RT Journal Article SR Electronic T1 Premature discontinuation of patients: a potential bias in COPD clinical trials JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society DO 10.1183/09031936.00104606 A1 S. Kesten A1 M. Plautz A1 C.A. Piquette A1 M.P. Habib A1 D.E. Niewoehner YR 2007 UL http://erj.ersjournals.com/content/early/2007/08/09/09031936.00104606.abstract AB