IMPORTANCE: While acute alcohol use (AAU) is known to increase the risk of suicide significantly, the underlying mechanisms of this association are still understudied. OBJECTIVE: To examine the association between AAU and the risk factors for suicide, focusing on the association between AAU and choice of suicide methods. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study included data from the Korean National Investigations of Suicide Victims Study (KNIGHTS). The KNIGHTS dataset comprises nationally representative data encompassing nearly all suicide deaths in South Korea from January 1, 2013, to December 31, 2020. The study was analyzed from November 2 to 10, 2023. MAIN OUTCOMES AND MEASURES: The main outcome was whether decedents who died by suicide had consumed alcohol before their death. Trained investigators conducted psychological autopsies by reviewing police reports of suicide deaths. Whether the decedent who died by suicide had consumed alcohol before death was determined from 3 sources: (1) confirmation by informants, (2) autopsy reports indicating a positive blood alcohol concentration, and (3) observations from police officers. Demographic characteristics, premortem psychiatric symptoms, and suicide characteristics, including method of suicide and presumed reasons for suicide, were examined. Hierarchical logistic regression models were used to examine the association between the contributing factors and AAU. RESULTS: This study included 55 226 decedents who died by suicide (65.5% male), of whom 21 998 (39.8%) were under the influence of alcohol at the time of death. AAU was associated with being male (odds ratio [OR], 1.37 [95% CI, 1.31-1.44])
being middle aged (eg, from age 30 to 39 years: OR, 1.20 [95% CI, 1.06-1.35])
and having alcohol use disorder symptoms (OR, 13.28 [95% CI, 12.38-14.24]). Among suicide methods, gas, drug, and pesticide poisoning showed a positive association with AAU, with gas poisoning showing the highest OR (OR, 1.88 [95% CI, 1.61-2.20]). An interaction was found between age and suicide method, with older adults (eg, aged 80 years or older) having higher odds of AAU when using methods such as drug (OR, 6.28 [95% CI, 3.53-11.17]), pesticide (OR, 6.56 [95% CI, 3.86-11.13]), and gas (OR, 2.48 [95% CI, 1.52-4.04]) poisoning. CONCLUSIONS AND RELEVANCE: The findings of this cross-sectional study suggest that AAU was associated with gas poisoning, as indicated by the ORs. Given that charcoal burning involves substantial preparation time, alcohol may have been deliberately used to facilitate planned suicide attempts. Furthermore, the deaths of older adults who consumed alcohol prior to suicide, even when using less lethal methods, highlight the critical need for monitoring and effectively managing alcohol use within this population.