Summary of included systematic reviews.

*Outcome of operating time for caesarean sections was taken from review 25 (see text for details): $1: one observational study was mentioned in the paper but not described clearly; CABG: Coronary Artery Bypass Graft; RR reported relative risk (default is odds ratio); $2: includes 66 duplicate observations with review 25; $3 observational studies are not included for the outcome surgical site infection; $4∶15 studies meet the review inclusion criteria but only 1 was a staples v. sutures comparison; $5∶4 RCTs identified but one excluded later by the authors as not being a staples V. sutures comparison; $6∶1 observational study not included in results; Total obs.: is the total number of randomised observations over all trials which reported staples v. sutures (it excludes any non staples v. Sutures comparison, but includes both observational and randomised studies).