1. Faculty of Medicine, University of Malaya; Department of Primary Care Medicine; Kuala Lumpur Malaysia 50603
2. University of Nottingham; Division of Primary Care, School of Medicine; 1307 The Tower University Park Campus Nottingham UK NG9 2RD
3. Kleijnen Systematic Reviews Ltd; Unit 6, Escrick Business Park Riccall Road, Escrick York UK YO19 6FD
4. School for Public Health and Primary Care (CAPHRI), Maastricht University; Maastricht Netherlands 6200 MD