Prevalence of antibodies to hepatitis C in a population of intravenous drug users in Valencia, Spain, 1990-1992

Background. Hepatitis C has been related to other viral diseases such as the human immunodeficiency virus infection (HIV) or hepatitis B (HBV). The objective of this study was to estimate the prevalence and determinants of antibodies to hepatitis C virus (HCV) in intravenous drug users (IVDU) in Valencia (Spain) and to compare the seroprevalence between the HCV, HIV and HBV in this high risk group. Methods. A cross-sectional study was conducted in a sample of 1056 current IVDU from the Valencia area who attended the city's AIDS information Centre between January 1990 and December 1992. Information on sociodemographic, sexual behaviour, and drug use variables was collected by means of a structured questionnaire, Antibodies to HCV, HIV and HBV were assayed by ELISA test. Results. The seroprevalence of HCV for the whole period was 85.5% (95% confidence interval [CI] : 83.2-87.5%), ranging from 76.5% in 1990 (95% CI : 71.9-81.1%) to 87.8% in 1992 (95% CI : 82.5-93.1%). Year of testing and prevalence of HBV markers showed an independent association with HCV seroprevalence. When only IVDU aged <25 years were analysed, sharing of needles also appeared as an independent determinant. Of those IVDU with less than one year of addiction, 69% were HCV seropositive compared with 41% for HBV and 14% for HIV. Conclusions. Intravenous drug users in Valencia showed one of the highest reported hepatitis C seroprevalences (85.5%). A more efficient parenteral transmission of hepatitis C virus than HBV or HIV is suggested.