To Örebro University

Importance: Electroconvulsive therapy (ECT) is indicated for severe depression, including depression with psychosis, catatonia, and/or an elevated suicide risk. However, the association of ECT with suicide risk is uncertain.

Objective: To determine the association between ECT and the risk of suicide in patients with unipolar major depressive disorder.

Design, Setting, and Participants: This registry-based cohort study used patient data from Swedish national registers. Patients with a record of inpatient care between January 1, 2012, and October 31, 2018, for moderate depression, severe depression, or severe depression with psychosis were included in the study. Propensity score matching (1:1) was used to balance risk factors for suicide at baseline between patients treated with and without ECT during the inpatient episode.

Exposures: Data from the Swedish National Quality Register for ECT and the Swedish National Inpatient Register were combined to identify patients who had received ECT during the inpatient episode. National registers were used to identify risk factors for suicide.

Main Outcomes and Measures: Suicide within 3 and 12 months of admission to inpatient care was analyzed. Cox regression analyses were used to adjust for confounders.

Results: The study included 28 557 patients (mean [SD] age, ECT group, 55.9 [18.4] years; non-ECT group, 45.2 [19.2] years; 15 856 women [55.5%]). In the matched sample of 5525 patients in each group, 62 patients (1.1%) in the ECT group and 90 patients (1.6%) in the non-ECT group died of suicide within 12 months (hazard ratio [HR], 0.72; 95% CI, 0.52-0.99). Electroconvulsive therapy was significantly associated with a decreased risk of suicide in patients with psychotic features (HR, 0.20; 95% CI, 0.08-0.54) and those aged 45 to 64 years (HR, 0.54; 95% CI, 0.30-0.99) or 65 years or older (HR, 0.30; 95% CI, 0.15-0.59), but not in patients aged 44 years or younger (HR, 1.22; 95% CI, 0.68-2.16).

Conclusions and Relevance: The results of this cohort study support the continued use of ECT to reduce suicide risk in hospitalized patients who are severely depressed, especially those who are older than 45 years and those with a psychotic subtype.