Unilateral and bilateral repetitive transcranial magnetic stimulation for treatment-resistant depression: a meta-analysis of randomized controlled trials over 2 decades

Background: Approximately 35% of people with depression do not respond to 2 courses of antidepressant medications of adequate dosage, and treatment-resistant depression (TRD) is still a major clinical concern with a great impact on patients, their families, society and the health system. The present meta-analysis evaluates antidepressant efficacy of unilateral and bilateral repetitive transcranial magnetic stimulation (rTMS) in patients with unipolar TRD. Methods: We searched for randomized controlled trials that compared rTMS with sham treatment and were published by Apr. 3, 2017. The primary outcome was improvement in depression scores measured using the Hamilton Rating Scale for Depression. The secondary outcomes were remission and response rates. Two independent review authors screened the studies and extracted the data. Results: Twenty-three studies met the inclusion criteria. Meta-analysis of the depression scores showed a weighted mean difference (WMD) of 3.36 (95% confidence interval [CI] 1.85­4.88) between unilateral rTMS and sham treatment. Stratified data showed that the effect was relatively higher when rTMS was used as an add-on to antidepressant medications (WMD 3.64, 95% CI 1.52­5.76) than when it was used as a stand-alone treatment (WMD 2.47, 95% CI 0.90­4.05). The WMD between bilateral rTMS and sham was 2.67 (95% CI 0.83­4.51), and all studies that contributed to this outcome used rTMS while participants were taking antidepressant medications. The pooled remission and response rates for unilateral rTMS versus sham treatment were 16.0% and 25.1% for rTMS and 5.7% and 11.0% for sham treatment, respectively. The pooled remission and response rates for bilateral rTMS versus sham treatment were 16.6% and 25.4% for rTMS and 2.0% and 6.8% for sham treatment, respectively. Conclusion: This study suggests that rTMS has moderate antidepressant effects and appears to be promising in the short-term treatment of patients with unipolar TRD.