2.4 Study selection and data quality assessment
We employed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA ) guidelines in our analysis [15,16]. First, the titles and abstracts of the articles were screened. Second, we collected all relevant articles for full-text assessment. In addition, we scrutinized the references of the included articles and some reviews to search for more relevant articles. Two authors independently performed the search and reviewed all publications found relevant to this study. We resolved any disagreements about inclusion or analysis by consensus or mediation by a third reviewer.