Bilateral repetitive magnetic stimulation (rTMS) is a promising novel therapeutic intervention for major depression (MD). However, clinical trials to date have reported conflicting evidence concerning its overall efficacy, which might have resulted from low statistical power. Thus, meta-analytical approaches could be useful in examining this issue by allowing the integration of findings from multiple studies and thus producing more accurate estimates of the treatment effect.

We searched the literature for randomized, double-blind and sham-controlled trials (RCTs) on bilateral rTMS for treating MD from 1995 to July 2012 using EMBASE, PsycINFO, Cochrane Central Register of Controlled Trials, SCOPUS, and ProQuest Dissertations and Theses, and from October 2008 until May 2012 using Medline. The main outcome measures were response and remission rates. We used a random-effects model, odds ratios (ORs) and the number needed to treat.

Data were obtained from seven RCTs, totaling 279 subjects with MD. After an average of 12.9 (s.d. = 2.7) sessions, 24.7% (40/162) and 6.8% (8/117) of subjects receiving active bilateral rTMS and sham rTMS were classified as responders [OR 4.3, 95% confidence interval (CI) 1.95–9.52, p < 0.0001]. Also, 19% (23/121) and 2.6% (2/77) of subjects were remitters following active bilateral rTMS and sham rTMS, respectively (OR 6.0, 95% CI 1.65–21.8, p = 0.006). No difference between baseline mean depression scores for the bilateral and sham rTMS groups was found, and the former was comparable with the latter in terms of drop-out rates at study end. Furthermore, we did not find significant differences efficacy- and acceptability-wise between active bilateral and unilateral rTMS at study end. Finally, heterogeneity between the included RCTs was not significant, and the risk of publication bias was found to be low.

Bilateral rTMS is a promising treatment for MD as it provides clinically meaningful benefits that are comparable with those of standard antidepressants and unilateral rTMS. Furthermore, bilateral rTMS seems to be an acceptable treatment for depressed subjects.