sentences:  UnitedHealthcare noted that methodological concerns raised about the scientific evidence studying TMS for depression include small sample size, lack of a validated sham comparison in randomized controlled studies, and variable uses of outcome measures.Other commercial insurance plans whose 2013 medical coverage policies stated that the role of TMS in the treatment of depression and other disorders had not been clearly established or remained investigational included Aetna, Cigna and Regence.Policies for Medicare coverage vary among local jurisdictions within the Medicare system, and Medicare coverage for TMS has varied among jurisdictions and with time.