3.1 Characteristics of included COSs
The first COS was published in 2000; the majority published year was 2018-2019 ( Fig.1). Forty-four COSs focus on 26 topics and mainly focused on pelvic organ prolapse (9%) and maternity care (9%) ( Fig.2). The included studies were conducted by the corresponding author from nine countries, mostly in the UK (38.6%), USA (13.6%), Canada (11.4%), and Australia (9%) ( Fig.3). The corresponding author of 40 COSs was from the developed country (91%) and four from the developing country (9%). The median journal impact factor (IQR) of OG COSs published was 5.079 (2.103, 5.357). And 13 COSs involved statistic or epidemiologic authors. There are 6 COSs developed with 1 to 3 authors, 15 COSs developed with 4 to 6 authors, 13 COSs developed with 7 to 10 authors, 10 COSs developed with more than ten authors, and twenty-five COSs were registered with protocol; twenty-four COSs declared funding sources; nine COSs proclaimed that they did not receive funds, and eleven COSs did not state whether they receive funds. Thirty-four COSs conducted a systematic review; twenty-nine COSs reported search strategy; only three COSs used the interview method. In addition, twenty COSs used the Delphi method, eleven of COSs conducted two rounds of Delphi, and nine of COSs conducted three rounds of Delphi, eighteen COSs used consensus meeting method, only sixteen COSs (36.4%) conducted both scoping process and consensus process. The main characteristics of the included COSs were presented in Table 1.