1. Research Institute of Primary Care and Health Sciences Keele University Staffordshire ST5 5BG U.K.
2. MRC Hub for Trials Methodology Research, School of Health and Population Sciences University of Birmingham Birmingham U.K.
3. Julius Center for Health Sciences and Primary Care University Medical Center Utrecht Utrecht The Netherlands
4. School of Health and Population Sciences University of Birmingham Birmingham U.K.
5. Department of Otolaryngology – Head & Neck Surgery, Boston Medical Center Boston University – School of Medicine Boston MA U.S.A.
6. School of Social and Community Medicine University of Bristol Bristol U.K.