Durability of antidepressant response to repetitive transcranial magnetic stimulation: Systematic review and meta-analysis

Background: The therapeutic options for treatment-resistant depression (TRD) encompass a range of neuromodulatory techniques, including repetitive transcranial magnetic stimulation (rTMS). While rTMS is safe and has documented short-term efficacy, durability of antidepressant effects is poorly established. Objective: Assess existing evidence regarding durability of rTMS-induced antidepressant response. Methods: We performed a systematic review of studies reporting antidepressant outcome measures collected three or more months after the end of an induction course of rTMS for depression. Among responders to the induction course, we used a meta-analytic approach to assess response rates at 3 (m3), 6 (m6) or 12 (m12) months after induction, and studied predictors of responder rates using meta-regression. Results: Nineteen studies published between 2002 and 2018 were included. Eighteen were eligible for analysis at m3 (732 patients) and m6 (695 patients) and 9 at m12 (247 patients). Among initial responders, 66.5% sustained response at m3 (95% CI = 57.1–74.8%, I² = 27.6%), 52.9% at m6 (95% CI = 40.3–65%, I² = 0%), and 46.3% at m12 (95% CI = 32.6–60.7%, I² = 0%), in the absence of any major bias. Random-effects meta-regressions further demonstrated that a higher proportion of women, as well as receipt of maintenance treatment, predicted higher responder rates at specific time-points. Conclusions: rTMS is a durable treatment for depression, with sustained responder rates of 50% up to 1 year after a successful induction course of treatment. Maintenance treatment may enhance the durability of the antidepressant effects of rTMS, and should be considered in clinical practice, as well as systematically explored in future clinical trials.