This review has been withdrawn following Feedback from Andrei V. Krassioukov, Kathleen Christison, Matthias Walter, Jean‐Jacques J.M. Wyndaele, Thomas M. Kessler and Michael Kennelly who have identified possible errors in the analysis of data in the review. These concern handling of cross‐over and multi‐arm trials as well as corrections and clarifications of data used. This review has been withdrawn whilst these issues are addressed. Changes are also required to reflect current methodological standards. The review will be re‐published following updating, revision and peer review.