Smoking of crack cocaine as a risk factor for HIV infection among people who use injection drugs

FRANÇAIS :
Cette étude menée par un centre britanno-colombien de recherche sur le sida, souligne le lien existant entre consommation de crack et transmission du VIH. Ces conclusions n'expliquent toutefois pas les raisons de ce fort taux de contamination. Les scientifiques estiment cependant que les fumeurs de crack sont peut-être susceptibles d'être davantage exposés au sida, notamment en ayant des relations sexuelles non protégées lors d'orgies au cours desquelles cette drogue est fortement consommée. Les chercheurs émettent également l'hypothèse qu'un taux supérieur à la normale de séropositifs fréquente cette communauté de drogués. De plus, les blessures autour de la bouche causées par l'utilisation de pipes en métal ou en verre pourraient rendre plus vulnérables au sida les fumeurs de crack, notamment lorsqu'ils se partagent ces pipes ou pratiquent le sexe oral, note l'étude.
ENGLISH :
Background: Little is known about the possible role that smoking crack cocaine has on the incidence of HIV infection. Given the increasing use of crack cocaine, we sought to examine whether use of this illicit drug has become a risk factor for HIV infection. Methods: We included data from people participating in the Vancouver Injection Drug Users Study who reported injecting illicit drugs at least once in the month before enrolment, lived in the greater Vancouver area, were HIV-negative at enrolment and completed at least 1 follow-up study visit. To determine whether the risk of HIV seroconversion among daily smokers of crack cocaine changed over time, we used Cox proportional hazards regression and divided the study into 3 periods: May 1, 1996-Nov. 30, 1999 (period 1), Dec. 1, 1999-Nov. 30, 2002 (period 2), and Dec. 1, 2002-Dec. 30, 2005 (period 3). Results: Overall, 1048 eligible injection drug users were included in our study. Of these, 137 acquired HIV infection during follow-up. The mean proportion of participants who reported daily smoking of crack cocaine increased from 11.6% in period 1 to 39.7% in period 3. After adjusting for potential confounders, we found that the risk of HIV seroconversion among participants who were daily smokers of crack cocaine increased over time (period 1: hazard ratio [HR] 1.03, 95% confidence interval [CI] 0.57-1.85; period 2: HR 1.68, 95% CI 1.01-2.80; and period 3: HR 2.74, 95% CI 1.06-7.11). Interpretation: Smoking of crack cocaine was found to be an independent risk factor for HIV seroconversion among people who were injection drug users. This finding points to the urgent need for evidence-based public health initiatives targeted at people who smoke crack cocaine. (Review' s abstract)