Text and Data Mining valid from 2015-04-16
Received: 4 November 2014
Revised: 6 January 2015
Accepted: 17 January 2015
First Online: 16 April 2015
: AS is the Joint Editor-in-Chief of, and HP is an Associate Editor of, npj Primary Care Respiratory Medicine; neither were involved in the editorial review of, nor the decision to publish, this article. The authors declare no conflict of interest.