Prevalence and predictors of substance use as a factor in suicide in the USA, 2015-2020: a repeated cross-sectional analysis.

Abstract

Background: US rates of substance abuse and suicide mortality increased dramatically in recent years, but little is known about how rising rates of drug and alcohol use are associated with suicide. This study explores the role of substance use in suicide between 2015 and 2020 and identifies individual and geographical factors associated with these patterns.

Methods: Repeated cross-sectional data on 103 817 suicide decedents drawn from the 2015-2020 National Violent Death Reporting System, combined with Census geographical data, are examined. Available toxicology reports are investigated to identify shifts in substances involved in suicide. A mixed effects logistic model is applied to identify factors associated with the probability of substance use as a precipitating circumstance for suicide.

Results: Close to one in five suicide decedents had a substance-related circumstance. Relative to 2015, the probability of drug or alcohol problems surrounding suicide is higher in subsequent years (eg, in 2020, the probability is 2.6% and 2.5% higher, respectively). The detection of alcohol, the substance most identified in toxicology reports, remained stable over the period. Positive tests for prescription opioids and benzodiazepines declined while those for illicit opioids, marijuana and amphetamines increased. The probability of a drug abuse suicide circumstance is higher among white (Average Marginal Effect (AME) =0.038) and male (AME=0.006) decedents, and lower among those with a college degree (AME=-0.099) and who are foreign-born (AME=-0.078). For alcohol-related suicide circumstances, the corresponding AMEs are 0.033 (white), 0.055 (male), -0.045 (college degree) and -0.035 (foreign-born). After adjusting for individual characteristics, county median household income is associated with a reduced probability of drug abuse circumstances but a higher probability of alcohol problems. Unmet need for treatment at the state level is associated with a higher probability of alcohol-related suicide (AME=0.022).

Conclusions: Findings suggest shifts in the substances linked to suicide and reveal the importance of a place's social structure in shaping the substance use-suicide nexus.