Injury risk associated with cannabis and cocaine use.

The purpose of this paper is to review the results and limitations of studies of injury risks associated with cannabis and cocaine use. Three types of fatal and non-fatal injuries are considered: injuries due to collisions, intentional injuries and injuries in general. Four types of studies were reviewed: (I) laboratory studies, (II) descriptive and analytic epidemiological studies on the prevalence of cannabis or cocaine use through drug testing of those injured, (III) studies of non-clinical samples, and (IV) studies of clinical samples of drug users. The research that utilized drug tests showed similar proportions testing positive for cannabis in fatal and non-fatal injury groups, and for collisions, violence and injuries in general. By contrast, large differences in the average proportions testing positive for cocaine were found among these same injury groups. For example, 28.7% of people with intentional injuries (primarily homicides) tested positive for cocaine, while 4.5% of injured drivers tested positive. Studies of non-clinical samples have shown that both cannabis and cocaine use are related to intentional injuries and injuries in general. Results indicate higher risk for all types of injuries among cannabis and cocaine clients in treatment. Strengths and limitations of the different types of studies are discussed. More rigorous studies are needed which should focus on ruling out alternative explanations for relationships between drug use and injuries.