MEDLINE using Pubmeda; EMBASEb; Cochrane Database of Systematic Reviews
aEach of the terms were crossed (Boolean AND) with the Medline strategy described by Haynes et al.  for detecting RCTs. In addition, each was also crossed with the MeSH term 'clinical trials as topic'.
bEach of the terms were crossed (Boolean AND) with the EMBASE strategy described by Wong et al.  for detecting RCTs.