[1] Univ Med Ctr Utrecht, Dept Rehabil Nursing Sci & Sports, HP W01-121,Heidelberglaan 100, NL-3508 GA Utrecht, Netherlands
[2] Univ Med Ctr Utrecht, Julius Ctr Hlth Sci & Primary Care, Utrecht, Netherlands
[3] Radboud Univ Nijmegen, Med Ctr, Dept Primary & Community Care, Nijmegen, Netherlands
[4] McGill Univ, Ctr Hlth, Dept Med, Resp Epidemiol & Clin Res Unit, Montreal, PQ, Canada
[5] Glasgow Royal Infirm, Dept Resp Med, Glasgow G4 0SF, Lanark, Scotland
[6] Vet Adm Portland Hlth Care Syst, Portland, OR USA
[7] Oregon Hlth & Sci Univ, Portland, OR 97201 USA
[8] Repatriat Gen Hosp, Dept Resp Med, Adelaide, SA, Australia
[9] Christchurch Hosp, Canterbury Dist Hlth Board, Resp Serv, Christchurch, New Zealand
[10] Sorlandet Hosp, Dept Pulm Med, Kristiansand, Norway
[11] Ctr Res Environm Epidemiol CREAL, Barcelona, Spain
[12] Univ Pompeu Fabra, Barcelona, Spain
[13] CIBERESP, Barcelona, Spain
[14] Univ Glasgow, Robertson Ctr Biostat, Glasgow, Lanark, Scotland
[15] Univ Med Ctr Utrecht, Julius Ctr Hlth Sci & Primary Care, Utrecht, Netherlands
[16] Kaiser Permanente Southern Calif, Dept Res & Evaluat, Pasadena, CA 91101 USA
[17] Univ Twente, Dept Res Methodol Measurement & Data Anal, POB 217, NL-7500 AE Enschede, Netherlands
[18] Med Spectrum Twente, Dept Clin Epidemiol, Enschede, Netherlands
[19] Minneapolis Vet Affairs Hlth Care Serv, Div Pulm Allergy Crit Care & Sleep Med, Minneapolis, MN USA
[20] Univ Minnesota, Minneapolis, MN USA
[21] Queen Mary Univ London, Ctr Primary Care & Publ Hlth, London, England
[22] Catholic Univ Louvain, Dept Rehabil Sci, Leuven, Belgium
[23] UNSW Australia, Sch Publ Hlth & Community Med, Sydney, NSW, Australia