State marijuana laws and opioid overdose mortality

Stanford Chihuri,Guohua Li

doi:10.1186/s40621-019-0213-z

Stanford Chihuri, Guohua Li

Open Access

https://doi.org/10.1186/s40621-019-0213-z

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Abstract

BackgroundThe opioid epidemic in the United States is a national public health crisis. In recent years, marijuana legalization has been increasingly adopted by state governments as a policy intervention to control the opioid epidemic under the premise that marijuana and opioids are substitutive substances. The purpose of this systematic review is to synthesize the empirical evidence regarding the impact of state marijuana laws on opioid overdose mortality and other opioid-related health outcomes.MethodA comprehensive search of the research literature in 18 bibliographic databases returned 6640 records, with 5601 abstracts reviewed, 29 full text articles screened for eligibility, and 16 eligible studies included in the systematic review. Comprehensive Meta-Analysis software was used to generate summary estimates, forest plots, funnel plots, and heterogeneity statistics.ResultsOf the 16 eligible studies, 4 assessed the association of state marijuana law status with opioid overdose mortality, 7 with prescription opioids dispensed, and the remaining with nonmedical use and opioid-related hospitalizations. Random effects modeling based on pooled data revealed that legalizing marijuana for medical use was associated with a statistically non-significant 8% reduction in opioid overdose mortality (95% confidence interval: − 0.21 to 0.04; p = 0.201) and a 7% reduction in prescription opioids dispensed (95% confidence interval: − 0.13 to − 0.01; p = 0.017). Legalizing marijuana for recreational use was associated with an additional 7% reduction in opioid overdose mortality in Colorado and 6% reduction in opioid prescriptions among fee-for-service Medicaid and managed care enrollees.ConclusionsLegalizing marijuana might contribute to a modest reduction in opioid prescriptions. Evidence about the effect of marijuana legalization on opioid overdose mortality is inconsistent and inconclusive. If any, the effectiveness of state marijuana laws in reducing opioid overdose mortality appears to be rather small and limited to states with operational marijuana dispensaries. It remains unclear whether the presumed benefit of legalizing marijuana in reducing opioid-related harms outweighs the policy’s externalities, such as its impact on mental health and traffic safety.

Highlights

Drug overdose is the leading cause of injury mortality in the United States (Ahmad et al 2018; Centers for Disease Control and Prevention 2019a; Rudd et al 2016a; Scholl et al 2018)
Random effects modeling based on pooled data revealed that legalizing marijuana for medical use was associated with a statistically non-significant 8% reduction in opioid overdose mortality (95% confidence interval: − 0.21 to 0.04; p = 0.201) and a 7% reduction in prescription opioids dispensed (95% confidence interval: − 0.13 to − 0.01; p = 0.017)
4 studies presented results regarding the impact of state Medical marijuana law (MML) on opioid overdose mortality (Bachhuber et al 2014; Phillips and Gazmararian 2017; Powell et al 2018; Smart 2016), 7 on opioid prescriptions dispensed (Bradford and Bradford 2017; Bradford and Bradford 2016; Bradford et al 2018; Liang et al 2018; Powell et al 2018; Stith et al 2018; Wen and Hockenberry 2018), 3 on nonmedical use or abuse of prescription opioids (Cerda et al 2018; Shi 2017; Wen et al 2015), and two on prescription-opioid related hospitalizations (Powell et al 2018; Shi 2017)

Summary

Introduction

Drug overdose is the leading cause of injury mortality in the United States (Ahmad et al 2018; Centers for Disease Control and Prevention 2019a; Rudd et al 2016a; Scholl et al 2018). The opioid epidemic has gone (2019) 6:38 and continues to present day, characterized by the steady increase in overdose deaths involving illicitly manufactured fentanyl and analogs (Centers for Disease Control and Prevention 2019b; Cicarrone 2017; Rudd et al 2016b; Seth et al 2017). In response to the continuing increase in overdose mortality, the US federal government declared the opioid epidemic a national public health emergency in October 2017. Between 1999 and 2017, prescription opioid overdose claimed about 218,000 lives in the United States (Centers for Disease Control and Prevention 2018b, 2019b; Scholl et al 2018). The purpose of this systematic review is to synthesize the empirical evidence regarding the impact of state marijuana laws on opioid overdose mortality and other opioid-related health outcomes

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