[Determinants of relapse after electroconvulsive therapy in depressed patients]

Maintaining remission after successful acute treatment remains a challenge in the use of electroconvulsive therapy (ECT). For this purpose, the concept of gradually tapered continuation ECT (C-ECT) has been increasingly propagated. The present study is aimed at identifying factors that contribute to relapse after ECT in depressed patients.

After successful acute treatment of a depressive episode with ECT, all patients were offered a fixed schedule of C-ECT. The number of C-ECT sessions varied in this naturalistic setting depending on compliance. All patients with follow-up data of at least 6 months were included (n = 82). Survival analyses with time to relapse as dependent variable were used to estimate the risk of relapse.

34.1 % of the patients relapsed within 6 months. Factors associated with a decreased relapse rate were: 1. C-ECT treatment, especially within the first three month; 2. higher mean charge during I-ECT; 3. switch from unilateral to bilateral electrode placement during I-ECT, and 4. male sex. However, the sensitivity analyses suggest that the influence of sex on relapse was limited to the first three months of the continuation phase.

As expected, C-ECT reduced relapse rates, especially when performed early after I-ECT. Besides, increased charge and a change of electrode placement from unilateral to bilateral during the index series were associated with a lower risk of relapse. Compared to men, there was a higher rate of relapse in women.