The authors analyzed several rigorously controlled studies that compared
the efficacy of ECT with that of simulated ECT, placebo, and
antidepressants. The data from these studies were combined statistically
(with the Mantel-Haenszel method for the combination of fourfold tables),
showing ECT's clear superiority over all these other forms of treatment for
severe depression. The authors similarly analyzed the data from several
studies comparing the efficacy of unilateral nondominant ECT with that of
bilateral ECT and found no significant difference in their efficacy.