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

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.

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 × seizure threshold) or high-dose (6 × 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.

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).

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.