Individual response to electroconvulsive therapy is not correlated between multiple treatment courses.

OBJECTIVES

Electroconvulsive therapy (ECT) effectively treats depressive disorders, but many patients will have subsequent relapses. While some guidelines suggest prior response to ECT is an indication for ECT in a subsequent mood episode, it is unknown whether response to ECT is correlated between treatment courses. This study explores whether response to ECT at a first treatment correlates with response to treatment in a second independent ECT course.

METHODS

Single-center retrospective cohort of patients receiving two different ECT treatment courses between 2011 and 2020 and who self-reported depression symptoms using the Quick Inventory of Depressive Symptomatology (QIDS) at baseline and following treatment #5.

RESULTS

286 patients received two independent ECT series during the study period, of whom 153 received at least 5 treatments in both series. Patients had similar QIDS scores at the start of each treatment series (Pearson's correlation, r = 0.58, p <0.001), but the change in QIDS following 5 ECT treatments was not correlated between series for individual patients (Pearson's correlation, r = 0.083, p = 0.31). In multivariate analyses, change in QIDS was similar for both treatment series, but patients were less likely to receive 5 treatments in the second treatment series.

LIMITATIONS: retrospective cohort cannot control for factors influencing access to repeat ECT treatment

CONCLUSIONS

While on average final QIDS score was the same following two independent treatment courses, for individual patients the change in depression symptoms was not correlated between treatment series. Further research is needed to identify factors that may predict longitudinal ECT response.