Review criteria
We searched MEDLINE, EMBASE, Epistemonikos and the Cochrane Central
Register of Controlled Trials from inception to April 2020. Pairs of
reviewers independently screened all identified records with titles,
abstracts and full texts using EndNote and Covidence software. We
reported the number of eligible studies according to design, sample
size, methodological quality / risk of bias, and proportions and
measures of association for primary outcomes for each low value
practice.