title: The authors reply.
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA; GlaxoSmithKline R&D, King of Prussia, PA; GlaxoSmithKline R&D, Stevenage, United Kingdom.
authors.forename: Jason
authors.initials: J
authors.lastname: Christie
authors.forename: Aili
authors.initials: A
authors.lastname: Lazaar
authors.forename: Andrew
authors.initials: A
authors.lastname: Bayliffe