Predictors of Remission After Electroconvulsive Therapy in Unipolar Major Depression

Context: Electroconvulsive therapy (ECT) is the most effective biological treatment for major depression. However, there is little agreement about clinically useful predictors of acute ECT outcomes.

Objective: To assess whether age, sex, burden of comorbid physical illness, age at onset, history of recurrence, episode duration, chronic depression or comorbid dysthymia, melancholic features, episode severity, and medication resistance are predictors of remission after an acute course of ECT.

Design: We performed an analysis using data gathered prospectively in 328 patients with unipolar major depression (according to Research Diagnostic Criteria) treated with ECT. The study was conducted from 1993 through 1999. Patients had a pretreatment score of 21 or higher on the 24-item Hamilton Rating Scale for Depression (HAM-D). Treatment history was assessed using the Antidepressant Treatment History Form. Remission was defined as a 24-item HAM-D score of 10 or less and a 60% or more relative reduction of the HAM-D score.

Results: On univariate logistic regression, statistically significant predictors of nonremission were chronic depression/dysthymia, medication resistance, longer episode duration, and younger age. On backward elimination logistic regression, only medication resistance (OR = 1.67, 95% CI = 1.05 to 2.67) and chronic depression/dysthymia (OR = 1.84, 95% CI = 1.06 to 3.21) were statistically significant predictors of nonremission.

Conclusions: In patients with major depression, lower rates of remission after acute ECT are associated with medication resistance and chronicity, but not with age or burden of physical illness.