BACKGROUND: While decriminalization of marijuana and medical marijuana laws provide a compassionate answer for treatment-related issues in patients' lives, they leave questions open as to the impact on other realms of life, like employment and safety.
METHODS: This is a case-control study comparing the proportion of marijuana positive urine specimens for post-accident verses random samples. The marijuana concentration of each sample underwent creatinine normalization to account for in vivo dilution. Any sample that tested positive for one or more substances other than marijuana was eliminated from the study. The prevalence of marijuana violations, the odds ratio and 95% confidence interval of accident involvement and the population attributable risk were calculated.
RESULTS: A two-by-two table was created with the remaining data. The data from the two-by-two table was used to calculate the odd ratio resulting in a value of 0.814 with the 95% confidence interval being between 0.625 and 1.060. The Fisher exact probability test generated a two-tailed p-value of 0.139. The subsequent population attributable risk was found to be -1.83%. These findings fail to reject the null hypothesis.
CONCLUSIONS: This study failed to demonstrate a statistically significant difference between the numbers of laboratory positive marijuana urine drug tests for a group of random drug tests compared to a group of post-accident drug tests.