Search methods for identification of studies
We searched electronic bibliographic databases: The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2005, issue1), which include the Specialized Register Search; MEDLINE (OVID - January 1966 to February 2005); EMBASE ((OVID -January 1988 to February 2005); and CINAHL ((OVID -January 1967 to February 2005) with no language or time restrictions. Search strategies were developed for each database to take account of differences in controlled vocabulary and syntax rules. See Appendix 1; Appendix 2; Appendix 3; Appendix 4