Severity of substance use as an indicator of suicide risk among U.S. military veterans

•The optimal AUDIT cut-off to identify suicidal ideation was ≥14 in the full sample.•For those with history of MDD/PTSD, the optimal AUDIT cut-off was ≥18.•The optimal SDU cut-off was ≥1 for both the full sample and MDD/PTSD subsample.•Veterans with moderate/severe AUD may need suicide risk assessment.•Veterans who use any non-prescription drug may warrant suicide risk assessment. 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. 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). 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-to-severe 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). 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 non-prescription drugs may warrant further suicide risk assessment.