Electroconvulsive therapy in the maintenance phase of psychotic unipolar depression

To determine whether the rates of readmissions and suicide vary in psychotic unipolar depression based on whether patients receive maintenance electroconvulsive therapy (M-ECT) following the initial series of ECT, and to examine if there is an age-dependent association.

We used Swedish national registries to identify hospitalized patients with psychotic unipolar depression, treated 2008-2019 who received ECT during their hospital stay. The patients who received subsequent M-ECT within 14 days after discharge were compared with those who did not. The primary composite outcome was time to readmission due to a psychiatric disorder, suicide attempt, or suicide within 2 years from discharge. Data were analyzed using Cox regression adjusted for previous psychiatric admissions, age, sex, comorbidity, and pharmacological treatment. We also conducted a within-individual analysis using the sign-test, with patients having ≥1 hospital episode followed by M-ECT and ≥1 hospital episode without M-ECT.

A total of 1873 patients were included, of which 130 received M-ECT. There was no statistically significant group difference regarding the primary outcome in the whole sample. However, when stratified by age, there was a significant difference in favor of M-ECT for patients >65 years (adjusted hazard ratio 0.55, 95% confidence interval 0.35-0.87). The within-individual analysis, including 46 patients, significantly favored M-ECT.

M-ECT was not associated with a differential risk of the composite of readmission and suicide in psychotic depression. Among patients >65 years, M-ECT was significantly associated with a decreased risk of the outcome. The possibility of residual confounding cannot be excluded.