*2.1. Data Sources and Search Strategy*

To find relevant studies, a total of nine electronic databases, including Medline via PubMed, Excerpta Medica dataBASE (EMBASE) via Elsevier, the Cochrane Central Register of Controlled Trials, Allied and Complementary Medicine, Korean Studies Information Service System, Korea Citation Index, China National Knowledge Database, Wanfang Database, and Chinese Scientific Journals Database (CSJD-VIP), were comprehensively searched by one researcher (BL), without any limitations on language and publication status. The search date was 12 February 2021, and all published studies up to the search date were considered. In addition, we reviewed the reference list of included or related

literature to find gray literature and requested advice from systematic review experts (Supplement S1).
