The harm reduction approach and risk factors for human immunodeficiency virus (HIV) seroconversion in injecting drug users, Amsterdam.

To assess risk factors for seroconversion to human immunodeficiency virus, the authors studied a cohort of human immunodeficiency virus-seronegative injecting drug users in Amsterdam, the Netherlands, between December 1985 and November 1991. The behaviors of 31 seroconverters were compared with those of 202 seronegative injecting drug users (controls). Three independent risk factors for seroconversion were found in logistic regression: 1) living greater than 10 years in Amsterdam (odds ratio (OR) = 2.45, 95% confidence interval (CI) 1.09-5.53); 2) first injection less than or equal to 2 years ago (OR = 3.43, 95% CI 1.20-9.81); and 3) injecting mainly at home (OR = 0.39, 95% CI 0.18-0.88). No evidence was found that receiving daily methadone treatments at methadone posts and obtaining new needles/syringes via the exchange program were protective. However, the data suggest that exchanging needles may have been protective at the start of this program. Influencing injecting drug users to modify behavior to prevent new infections appears to be very difficult, and it may, therefore, be important to increase preventive efforts targeted at the sexual partners of injecting drug users.