We will develop a search strategy for MEDLINE, accessed via PubMed, based on an analysis of the medical subject headings (Mesh) terms for all potential relevant publications and text words of key articles identified a priori. The search will be updated during the peer review process. We will search the following databases for primary studies: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Educational Resources Information Center (ERIC), PsycInfo, and Research and Development Resource Base in Continuing Medical Education (RDRB/CME). If possible, we will also search the EPOC register. Our preliminary search strategy for MEDLINE is shown in Appendix A.