MEDLINE, AMED, British Nursing Index, CINAHL, EMBASE, PsycINFO, The Cochrane Library, Korean Medical Databases, Chinese Medical Databases and the Qigong and Energy Medicine Database were searched from inception to January 2007; search terms were reported. Reference lists of all located articles, relevant book chapters and departmental files were handsearched. Experts in the field were contacted for additional studies. No language restrictions were applied.