Severity of substance use as an indicator of suicide risk among US military veterans

Background: Substance use is a strong risk factor for suicidal behavior. To date, however, no known study has evaluated optimal cut-off scores on substance use severity measures to identify individuals who may be at elevated risk for suicide. Methods: Data were analyzed from the 2019-2020 National Health and Resilience in Veterans Study, which surveyed a nationally representative sample of 4069 U.S. veterans. Receiver operating characteristic curve analyses were conducted to identify cut-off scores on the Alcohol Use Disorders Identification Test (AUDIT) and Screen of Drug Use (SDU) that optimally differentiated veterans with and without past-year suicidal ideation (SI) in the full sample, as well a high-risk subsample with histories of major depressive disorder (MDD) and/or posttraumatic stress disorder (PTSD). Results: The prevalence of past-year SI was 11.7% (n = 387); A total of 10.5% (n = 360) of the sample screened positive for past-year alcohol use disorder, 9.1% (n = 314) for past-year drug use disorder, and 22.4% (n = 833) for lifetime MDD/PTSD. The optimal AUDIT cut-off score that differentiated suicide ideators and non-ideators was >14 in the full sample, and >18 in the high-risk subsample; these scores are indicative of moderate-tosevere alcohol use disorder. The optimal SDU cut-off score was >1 for both the full sample and high-risk subsample, which is lower than the recommend cut-off score for probable drug use disorder (>7). Conclusions: Results identify high-specificity thresholds on the AUDIT and SDU that may have clinical utility in suicide risk assessment in veterans. Veterans with moderate-to-severe alcohol use disorder or who use nonprescription drugs may warrant further suicide risk assessment.