Systematic review of preservation TMS that includes continuation, maintenance, relapse-prevention, and rescue TMS

Background: A dearth of evidence-based information exists to guide the delivery of transcranial magnetic stimulation (TMS) after a successful acute course of treatment for Major Depressive Disorder. Methods: To provide guidance for clinicians, existing literature focused on “preservation TMS” was systematically reviewed and synthesized. Preservation TMS was defined as TMS used to sustain a clinical response after a successful acute course of treatment and included reports using the terms maintenance, continuation, relapse prevention, or rescue TMS. The review protocol was registered on Open Science Framework and reported following PRISMA guidelines. Data were abstracted by two authors and discrepancies were resolved by a third author. Primary outcome measures focused on clinical efficacy. The evaluated studies were graded using the Levels of Evidence criteria published by the Oxford Centre for Evidence-Based Medicine. Results: The search included 536 abstracts and 16 additional papers, from which 63 full articles were screened. Data were abstracted from 30 qualifying sources (N=1,494) including 4 randomized controlled trials (one sham controlled), 14 open trials, and 12 case series. Overall, the quality of existing literature was low regarding efficacy but provided clear support for effectiveness and safety across a range of preservation TMS protocols based on mostly uncontrolled studies. Conclusions: Existing literature suggests that preservation TMS protocols significantly vary and are mostly supported by open trials and case series. Due to a lack of effective alternatives, preservation TMS will likely be required for certain patients who respond to acute TMS therapy. More studies of preservation TMS are critically needed.