Determinants of HIV-1 infection in intravenous drug users in Valencia, Spain, 1987-1991.

From 1987 through 1991, 2687 intravenous drug users recruited at three AIDS information centres in the Region of Valencia (Spain) were interviewed about drug use and sexual behaviour and subsequently tested for HIV-1 antibody. The overall seroprevalence was high, 50% (95% confidence interval [CI]: 41.8-51.9%). There were no differences by gender, but HIV-1 infection was related to older age and city of residence. After adjustment by means of logistic regression age (odds ratio [OR] = 1.80), sharing of injection equipment (OR = 2.16), duration of addiction (OR = 6.59) and prostitution (OR = 1.77) were significantly associated with HIV-1 prevalence. High educational level was inversely related to HIV-1 status (OR = 0.43) and a decreasing trend of prevalence with time was observed.