Trends in detection rates of risky marijuana use in Colorado health care settings.

BACKGROUND: Over the past several years, many states, including Colorado, have approved medical marijuana legislation. There is concern that increased access to and visibility of medical marijuana may lead to harmful use.

METHODS: This study examined changes in patients' marijuana use in 12 health care settings through a statewide screening, brief intervention, and referral to treatment (SBIRT) initiative.

RESULTS: Beginning in 2009, the odds of screening positive for risk-prone marijuana use significantly increased, coinciding with dramatic increases in use of Colorado's medical marijuana program. Young males were most likely to screen positive. Among users, there was a small, statistically significant increase in severity of use over time.

CONCLUSIONS: Findings suggest that health care providers may be serving increasing numbers of patients using marijuana for medical or recreational purposes.