Objective To assess the effect of cannabis legalisation on health effects and healthcare utilisation in Colorado (CO), the first state to legalise recreational cannabis, when compared with two control states, New York (NY) and Oklahoma (OK).
Design We used the 2010 to 2014 Healthcare Cost and Utilisation Project (HCUP) inpatient databases to compare changes in rates of healthcare utilisation and diagnoses in CO versus NY and OK.
Setting Population-based, inpatient.
Participants HCUP state-wide data comprising over 28 million individuals and over 16 million hospitalisations across three states.
Main outcome measures We used International Classification of Diseases-Ninth Edition codes to assess changes in healthcare utilisation specific to various medical diagnoses potentially treated by or exacerbated by cannabis. Diagnoses were classified based on weight of evidence from the National Academy of Science (NAS). Negative binomial models were used to compare rates of admissions between states.
Results In CO compared with NY and OK, respectively, cannabis abuse hospitalisations increased (risk ratio (RR) 1.27, 95% CI 1.26 to 1.28 and RR 1.16, 95% CI 1.15 to 1.17; both p<0.0005) post-legalisation. In CO, there was a reduction in total admissions but only when compared with OK (RR 0.97, 95% CI 0.96 to 0.98, p<0.0005). Length of stay and costs did not change significantly in CO compared with NY or OK. Post-legalisation changes most consistent with NAS included an increase in motor vehicle accidents, alcohol abuse, overdose injury and a reduction in chronic pain admissions (all p<0.05 compared with each control state).
Conclusions Recreational cannabis legalisation is associated with neutral effects on healthcare utilisation. In line with previous evidence, cannabis liberalisation is linked to an increase in motor vehicle accidents, alcohol abuse, overdose injuries and a decrease in chronic pain admissions. Such population-level effects may help guide future decisions regarding cannabis use, prescription and policy.
- healthcare utilization
- health policy
- cannabis legalization
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Contributors FND and GMM had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. FND and GMM were responsible for the study concept and design. All authors (FND, EV, TAD, MJP, JEO, GN, KA, CDF, ESL, SMF, DSK and GMM) contributed to data acquisition, analysis and interpretation. EV, GN and GMM completed the statistical analysis. FND and GMM drafted the manuscript and were responsible for the critical revision of the manuscript for important intellectual content. GMM obtained funding for the study. All authors contributed to the administrative, technical and material support for the study and approved the final version of the manuscript.
Funding This work was supported by the Agency for Healthcare Research and Quality (AHRQ) and Health Care Information (HCI) Division of the Oklahoma State Department of Health.
Competing interests None declared.
Ethics approval Ethical approval to use de-identified HCUP data was obtained from the University of California, San Francisco Committee on Human Research.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data consist of de-identified participant data (ie, ICD-9 admission diagnoses) available from the Healthcare Cost and Utilisation Project (HCUP) for a fee. Information about how to obtain the data and for what time period can be found at: https://www.hcup-us.ahrq.gov/
Patient consent for publication Not required.
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