International Journal of COPD (Oct 2022)
Functional Predictors Discriminating Asthma–COPD Overlap (ACO) from Chronic Obstructive Pulmonary Disease (COPD)
Abstract
Richard Kraemer,1,2,* Fabian Gardin,3,* Hans-Jürgen Smith,4 Florent Baty,5 Jürg Barandun,3 Andreas Piecyk,3 Stefan Minder,1 Jörg Salomon,1 Martin Frey,6 Martin H Brutsche,5 Heinrich Matthys7 1Centre of Pulmonary Medicine, Hirslanden Private Hospital Group, Salem-Hospital, Bern, Switzerland; 2Center for Translational Medicine and Biomedical Entrepreneurship, University of Bern, Bern, Switzerland; 3Centre of Pulmonary Medicine, Hirslanden Private Hospital Group, Clinic Hirslanden, Zürich, Switzerland; 4Medical Development, Research in Respiratory Diagnostics, Berlin, Germany; 5Department of Pneumology, Cantonal Hospital St, Gallen, Switzerland; 6Department of Pneumology, Barmelweid Hospital, Barmelweid, Switzerland; 7Department of Pneumology, University Hospital of Freiburg, Freiburg, Germany*These authors contributed equally to this workCorrespondence: Richard Kraemer, Center of Pulmonary Medicine, Hirslanden Private Hospital Group, Schänzlistrasse 39, Berne, CH-3013, Switzerland, Tel +41 79 300 26 53, Email [email protected]: A significant proportion of patients with obstructive lung disease have clinical and functional features of both asthma and chronic obstructive pulmonary disease (COPD), referred to as the asthma–COPD overlap (ACO). The distinction of these phenotypes, however, is not yet well-established due to the lack of defining clinical and/or functional criteria. The aim of our investigations was to assess the discriminating power of various lung function parameters on the assessment of ACO.Methods: From databases of 4 pulmonary centers, a total of 540 patients (231 males, 309 females), including 372 patients with asthma, 77 patients with ACO and 91 patients with COPD, were retrospectively collected, and gradients among combinations of explanatory variables of spirometric (FEV1, FEV1/FVC, FEF25-75), plethysmographic (sReff, sGeff, the aerodynamic work of breathing at rest; sWOB), static lung volumes, including trapped gases and measurements of the carbon monoxide transfer (DLCO, KCO) were explored using multiple factor analysis (MFA). The discriminating power of lung function parameters with respect to ACO was assessed using linear discriminant analysis (LDA).Results: LDA revealed that parameters of airway dynamics (sWOB, sReff, sGeff) combined with parameters of static lung volumes such as functional residual capacity (FRCpleth) and trapped gas at FRC (VTGFRC) are valuable and potentially important tools discriminating between asthma, ACO and COPD. Moreover, sWOB significantly contributes to the diagnosis of obstructive airway diseases, independent from the state of pulmonary hyperinflation, whilst the diffusion capacity for carbon monoxide (DLCO) significantly differentiates between the 3 diagnostic classes.Conclusion: The complexity of COPD with its components of interaction and their heterogeneity, especially in discrimination from ACO, may well be differentiated if patients are explored by a whole set of target parameters evaluating, interactionally, flow limitation, airway dynamics, pulmonary hyperinflation, small airways dysfunction and gas exchange disturbances assessing specific functional deficits.Keywords: COPD, COPD and coexisting asthma, ACO, aerodynamic work of breathing, airway dynamics, pulmonary hyperinflation, small airways dysfunction, precision medicine, multiple factor analysis, MFA, linear discriminant analysis, LDA
