RT Journal Article SR Electronic T1 Opioids in COPD: a cause of death or a marker of illness severity? JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1521 OP 1522 DO 10.1183/13993003.01573-2016 VO 48 IS 5 A1 Nicholas T. Vozoris A1 Denis E. O'Donnell A1 Chaim M. Bell A1 Sudeep S. Gill A1 Paula A. Rochon YR 2016 UL http://erj.ersjournals.com/content/48/5/1521.abstract AB