Is baseline medication resistance associated with potential for relapse after successful remission of a depressive episode with ECT? Data from the Consortium for Research on Electroconvulsive Therapy (CORE).

Objective: To test whether pre-electroconvulsive therapy (ECT) medication resistance is associated with post-ECT relapse rates.

Method: In a post hoc analysis of data from a large multicenter trial of post-ECT relapse prevention strategies (conducted from May 1997 to July 2004), we assessed whether response to antidepressant medications prior to ECT for a unipolar nonpsychotic depressive episode (DSM-IV) was associated with differential relapse rates after remission with ECT. Baseline (i.e., pre-ECT) medication use was assessed with the Antidepressant Treatment History Form. Following remission with ECT that was stable for 1 week, patients were randomly assigned to receive 6 months of treatment with either combination lithium carbonate/nortriptyline or continuation ECT. Relapse was assessed with the 24-item Hamilton Rating Scale for Depression. There were 146 patients followed in the first week after remission (termed the interim week in this study), and 73 in the randomized phase of the study. For the purposes of this trial, medication resistance is defined as not having responded to at least 1 adequate trial of an antidepressant medication before ECT.

Results: In the first week after acute remission, 9.8% of patients not having at least 1 antidepressant medication trial met relapse criteria, while 31.4% of medication-resistant patients met relapse criteria, a difference that was statistically significant (p = .026). In the randomized phase of the study, 34.6% of non-medication-resistant patients relapsed, while 50.0% of medication-resistant patients relapsed, a difference that was not significant (p = .434).

Conclusion: We conclude that nonpsychotic patients who had at least 1 adequate antidepressant medication trial before ECT may be especially prone to early relapse after successful acute remission with ECT.