Titles and abstracts of papers were reviewed independently by 2
team members. Any citation marked for inclusion by either
team member went on to full-text screening, which was also
done independently by 2 researchers. Randomized controlled
trials were assessed using the Cochrane Collaboration’s tool for
risk-of-bias assessment14 (Appendix 2, available at www.cmaj
open.ca/content/2/4/E306/suppl/DC1).