Study selection and data extraction All studies were screened independently by two reviewers (Xiaotong Qiu and Xingwang Sun), based on the titles, abstracts, and full texts. Then, two reviewers independently extracted the following data in accordance to the Cochrane Handbook for Systematic Reviews of Interventions: first author, publication year, country, study design, demographic data of the patient population and so on. Ethics approval was not required for this analysis.
