2.2 Identification and selection of COSs.
COMET has successfully brought together the international COS literature
in an online database
(http://www.comet-initiative.org/studies/search).8 We
conducted a comprehensive search of COMET database on December 20, 2019,
one reviewer (Y.G. or J.Y.S.) exported the entire registered COS study
records from the COMET database. The full-text publications that met our
inclusion criteria were then filtered. A regularly updated systematic
review of COSs was screened to identify OG COSs as a
supplement.8 The list of COSs was reviewed by a
COS/methodology expert (J.H.Z). No restriction was placed on language.