Ambrose, C S
Caspard, H
Rizzo, C
Stepka, E C
Keenan, G
Article History
Received: 25 November 2014
Revised: 25 November 2014
Accepted: 27 January 2015
First Online: 2 April 2015
Competing interests
: CSA, HC, CR and GK are employees of AstraZeneca and may have stock or stock options. ECS has no conflict of interest to declare.