Systematic reviews show that repetitive transcranial magnetic stimulation (rTMS) is superior to sham control conditions in patients with major depressive disorder, but the clinical relevance is not clear. None have specifically examined outcomes in patients with treatment-resistant depression (TRD).

A systematic review was conducted by identifying published randomized controlled trials of active rTMS, compared with a sham control condition in patients with defined TRD (that is, at least one failed trial). The primary outcome was clinical response as determined from global ratings, or 50% or greater improvement on a rating scale. Other outcomes included remission and standardized mean differences in end point scores. Metaanalysis was conducted for absolute risk differences using random effects models. Sensitivity and subgroup analyses were also conducted to explore heterogeneity and robustness of results.

A total of 24 studies (n = 1092 patients) met criteria for quantitative synthesis. Active rTMS was significantly superior to sham conditions in producing clinical response, with a risk difference of 17% and a number-needed-to-treat of 6. The pooled response and remission rates were 25% and 17%, and 9% and 6% for active rTMS and sham conditions, respectively. Sensitivity and subgroup analyses did not significantly affect these results. Dropouts and withdrawals owing to adverse events were very low.

For patients with TRD, rTMS appears to provide significant benefits in short-term treatment studies. However, the relatively low response and remission rates, the short durations of treatment, and the relative lack of systematic follow-up studies suggest that further studies are needed before rTMS can be considered as a first-line monotherapy treatment for TRD.