Flowchart. Three databases (Excerpta Medica Database [EMBASE], Medical Literature Analysis and Retrieval System Online [MEDLINE], and the Cochrane Central Register for Controlled Trials [CENTRAL]) were searched in addition to a manual search for eligible articles. Titles and abstracts of 5,073 articles were screened and 1,076 full texts assessed for eligibility. Finally, the data of 68 articles were included in qualitative and quantitative data synthesis.