Trends in cannabis urine drug screen testing in Colorado’s largest health system: a retrospective cohort study

Colorado was the first state in the United States to legalize recreational cannabis, which provides a unique opportunity to evaluate cannabis urine drug screen (UDS) testing trends in a large healthcare system in response to that policy. This study examined how testing rates and positivity evolved over time and whether testing patterns varied by demographic factors. In this retrospective cohort study, we analyzed all University of Colorado Health visits from 2008 to 2022 using electronic medical record data. We assessed group comparisons with Chi-squared tests and t-tests and demographic predictors of UDS testing using multivariable log binomial models. From 2008 to 2022, the positivity rate for cannabis among UDSs rose from 14% in 2008 to 30% in 2015, then plateaued. The proportion of visits with cannabis testing declined from 0.25% to 0.04%. Younger patients, males, and individuals identifying as Black, Hispanic, or American Indian were more likely to be tested than their counterparts, with notable racial and ethnic disparities. Despite rising cannabis positivity rates, testing frequency declined. Persistent demographic disparities in testing raise concerns about potential bias, especially in the absence of documented differences in use across groups. Future work should examine indications for cannabis urine drug screen testing and how results influence clinical care.