7Guyatt GH, Oxman AD, Vist GE, et al. GRADE: an emer- ging consensus on rating quality of evidence and strength of reeommendation[J]. BMJ, 2008,336 (7650) : 924-926.
8The Joanna Briggs Institute Levels of Evidence and Grades of Recommendation Working Party. Supporting Document for the Joanna Briggs Institute levels of Evidence and Grades of Recommendation[J]. The Joanna Briggs Institute. 2014. ht- tp://joannabriggs, org/ibi-approach, html tabbed-nay Lev- els-of-Evidence.
9Balshem H, Hell M, Schunemann, HJ,et al. GRADE guidelines: 3. Rating the quality of evidence[J]. J of Clinical Epidemiology, 2011,64(4) :401-406.