Gait speed and readmission following hospitalisation for acute exacerbations of COPD: a prospective study - Kon, SSC; Jones, SE; Schofield, SJ; Banya, W; Dickson, MJ; Canavan, JL; Nolan, CM; Haselden, BM; Polkey, MI; Cullinan, P; Man, WD-C (Thorax, 2015)