Early suicidal ideation change and suicidality-associated emergency department utilization after ketamine or esketamine treatment in treatment-resistant depression

Background: Ketamine and esketamine ((es)ketamine) rapidly reduce depressive symptoms and suicidal ideation (SI) in treatment-resistant depression (TRD), but whether early SI improvement during the acute phase of the treatment predicts reduced suicide-associated emergency department (SAED) visits over the longer term remains unclear. Objectives: To examine whether early improvements in SI, measured using item 12 of the Quick Inventory of Depressive Symptomatology – Self Reported (QIDS-SR), following (es)ketamine treatment are associated with SAED visits over 6 months Design: Retrospective cohort study. Methods: Individuals with TRD who had available data on SI measured using the QIDS-SR during the acute phase, as well as data on SAED visits over 6 months, were included. Participants were classified based on changes in SI as resolved, partially improved, or unchanged/worsened using the QIDS-SR item 12 during acute treatment (up to six intravenous (IV) or eight intranasal (IN) treatments) and were followed for SAED visits. Results: Among 96 patients with SI data, 73 (76%) had baseline SI. Following acute-phase treatment, 36 (49%) achieved SI resolution, 14 (19%) partially improved, and 23 (32%) were unchanged/worsened. During the 6-month follow-up, 8 (11%) had post-acute SAED visits. While not statistically significant, patients with resolved SI had lower odds of post-acute ED visits (OR = 0.16, p = 0.12). Kaplan–Meier estimates of SAED visit-free survival across three SI change groups trended toward significance ( p = 0.066), suggesting lower cumulative healthcare (ED) utilization in more favorable change groups. Secondary analysis among 57 patients who received IV ketamine and had baseline SI showed that, after two infusions, 33 (47.2%) demonstrated a reduction in SI. Early SI improvement (⩾50% reduction in SI) was associated with a lower likelihood of any post-treatment SAED visit at 6 months after adjusting for pre-treatment SAED (OR = 0.17, 95% CI: 0.02–0.98, p = 0.047), corresponding to numbers needed to treat of 4.3. Conclusion: Early SI changes may have prognostic implications, though larger studies are needed to confirm clinical significance.