Table 2 Databases used for the search strategy
ASSIA 1987–June 2006ASSIA: Applied Social Sciences Index and Abstracts on the Web is an indexing and abstracting tool covering health, social services, economics, politics, race relations and education
CareData 1980–June 2006Social work and social care knowledge base
ChildData 1958–June 2006National Children’s Bureau database
CINAHL 1982–June 2006The Cumulative Index to Nursing and Allied Health (CINAHL) database provides authoritative coverage of the literature related to nursing and allied health
EMBASE 1980–June 2006The EMBASE family consists of three separate databases: (1) EMBASE: Excerpta Medica Database, and its subsets, (2) EMBASE Drugs and Pharmacology, and (3) EMBASE Psychiatry
MEDLINE 1950–June 2006Biomedicine, allied health, biological and physical sciences, humanities and information science as they relate to medicine and health care, communication disorders, population biology and reproductive biology
Ovid MEDLINE June 2006In-process and other non-indexed citations
SIGLE 1980–June 2006System for Information on Grey Literature in Europe is a bibliographic database covering European non-conventional (so-called grey) literature in the fields of pure and applied natural sciences and technology, economics, social sciences and humanities
TRIP Database 1997–June 2006The TRIP Database searches over 55 sites of high-quality medical information. It gives direct, hyperlinked access to the largest collection of “evidence-based” material on the web as well as articles from premier on-line journals
Sciences Citation Index 1981–June 2006Sciences Citation Index is a multidisciplinary database, covering the journal literature of the social sciences
ISI Proceedings 1990–June 2006Covers conference papers in all scientific and technical fields