Significant reductions of HIV prevalence but not of hepatitis C virus infections in injection drug users from metropolitan Barcelona: 1987-2001

Objectives: To characterize trends from 1987 to 2001 in the prevalence of HIV and HCV infections among 2219 injection drug users (IDUs) starting treatment for substance abuse in two large hospitals in metropolitan Barcelona. Methods: The study population comprised IDUs with HIV tests completed from 1987 to 2001 and admitted for detoxification. Testing for HCV started in 1991 (n=1132). Characterization of temporal trends was carried out using logistic regression methods. Stratification was used to describe possible heterogeneities of the temporal trends. Results: The overall prevalence of HIV, HCV, and HBV (HBsAg+) was 55%, 88%, and 7%, respectively. Adjusted by duration of IDU, sex, and age at initiation, the prevalence of HIV infection declined significantly (p<0.001) from 1989 to 2004. The substantially higher prevalence of HCV showed a decline (p=0.065) of lesser magnitude. The decline of HIV infection was consistently observed among those with duration of IDU of less than 10 years. In turn, the decline of HCV was restricted to those with short duration of IDU (<4 years) because the prevalence of HCV infection was close to 100% for durations longer than 4 years in all calendar periods. Conclusions: Preventive interventions and treatment for substance abuse might have contributed to the waning of the HIV epidemic in Spain. However, the extremely high levels of HCV infection and the underlying prevalence of HIV might lead to a large health burden of liver disease.