QUANTIFYING THE SPEED OF SYMPTOMATIC IMPROVEMENT WITH ELECTROCONVULSIVE-THERAPY - COMPARISON OF ALTERNATIVE STATISTICAL-METHODS

Although electroconvulsive therapy (ECT) is believed to have a rapid o nset of antidepressant activity, there has been limited investigation in this area. This study contrasted alternative statistical methods fo r testing treatment group differences in the rapidity of clinical resp onse to ECT. Patients with major depression were randomly assigned to receive right unilateral or bilateral ECT and Low or high electrical d osage relative to seizure threshold. The 24-item Hamilton Rating Scale for Depression (HRSD) was administered by blinded clinical raters twi ce weekly (nontreatment days). We evaluated four alternative statistic al strategies. Two methods considered time to improvement as a depende nt variable: (a) time (treatment number) to reach various cutoffs for percentage decrease in HRSD from baseline; and (b) survival analysis u sing the same cutoffs fur percentage decreases as endpoints. Two metho ds considered time to improvement as an independent variable: (c) the slope of linear regression of HRSD scores against treatment number; an d (d) a random regression model using the HRSD scores as repeated meas ures, The statistical methods differed in whether or not omnibus group differences were observed, the criterion level of improvement associa ted with group differences, and the results of pairwise comparisons es tablishing specific therapeutic advantages. Survival analysis generall y displayed the greatest sensitivity in detecting treatment group diff erences.