, 11.1%, and 30.8%, respectively. Subjects with elevated ALT levels were more likely to be seropositive for anti-HCV, male, and seropositive for HBsAg; to drink alcohol; to smoke; and to have undergone blood transfusion (P<.05). An association was found between elevated ALT levels and the consumption of cigarettes and alcohol among anti-HCV-seropositive subjects. In multivariate logistic analyses, alcohol consumption (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.2-4.1) and smoking (OR, 1.8; 95% CI, 1.1-2.7) were significantly associated with elevated ALT levels among anti-HCV-seropositive subjects, but no such association was found among HBsAg-seropositive subjects. The odds of elevated ALT levels were 7 times higher (95% CI, 2.7-18.8) for the anti-HCV-seropositive patients who smoked 1 or more packs of cigarettes per day and frequently drank alcohol than for those who did not.
Conclusions: Smoking and alcohol consumption are independently associated with elevated ALT levels among anti-HCV-seropositive individuals but not among HBsAg-seropositive individuals. Patients who are seropositive for anti-HCV are strongly advised not to smoke and drink alcohol to reduce the possible risk for aggravating the liver dysfunction.