October 27, 2009
Daily smoking of crack cocaine is an independent risk factor for HIV infection, according to a nine-year study involving 1,048 injection drug users (IDUs) in Vancouver's Downtown Eastside.
When the study began in 1996, only 11.6 percent of the IDUs smoked crack daily, and researchers saw no evidence that smoking the drug was associated with HIV incidence. The mean proportion of IDUs smoking crack daily increased steadily to 39.7 percent during the study's later period (Dec. 1, 2002 -- Dec. 30, 2005), and evidence of crack smoking as an HIV risk factor became noticeable and grew over time.
After adjusting for potential confounders, the daily crack smokers were four times more likely to become HIV-infected than those who smoked less or no crack at all. HIV may be spread when crack smokers have mouth or lip wounds and share their pipes with HIV-positive users, researchers hypothesized, while adding that the true mode of transmission was not known. Engaging in unprotected sex during drug binges could also be a factor, they said. Downtown Eastside has the highest HIV/AIDS rate in Canada.
The study's finding "points to the urgent need for evidence-based public health initiatives targeted at people who smoke crack cocaine," the study authors concluded. "The current approach simply isn't working," said lead author Dr. Evan Wood of the British Columbia Center for Excellence in HIV/AIDS. Possible interventions include providing crack cocaine smokers with facilities where smoking would be medically supervised and treatment information would be accessible, some research suggests.
The full report, "Smoking of Crack Cocaine as a Risk Factor for HIV Infection Among People Who Use Injection Drugs," was published in the Canadian Medical Association Journal (2009;doi:10.1503/cmaj.082054).