Prevalence of marijuana use among trauma patients before and after legalization of medical marijuana: The Arizona experience.

In recent years, marijuana has become legal for use in many states, for either medicinal or recreational purposes. The primary objective is to determine if legalization of medical marijuana is associated with an increased use among trauma patients. Prospective observational study included three periods; (pre-legalization; period 1); legal to grow for medicinal purposes but no dispensaries open (period 2); and legal to purchase medicinal marijuana in a dispensary (period 3). The study included all adult trauma patients presenting to an urban level I trauma center in Phoenix, AZ. The prevalence of use (as defined by positive urine drug screen or self-reporting) in each time period was determined and compared using two sample tests of proportion. Confidence intervals for prevalence (self-reporting only) were compared with published age matched data from the same geographical region of the general population. The prevalence of marijuana use increased significantly from pre-legalization (period 1) to post legalization (periods 2 and 3), but there was no significant change between the two post legalization periods. After controlling for age and sex, the odds of being marijuana positive post-legalization vs. pre-legalization was 1.36,  = 0.006 95%CI [1.09-1.7]. Overall, the prevalence of marijuana among trauma patients was nearly four-fold higher than the population as a whole in the same geographic region. Patients who use marijuana are more likely to use cocaine or amphetamine (OR 2.31; 95% CI 1.86-2.89) or had an ethanol level above 80 mg/dL (OR 1.57; 95% CI 1.32-1.87). The legalization of medicinal marijuana is associated with significantly increased prevalence among trauma patients. It appears that legalization, rather than the convenience of dispensaries, is associated with an increase in use.