Irritability as an independent predictor of concurrent and future suicidal ideation in adults with stimulant use disorder: Findings from the STRIDE study

Background: This report evaluated whether irritability in adults with stimulant use disorder is associated with suicidal ideation (SI) at the same visit (i.e., concurrently) and whether early changes in irritability predict subsequent levels of SI. Methods: Adults with stimulant use disorder (n=302) from nine residential addiction treatment programs were included. Participants were randomized to augmentation of usual care with dosed exercise or health education intervention. Irritability, SI, and depression were measured every week with 5-item irritability domain of Concise Associated Symptom Tracking scale, 3-item suicidal thoughts factor of Concise Health Risk Tracking scale, and 16-item Quick Inventory of Depressive Symptomatology Clinician-Rated version (excluding the suicide-related item) respectively during acute-(baseline-to-week-12) and continuation-(week-12-to-week-36) phase. Covariates included age, sex, race, ethnicity, treatment arm, type of substance(s) used, and comorbid psychiatric and medical disorders. Results: Higher irritability was associated with higher SI concurrently both in the acute-phase: r=0.28 (p<0.0001) and in the continuation-phase: r=0.33 (p<0.0001). Irritability was associated with concurrent SI after controlling for depression [acute-phase: β=0.17 (p<0.0001); continuation-phase: β=0.18 (p<0.0001)]. Greater baseline-to-week-2 reductions in irritability predicted lower levels of SI from week-2-to-week-12 (β=-0.11, p=0.003) and from week-12-to-week-36 (β=-0.22, p<0.0001) after controlling for baseline levels of depression and SI and baseline-to-week-2 changes in depression and SI. Limitations: Secondary analyses, self-report measures of irritability and SI, limited generalizability. Conclusions: Irritability is associated with SI concurrently, and greater reductions in irritability earlier in treatment are associated with lower levels of subsequent SI. Therefore, targeting irritability may reduce suicidality in adults with stimulant use disorder.