Search strategy and data sources
To identify studies eligible for inclusion in this meta-analysis, we conducted a computerized search of clinical studies in PubMed (January 1966 to August 2019), EMBASE (January 1988 to August 2019), and Cochrane Library (database inception to August 2019). To minimize publication bias, references cited in the text of selected articles were further searched. Searches were performed using the keywords as Medical Subject Headings (National Library of Medicine, Bethesda, MD, USA), EMTREE, and natural language. Search terms used in this study were stated in the eAppendix in the Supplement.
This study was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions 8, 9 and the statement by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses group.10