Relapse following bitemporal and high-dose right unilateral electroconvulsive therapy for major depression

Objective Electroconvulsive therapy (ECT) is an effective acute treatment for severe and/or medication-resistant depression but maintaining remission following completion of a course remains a clinical challenge. Methods EFFECT-Dep Trial (ISRCTN23577151) participants with a DSM-IV major depressive episode who met remission criteria after a randomly assigned course of twice-weekly brief-pulse bitemporal (1.5 x seizure threshold) or high-dose (6 x seizure threshold) right unilateral ECT were monitored for relapse for 12 months. In line with the pragmatic trial design, all patients received treatment-as-usual individualised pharmacotherapy during and after ECT; no remitter received continuation ECT. Results Of 61 remitters, 24 (39.3%) relapsed, one (1.6%) withdrew from the study while in remission and the remaining 36 (59.0%) stayed well for a year. Most relapses occurred within the first six months, resulting in a cumulative six-month relapse rate of 31.1%. In a multivariable Cox proportional hazards regression model, older age (p = 0.039) and psychotic features at pre-ECT baseline (p = 0.037) were associated with a more favourable long-term prognosis while a greater number of previous depressive episodes (p = 0.028) and bipolar II (but not bipolar I) diagnosis (p = 0.030) were associated with a worse long-term outcome. Electrode placement and medication resistance prior to ECT had no effect on relapse. Adjusting for covariates, fewer patients treated with lithium relapsed in the overall group (p = 0.008) and in the unipolar depression subgroup (p = 0.027). Conclusion Long-term outcome following high-dose right unilateral ECT does not differ from bitemporal ECT. Prognosis is particularly favourable in older adults, psychotic depression and patients maintained on lithium.

Automated summary

The study suggests that older age, psychotic features, and treatment with lithium can improve long-term prognosis, while a history of multiple depressive episodes and a diagnosis of bipolar II disorder may lead to a worse long-term outcome. Electrode placement and medication resistance prior to ECT did not have an effect on relapse rates.