Predictors for the Efficacy of Electroconvulsive Therapy: Chart Review of a Naturalistic Study

Background: Several variables have been suggested that can predict the efficacy of electroconvulsive therapy (ECT) in patients suffering from depression. The results of studies into these predictors for ECT efficacy are not consistent.

Method: In a retrospective chart review of patients suffering from major depressive disorder and bipolar disorder according to DSM-IV criteria who have been given ECT in a psychiatric hospital in the Netherlands, predictors for ECT efficacy were explored. Information was gathered for predictors including sex, age, diagnosis, presence of psychosis, duration of index episode, medication treatment failure prior to ECT, medication during ECT course, and ECT variables. ECT was given twice weekly from November 1997 to June 2002. The 17-item Hamilton Rating Scale for Depression (HAM-D) was applied at baseline and weekly during the course.

Results: Seventy-three patients suffering from unipolar or bipolar depression were given ECT in the study period, with 56 patients (77%) meeting antidepressant treatment history form criteria for medication treatment failure. With remission defined as a reduction of depressive symptoms of at least 60% from baseline and a HAM-D end score of less than 8, 48 patients (65.8%) remitted. Forward stepwise logistic regression analysis selected only duration of index episode as a significant predictor for ECT efficacy. Medication treatment failure was not found to be a significant predictor. The concurrent use of psychotropic medication during ECT did not influence the efficacy.

Conclusion: Duration of index episode was the only variable found to significantly predict the efficacy of ECT.