Introduction
Cannabis legalization in Colorado resulted in increased cannabis-associated healthcare utilization. Our objective was to examine co-occurrence of cannabis and mental health diagnostic coding in Colorado emergency department (ED) discharges and replicate the study in a subpopulation of ED visits where cannabis involvement and psychiatric diagnosis were confirmed through medical review.

Methods
We collected state-wide ED ICD-9-CM diagnoses from the Colorado Hospital Association and a subpopulation of ED visits from a large, academic hospital from 2012 to 2014. Diagnosis codes identified visits associated with mental health and cannabis. Codes for mental health conditions and cannabis were confirmed by manual records review in the academic hospital subpopulation. Prevalence ratios of mental health ED discharges were calculated to compare cannabis-associated visits to those without cannabis. Rates of mental health and cannabis-associated ED discharges were examined over time.

Results
State-wide data demonstrated a five-fold higher prevalence of mental health diagnoses in cannabis-associated ED visits (PR: 5.35, 95% CI: 5.27-5.43) compared to visits without cannabis. The hospital subpopulation supported this finding with a four-fold higher prevalence of psychiatric complaints in cannabis attributable ED visits (PR: 4.87, 95% CI: 4.36-5.44) compared to visits not attributable to cannabis. State-wide rates of ED visits associated with both cannabis and mental health significantly increased from 2012 to 2014 from 224.5 to 268.4 per 100,000 (p<0.0001).

Conclusions
In Colorado, the prevalence of mental health conditions in ED visits with cannabis-associated diagnostic codes is higher than in those without cannabis. There is a need for further research determining if these findings are truly attributed to cannabis or merely coincident with concurrent increased use and availability.

Katelyn E Hall MPH, Andrew A. Monte MD, Tae Chang BA, Jacob Fox BA, Cody Brevik BS, Daniel I Vigil MD MPH, Mike Van Dyke PhD CIH, Katherine A. James PhD MSPH
Academic Emergency Medicine, 24 February 2018
DOI: 10.1111/acem.13393
http://onlinelibrary.wiley.com/doi/10.1111/acem.13393/abstract

Mental Health-Related Emergency Department Visits Associated with Cannabis in Colorado – 2018