The centre for Addiction and Mental Health (CAMH), Addiction Research Foundation in Canada has for many years treated clients for addictions to a variety of substances. This scientific poster presents a study in which this clinical database was used to select at random individuals beginning treatment in 1994 for the abuse of alcohol, cannabis, cocaine and all possible combinations of these substances, seven groups in all. Clients chosen were aged 20-59 years in 1994. About 80 people were chosen for each of the seven groups. A random sample of 522 control drivers of comparable age, sex and residence was used. Depending on the substance abuse group, 62-79% of clients had driving records. Women and clients abusing alcohol were less likely to have a driver record. Crash and conviction rates up to 1994 (pre-treatment) and after 1994 (post-treatment) were examined. There was a significant interaction for crashes before treatment between cocaine and cannabis, and only a modest effect for alcohol abuse. Crash rates post-treatment exhibited no interactions and no significant effects for these substances. Conviction rates all showed a decrease when comparing before and after 1994, which may be due to changes in enforcement. Interactions between cocaine and alcohol and cocaine and cannabis were both statistically significant for pre-treatment rates. Post-treatment, there was a statistically significant interaction involving all three substances. However, relative risks appeared to be more modest for clients where alcohol was involved than for clients where only cannabis or cocaine has been abused.
Abstract