Conflict of interest: M. Gaga reports grants and personal fees from AZ, grants from BI, Elpen, Novartis and Menarini, personal fees from BMS, MSD, Chiesi and Pharmaten, outside the submitted work. Conflict of interest: E. Zervas reports personal fees consultancy and lectures from Astra, Bristol-Myers Squibb, Chiesi, GSK, Elpen, Merck, MSD, Novartis, Menarini and Pfizer, non-financial support for travel, accommodation and meeting expenses from Astra, Bristol-Myers Squibb, Galenica, Chiesi, Elpen, Novartis, Menarini and Roche, outside the submitted work.