The minimal important difference for the St George's Respiratory Questionnaire in patients with severe COPD
Jorrit B.A. Welling, Jorine E. Hartman, Nick H.T. Ten Hacken, Karin Klooster, Dirk-Jan Slebos
European Respiratory Journal 2015 46: 1598-1604; DOI: 10.1183/13993003.00535-2015