Correction to: npj Primary Care Respiratory Medicine (2014) 24, 14072; doi:10.1038/npjpcrm.2014.72; published online 25 September 2014

Since the online publication of the above article, it has been noted that the names of the second and fifth authors were published incorrectly. The correct names are given above. The corrected article appears online together with this corrigendum.

The authors would like to apologise for this error.