Chavannes, Niels H
Du Puy, Robert S
Bai, Chunxue
Article History
Received: 19 November 2014
Revised: 26 May 2015
Accepted: 31 May 2015
First Online: 9 July 2015
Competing interests
: NHC is an Associate Editor of <i>npj Primary Care Respiratory Medicine</i>, but was not involved in the commissioning or processing of this manuscript or the decision to publish it. The other authors declare no conflict of interest. All authors have contributed to writing and revision of the manuscript.