Background: The aim of the current meta-analysis was to investigate predictors of the durability of the antidepressant effect of high-frequency (>1 Hz) repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex in the absence of active maintenance treatment.
Methods: Following a systematic literature search of Medline and PsycInfo, N = 16 double-blind, parallel-design, randomized-controlled trials (RCTs) with high-frequency rTMS and inactive sham were included in the current meta-analysis. The effect size (Cohen's d) was the standardized mean difference in depression scores between sham and rTMS groups (baseline -follow-up). Meta-analysis was conducted according to a random-effects model with inverse-variance weights.
Results: Most RCTs reported only short follow-up phases of 2 weeks (range of 1-16 weeks). The antidepressant effect was observed during follow-up (in the absence of maintenance treatment) compared to baseline (overall mean weighted d = -.48, 95% confidence interval: -.70, -.25, P < .001, N = 16 RCTs with 495 patients). Such an antidepressant effect during follow-up was higher in RCTs with patients who were less severely ill, unipolar, nonpsychotic, treatment-resistant, and on antidepressants (either started with rTMS or continued at stable doses during acute treatment phases). The effect sizes were lower in RCTs with longer (8-16 weeks) compared to shorter (1-4 weeks) follow-up periods. The risk of publication bias was low.
Conclusions: High-frequency rTMS has only a small antidepressant effect during follow-up after short acute treatment (5-15 sessions) in the absence of active maintenance treatment. This effect depends on illness severity, decreases over time, and appears to be enhanced by antidepressants.
Keywords: dorsolateral prefrontal cortex (DLPFC); long-term effect; major depressive disorder (MDD); randomized-controlled trial (RCT).
© 2015 Wiley Periodicals, Inc.