Crack cocaine smokers who turn to drug injection: characteristics, factors associated with injection, and implications for HIV transmission. The Multicenter Crack Cocaine and HIV Infection Study Team.

A survey of 1220 street-recruited crack cocaine smokers revealed that crack smokers may turn to drug injection to ease crack withdrawal. Crack smokers who later injected tended to smoke crack more heavily and for longer periods than those who did not inject. The initiation of injection was significantly associated with ever snorting heroin (prevalence ratio [PR] = 3.4, 95% confidence interval [CI] = 2.0-5.9) or snorting heroin specifically while smoking crack (PR = 2.3, 95% CI = 1.3-4.0), suggesting that snorted heroin use may mediate the transition to injection among crack smokers. Programs to prevent and treat crack dependence may prevent later injection and injection-related infections including HIV.