1 Scientific Resource Center for the AHRQ EPC Program, Portland VA Research Foundation, Portland, OR, USA. Electronic address: Robin.Paynter@VA.gov.
2 Cochrane Collaboration, St Albans House, 57-59 Haymarket, London SW1Y 4QX, United Kingdom.
3 Scientific Resource Center for the AHRQ EPC Program, Portland VA Research Foundation, Portland, OR, USA.
4 RTI-UNC Evidence-based Practice Center Program, Cecil G. Sheps Center for Health Services Research, UNC-Chapel Hill, Campus Box 7590, 725 M.L.K. Jr Blvd, Chapel Hill, NC 27516, USA.
5 Brown Evidence-based Practice Center Program, Brown University School of Public Health, Box G-S121-8, Providence, RI 02912, USA.