Risk factors in community-acquired chronic hepatitis C virus infection: a case-control study in Italy.

Abstract AIMS/METHODS: A case-control study was carried out in Italy to assess the risk factors associated with chronic hepatitis C virus infection. Five hundred consecutive chronic anti-hepatitis C virus positive cases and 500 sex and exactly age-matched anti-hepatitis C virus negative/HBsAg negative controls entered the study. Information was collected through an interviewer-administered questionnaire. The adjusted Odds Ratios linking hepatitis C virus infection and risk factors were estimated by conditional multiple logistic regression. Demographic and socio-economic characteristics were similar in cases and controls. Seventy-five percent of patients were aged over 40: males were prominent in the group < or = 40, while the number of females increased with age. RESULTS: As expected, drug addiction and blood transfusion emerged as independent risk factors: blood transfusion in all ages and in both sexes, drug addiction only in subjects under 41 years and mostly in males. Other risk factors independently associated with hepatitis C virus infection were: previous use of non-disposable needles, previous tuberculosis, and prolonged hospitalization before 1970. A history of sexually-transmitted diseases was not associated. CONCLUSIONS: This study shows that the great spread of hepatitis C virus in Italy may have occurred several years ago through parenteral routes which are not now operating. Modern hygienic and sanitation measures have significantly controlled exposure to the infection, which in the younger generations is confined to high-risk groups such as drug addicts.