FOOTPRINTS study protocol: rationale and methodology of a 3-year longitudinal observational study to phenotype patients with COPD.
Crapo J, Gupta A, Lynch DA, Vogel-Claussen J, Watz H, Turner AM, Mroz RM, Janssens W, Ludwig-Sengpiel A, Beck M, Langellier B, Ittrich C, Risse F, Diefenbach C. FOOTPRINTS study protocol: rationale and methodology of a 3-year longitudinal observational study to phenotype patients with COPD. BMJ Open. 2021 03 22; 11(3):e042526.