Does lithium prevent relapse following successful electroconvulsive therapy for major depression? A systematic review and meta-analysis

Objective The risk of relapse following successful antidepressant treatment, including electroconvulsive therapy (ECT), is substantial. Lithium has been suggested to effectively prevent relapse, yet data remain limited and inconclusive. We performed a systematic review and meta-analysis to examine the efficacy of continuation treatment with lithium in preventing relapse following a successful acute course of ECT in patients with major depression, in comparison to continuation treatment without lithium. We also assessed the role of several study characteristics, possibly impacting the treatment effect. Methods A systematic literature search, using the PubMed, Embase, Web of Science, and Cochrane Library databases (up to June 2020), was conducted for prospective and retrospective studies, including patients with unipolar or bipolar depression, that assessed the efficacy of lithium for post-ECT depressive relapse prevention. Results Of 2556 records screened, 14 articles reporting on 9748 participants who received continuation treatment either with (N = 1571) or without lithium (N = 8177) were included in the meta-analysis. Patients receiving lithium were less likely to experience depressive relapse after a successful acute course of ECT, compared to patients receiving post-ECT prophylaxis without lithium (weighted odds ratio (OR) = 0.53, 95% confidence interval (CI) = 0.34, 0.82), with a number needed to treat (NNT) of 7 (95% CI = 4, 21). We found some limited evidence that older patients may benefit more from continuation treatment with lithium, compared to younger patients. Using the GRADE criteria, the quality of evidence for our outcome measure (i.e., relapse rate) was rated as very low. Conclusion Continuation treatment with lithium may have superior efficacy in reducing the risk of relapse after a successful acute ECT course for major depression, in comparison to continuation treatment without lithium. High-quality studies are needed to confirm this finding.