[1] Ottawa Hosp, Res Inst, Clin Epidemiol Program, Ottawa, ON, Canada
[2] Univ Amsterdam, Univ Med Ctr, Amsterdam Univ Med Ctr, Dept Clin Epidemiol Biostat & Bioinformat, Amsterdam, Netherlands
[3] Univ Ottawa, Dept Radiol, Ottawa, ON, Canada
[4] McGill Univ, Jewish Gen Hosp, Lady Davis Inst, Montreal, PQ, Canada
[5] McGill Univ, Dept Psychiat, Montreal, PQ, Canada
[6] Univ Exeter, Coll Med & Hlth, Exeter Test Grp, Exeter, Devon, England
[7] Univ Sydney, Sydney, NSW, Australia
[8] Univ Birmingham, Inst Appl Hlth Res, Test Evaluat Res Grp, Birmingham, W Midlands, England
[9] Univ Hosp Birmingham NHS Fdn Trust, NIHR Birmingham Biomed Res Ctr, Birmingham, W Midlands, England
[10] Univ Birmingham, Birmingham, W Midlands, England
[11] Univ Amsterdam, Amsterdam Univ Med Ctr, Dept Resp Med, Amsterdam, Netherlands
[12] Univ Bristol, Bristol Med Sch, Populat Hlth Sci, Bristol, Avon, England
[13] Cochrane Netherlands, Univ Med Ctr Utrecht, Julius Ctr Hlth Sci & Primary Care, Utrecht, Netherlands
[14] Paris Descartes Univ, Necker Enfants Malades Hosp, AP HP, Ctr Res Epidemiol & Stat,Dept Paediat, Paris, France
[15] Paris Descartes Univ, Necker Enfants Malades Hosp, AP HP, Ctr Res Epidemiol & Stat,INSERM,UMR 1153, Paris, France
[16] Univ Bern, Berner Inst Hausarztmed, Inst Social & Prevent Med, Bern, Switzerland
[17] Univ Birmingham, Birmingham, W Midlands, England
[18] Brown Univ, Providence, RI 02912 USA
[19] McGill Univ, Dept Epidemiol Biostat & Occupat Hlth, Montreal, PQ, Canada
[20] Ottawa Hosp, Res Inst, Ctr Journalol, Clin Epidemiol Program, Ottawa, ON, Canada
[21] Univ Ottawa, Ottawa Hosp, Res Inst, Clin Epidemiol Programme, Ottawa, ON K1E 4M9, Canada