A recent study published in the Canadian Medical Association Journal found that smoking crack cocaine is a risk factor for HIV infection amongst injection drug users.

A previous study conducted in the United States had evaluated inner-city young adults and found that smoking of crack cocaine was associated with HIV infection. Nevertheless, in Canada, knowledge about the impact of crack cocaine use on HIV infection has remained limited. Despite high rates of crack cocaine use (as high as 86 percent in Vancouver), public health programs directed at this group of drug users have remained controversial.

According to Dr. Evan Wood, one of the researchers involved in this study, “Evidence-based responses to crack cocaine are needed. The U.S. has tried law enforcement as a strategy but this has failed to reduce the use and availability of crack cocaine and has filled U.S. prisons with non-violent drug offenders. Alternatives to this approach need to be explored.”

Due to the limited amount of information available on this issue, this study sought to discover whether crack cocaine use was a risk factor for HIV infection amongst Canadians.

The researchers studied 1048 injection drug users, all of whom were participants of the Vancouver Injection Drug Users Study. Patients were HIV-negative at the time of enrollment, and had admitted to using illicit drugs at least once in the month prior to enrollment. The study was divided into three time periods, allowing researchers to determine whether the risk for HIV infection increased over time.

Of the 1048 participants enrolled in the study, 137 were infected with HIV upon follow up. The average proportion of individuals who reported smoking crack cocaine on a daily basis also increased from 11.6 percent in the first period to 39.7 percent in the third period.

Cocaine is an addictive stimulant drug that can be administered through smoking, injecting, or snorting. “Crack” cocaine is a form of cocaine that has been processed into rock crystals. These crystals are heated, and the vapors are then smoked through a pipe.

Risk factors that were not measured in this study relate to the method of administering crack cocaine. Crack cocaine smokers generally use metal or glass pipes, which are known to cause wounds in the mouth. This may make users more susceptible to HIV transmission when pipes are shared amongst several users, or through sexual activities such as oral sex. These risk factors were not measured however, as data was not collected on oral wounds or the sharing of pipes.

Another unmeasured confounding factor relates to the participants’ social networks, as crack cocaine users may be more likely to socialize with HIV-positive individuals. Also, it is possible that during crack cocaine binge use, individuals in the study may have engaged in risky sexual behavior as a result of the psychological effects of the drug.

According to data provided in the study, many of the participants had engaged in sex work. Moreover, more than half of the female participants had engaged in sex work, whereas less than ten percent of the male participants had done so. These data suggest the need for developing special health programs focused on women.

“Women and men face unique health challenges and interventions should be tailored where possible to men and women’s unique health needs,” said Dr. Wood.

Because these factors were not measured in the study, they pose limitations on the results. However, these results show that smoking crack cocaine serves as an independent risk factor for the contraction of HIV. Such findings indicate a pressing need for public health programs that focus on crack cocaine users.

For more information, please see the Canadian Medical Association Journal Web site.