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


CONCLUSIONS
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.
DeBeck
Kora
K
British Columbia Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC.
Kerr
Thomas
T
Li
Kathy
K
Fischer
Benedikt
B
Buxton
Jane
J
Montaner
Julio
J
Wood
Evan
E
D000328:Adult; D017677:Age Distribution; D001955:British Columbia / Q000453:epidemiology; D019970:Cocaine-Related Disorders / Q000175:diagnosis / Q000453:epidemiology*; D015331:Cohort Studies; D015897:Comorbidity; D016001:Confidence Intervals; D016578:Crack Cocaine / Q000009:adverse effects*; D005260:Female; D015658:HIV Infections / Q000175:diagnosis / Q000453:epidemiology*; D006679:HIV Seropositivity / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D017678:Sex Distribution; D015819:Substance Abuse, Intravenous / Q000175:diagnosis / Q000453:epidemiology*; D016019:Survival Analysis; D014505:Urban Population; D055815:Young Adult
D016578:Crack Cocaine