Residual symptoms following electroconvulsive therapy: A retrospective cohort study

Background<bold>: </bold>Residual depressive symptoms following treatment are a burden for patients and are associated with increased risk of relapse. While this phenomenon has been explored following pharmacotherapy, there is little research into residual symptoms following electroconvulsive therapy (ECT). This study quantifies the frequency and type of residual symptoms following ECT treatment. Methods<bold>: </bold>This study used retrospective data from patients receiving ECT as part of routine clinical care. Depressive symptomatology was assessed using the Quick Inventory of Depressive Symptomatology - Self-Report 16 item scale (QIDS), which includes 9 symptom domains graded from 0 to 3. We quantified the frequency of mild or greater (QIDS >= 1) and moderate or greater (QIDS >= 2) residual symptoms following treatment among patients responding to ECT (QIDS decrease >= 50 % from baseline) and non-responders (QIDS decrease <50 %). Results<bold>: </bold>Among 1799 patients, 1015 (56.4 %) responded to ECT and 784 (43.6 %) did not. Among responders, 99.5 % had at least one residual symptom of mild severity or greater (median = 5, IQR = 3-6) and 83.3 % had at least one residual symptom of moderate severity or greater (median = 1, IQR = 1-2). Among non-responders, 100 % had residual symptoms of mild severity or greater (median = 8, IQR = 7-9), and 99.2 % had a residual symptom of moderate severity or greater (median = 4, IQR = 3-5). The most common residual symptoms among both responders and non-responders were sleep disturbances (93.1 % and 98.7 %, respectively) and sadness (68.9 % and 96.4 %, respectively). Limitations<bold>: </bold>Retrospective data from a single freestanding psychiatric hospital. Conclusion<bold>: </bold>Among patients with depression receiving ECT, there were high rates of residual symptoms even among patients responding to treatment.