Relevant trials were identified by electronic searches of MEDLINE (1966-April 2007), EMBASE (1974-2000), CINAHL (1982-April 2007), Psycinfo (1806-April 2007), Ovid OLDMEDLINE (1950-1965), ISI Web of Knowledge (1981-April 2007), National Library for Health (NLH) (April 2007), Nursing, Midwifery and Allied Health (NMAP) (April 2007), Intute: Medicine (December 2005), Proquest Nursing Journals (PNJ, 1986 - April 2007); rehabilitation databases: AMED (1985-April 2007), MANTIS (1880-2000), REHABDATA (1956-2000), REHADAT (2000), GEROLIT (1979-2000); English language databases of foreign language research and third world publications: Pascal (1984-2000), LILACS (1982- April 2007), MedCarib (17th Century-April 2007), JICST-EPlus (1985-2000), AIM (1993-April 2007), IMEMR (1984-April 2007), grey literature databases: SIGLE (1980-2000), ISI-ISTP (1982-April 2007), DISSABS (1999-2000), Conference Papers Index (CPI, 1982-2000) and Aslib Index to Theses (AIT, 1716- April 2006), The Cochrane Controlled Trials Register (Issue 2, 2007), the CenterWatch Clinical Trials listing service (April 2007), the metaRegister of Controlled Trials (mRCT, April 2007), Current controlled trials (CCT) (April 2007), ClinicalTrials.gov (April 2007), CRISP (1972-April 2007), PEDro (April 2007), NIDRR (April 2007) and NRR (April 2007) and the reference lists of identified studies and other reviews were examined.