Quality assessment
The quality of the included RCTs was assessed with the Cochrane Risk of Bias Tool26. It contained six domains: randomization process, intervention deviation, missing outcome data, outcome measurement, selective outcome reporting. The retrospective studies were assessed by the Newcastle-Ottawa Scale (NOS) in the following 3 aspects: cohort selection, cohort comparability, assessment of outcome27. Details of NOS were available in Appendix 1.