Spirometry Coving Index: a novel predictor of asthma and COPD disease progression

<bold>Introduction:</bold> We assessed the impact of using a baseline assessment of Coving Index (CovI; a novel spirometry index representing the curvature of the expiratory flow volume loop, where higher values mean worse status) to predict trajectories in Pulmonary Health Index (PHI) score (a novel composite marker comprising percent predicted postbronchodilator FEV₁ [ppFEV₁], 12-month average Chronic Airways Assessment Test score and treatment intensity [based on GINA/GOLD reports]) over 3 years in patients with asthma or COPD. <bold>Methods:</bold> Baseline postbronchodilator spirometry data were analysed from patients with physician-assigned asthma or COPD (NOVELTY study). We calculated CovI (assessed by the ArtiQ. QC AI algorithm, Clario, BE) from the best manoeuvre (greatest sum of FEV₁ and FVC). We used unbiased latent class mixture models to identify PHI trajectories and assessed, from baseline characteristics, an impact of stratifying by CovI. <bold>Results:</bold> Overall, 5763 spirometry manoeuvres were included from 2167 patients: 1225 with asthma, 942 with COPD; mean (SD) age 59 (15) years; mean ppFEV₁ 77%. We identified 4 PHI trajectories (% of patients): stable-high (70.4), stable-low (20.5), decliners (6.2) and improvers (2.9). Stratifying the population based on baseline PHI and CovI increased the proportion of decliners from 4.3% to 5.7% in asthma and 8.7% to 18.7% in COPD. <bold>Conclusion:</bold> Including CovI in the baseline assessment of patients with asthma or COPD increased identification of patients (particularly in COPD) with declining pulmonary health based on PHI. Further analyses will assess if short-term change in CovI can predict long-term change in health status in patients with airways disease.