“…The characteristics of the included studies are shown in Tables 1 and S4. Eight studies were full‐text articles, 5,22,25,26,29,30,32,33 and six were conference abstracts 21,23,24,27,28,31 . Three studies were multicentre randomised controlled trials, 5,24,31 and the remaining 11 were retrospective cohort studies (six multicentres and five single centres) 21‐23,25‐30,32,33 .…”