Cannabis use in relation to illicit drug use and health problems among opiate misusers in treatment

The study investigated cannabis use among 200 opiate misusers attending out-patient treatment services at two sites. Three groups were classified according to the frequency of their cannabis use in the previous month; 40.5% were non-users, 40% daily users and the remaining 19.5% were classified as occasional users (they had used on between 1 and 29 days in the previous month). Non-users of cannabis had used heroin in the previous month on more occasions than either daily or occasional users (p < 0.001). Non-cannabis users also reported the highest average frequencies of use of alcohol (p < 0.01) and crack cocaine (p < 0.05). In contrast, daily users of cannabis reported more symptoms of anxiety (p < 0.01) and depression (p < 0.01) than either of the other groups. Finally, daily cannabis users were more likely to report dietary problems than either occasional users or non-users of cannabis. While cannabis use is highly prevalent among opiate misusers in treatment, its relationship to treatment outcome is complex and requires greater research scrutiny.