Evaluation of State Cannabis Laws and Rates of Self-harm and Assault

Key Points Question Are state cannabis legalization laws with varying degrees of commercialization associated with rates of self-harm or assault injuries? Findings In this cohort study based on health insurance claims data from 75 395 344 beneficiaries between 2003 and 2017, rates of self-harm injuries among males younger than 40 years increased more in states legalizing recreational cannabis dispensaries compared with states without cannabis legalization laws. For other age and sex groups and for more restrictive legalization approaches, no association with self-harm and assault was found. Meaning States with recreational cannabis may benefit from monitoring levels of self-harm as a potential consequence of legalization.


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Self−harm Assault eFigure 9: Adjusted associations of medical and recreational cannabis commercialization with self-harm and assault injury rates, with additional adjustment for linear state-specific time trends, for the overall study population, [2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014][2015][2016][2017] Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with self-harm or assault injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals.    Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with self-harm or assault injuries, relative to state-months with medical cannabis without dispensaries. Bars represent the corresponding 95% confidence intervals. The primary analysis used all state-months 2003-2017, including statemonths with and without cannabis legalization laws. This analysis used only state-months in which some form of cannabis legalization was effective, with the most stringent category (medical, without dispensaries) as the reference category. Commercialization refers to the presence of dispensaries in either medical or recreational cannabis states. "Recreational with dispensaries" refers to the estimate for an interaction term between recreation (versus medical) legalization and commercialization. This analytic specification was not tested for analyses by age group and gender because such analyses effectively involve third-order interactions and were under powered.  Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with assault injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. The primary analysis used the number of insured beneficiaries in the given state and month as the denominator when calculating rates of self-harm and assault. In this sensitivity analysis, we used unique claims (the number of unique claims made per state-month) as the denominator, to account for changes in overall utilization over time.

Rate Ratio
eFigure 13: Adjusted associations of medical and recreational cannabis commercialization with self-harm injury rates, using unique claims as the denominator for outcome rates, by age group and gender, [2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014][2015][2016][2017] Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with self-harm injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. The primary analysis used the number of insured beneficiaries in the given state and month as the denominator when calculating rates of self-harm and assault. In this sensitivity analysis, we used unique claims (the number of unique claims made per state-month) as the denominator, to account for changes in overall utilization over time.

Policy level
Rate Ratio eFigure 14: Adjusted associations of medical and recreational cannabis commercialization with assault injury rates, using active members as the denominator for outcome rates, by age group and gender, [2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014][2015][2016][2017] Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with assault injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. The primary analysis used the number of insured beneficiaries in the given state and month as the denominator when calculating rates of self-harm and assault. In this sensitivity analysis, we used active members (the number of unique members who filed at least one claim per state month), because this approach is more robust to high-utilizing members.

Rate Ratio
eFigure 15: Adjusted associations of medical and recreational cannabis commercialization with self-harm injury rates, using active members as the denominator for outcome rates, by age group and gender, [2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014][2015][2016][2017] Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with self-harm injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. The primary analysis used the number of insured beneficiaries in the given state and month as the denominator when calculating rates of self-harm and assault. In this sensitivity analysis, we used active members (the number of unique members who filed at least one claim per state month), because this approach is more robust to high-utilizing members.

Policy level
Rate Ratio eFigure 16: Adjusted associations of medical and recreational cannabis commercialization with assault injury rates, adjusted for firearm availability, without the District of Columbia, by age group and gender, 2003-2017 Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with assault injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with self-harm injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with assault injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with assault injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. Legend: Points represent the estimated rate ratio for the association of each type of cannabis commercialization with self-harm injuries, relative to state-months not adopting any medical or recreational cannabis legalization over the same period. Bars represent the corresponding 95% confidence intervals. Legend: Points represent the estimated rate ratio for the association of naloxone overdose prevention laws (a negative control exposure) with assault injuries, relative to state-months not adopting such laws over the same period. The bars represent the corresponding 95% confidence intervals. Legend: Points represent the estimated rate ratio for the association of naloxone overdose prevention laws (a negative control exposure) with self-harm injuries, relative to state-months not adopting such laws over the same period. The bars represent the corresponding 95% confidence intervals.

Policy level
Rate Ratio