Abstract

Background: Cannabis may have adverse consequences for cardiovascular health. Colorado decriminalized cannabis on November 2012 and retail sales of cannabis began in January 2014. We examined whether the overall rate of hospitalizations and hospitalizations for acute cardiovascular events (ACE) increased in Colorado after legalization.

Hypothesis: We hypothesized that the rates of all-cause hospitalizations and ACE would increase post legalization of recreational cannabis.

Methods: The State Inpatient Database (SID) for Colorado, available through Healthcare Cost and Utilization Project was analyzed using interrupted time-series methods to assess whether increases in sales of marijuana affected the rates of overall hospitalization and hospitalization for ACE, post legalization of cannabis. The time analyzed included January 2008 through September 2015. We ended the data of analysis on October 1 2015, because ICD-10 codes were implemented in October 2015. The primary outcome, rate of hospitalizations, was measured by total unique inpatient admissions within the SID for each monthly time period. The secondary outcome, ACE, was identified using ICD-9 diagnostic codes for myocardial infarction (410), stroke (430, 431, 433, 434, 436), and ICD-9 procedure codes for coronary artery bypass surgery (36.1x), and percutaneous coronary intervention (36.0x, 0.66). In the interrupted time series regression models we accounted for seasonality and consumption of cigarettes and alcohol using a proxy of sales tax collected each month for cigarettes and alcohol. In the ACE models, we controlled for seasonality, sales of cigarettes and average monthly air temperature. We also examined the effect of legalization on the same outcomes in men and women and different age subgroups.

Results: While overall rates of hospitalizations decreased somewhat over the study period, there was no statistically significant difference in hospitalizations rates, neither in the regression intercept (for immediate change) (p=0.94) or slope (p=0.97), after the legalization of recreational cannabis. Similarly, ACE rates decreased over the time frame, but there were no significant changes in rate intercept (p=0.80) or slope (p=0.71) post legalization. The subgroup analyses by age category and gender for hospitalizations and ACE also showed no significant differences in rates pre and post legalization.

Conclusions: We found no evidence that overall hospitalizations and hospitalizations for ACE increased due to legalizing recreational cannabis in Colorado. A limitation of our study was that Colorado had already implemented a medical marijuana program in 2000. Recreational legalization may not have led to a significant increase in users. Future studies should examine the link between legalization and cardiovascular events in other states with a different trajectory of legalization.