Association Between Acute Alcohol Use and Firearm-Involved Suicide in the United States.

Importance: Firearms are the method of suicide used most often in the US. Acute alcohol use is associated with an increased risk of suicide by firearm. However, the dose-response association between acute alcohol use and the probability of using a firearm as the method of suicide is unknown. Objective: To evaluate the association between the amount of alcohol consumed and the probability of using a firearm as the method of suicide. Design, Setting, and Participants: This cross-sectional study used mortality data from the US National Violent Death Reporting System on suicide decedents aged 18 years or older with a positive blood alcohol concentration (BAC; ie, ≥0.01 g/dL). Statistical analysis was performed from January 2003 to December 2020. Exposure: Acute alcohol use, ascertained via postmortem toxicologic examination. Main Outcomes and Measures: Probability of using a firearm as the method of suicide compared with all other methods of suicide. Results: The study included 45 959 male suicide decedents (mean [SD] age, 42.6 [14.8] years) and 12 136 female suicide decedents (mean [SD] age, 44.2 [13.8] years) with a positive BAC; of those, 24 720 male decedents (53.8%) and 3599 female decedents (29.7%) used a firearm as the method of suicide. The probability of using a firearm as the method of suicide when alcohol is consumed was higher for male decedents, with the probability starting at just below 0.50 and increasing to approximately 0.75. In contrast, for female decedents, the probability began at just above 0.30 and increased to approximately 0.55. For both male and female decedents, the dose-response curves were an inverted U shape; as BAC increased, the probability of firearm-involved suicide initially increased and then decreased at very high BACs (approximately 0.40 g/dL for male decedents and approximately 0.30 g/dL for female decedents; these BACs were present among only a small percentage of alcohol-involved suicides: male decedents, 589 [1.3%]; female decedents, 754 [6.2%]). Conclusions and Relevance: This cross-sectional study of suicide decedents who had consumed alcohol prior to their death suggests that, as alcohol consumption increased, the probability of a firearm-involved suicide increased until a certain BAC, at which point the probability started to decrease.