Suboptimal Peak Inspiratory Flow, COPD Exacerbations, Hospitalisations, and Disease Burden: A Longitudinal Follow-Up in a Multicentre Real-World Study

Background Peak Inspiratory Flow (PIF) is a critical determinant of dry powder inhaler (DPI) effectiveness in managing patients with Chronic Obstructive Pulmonary Disease (COPD). Suboptimal PIF may compromise drug delivery and clinical outcomes. Objective To evaluate the association between repeated PIF measures and disease exacerbations, hospitalisations, and symptom burden in patients with stable COPD. Methods In this multi-country, observational cohort, 415 participants aged ≥40 years with confirmed COPD and a smoking history underwent PIF measurements at their prescribed inhaler's resistance, and low-, and high-resistance levels using the In-Check DIAL G16. Clinical assessments occurred at 3 months (Follow-Up 1, FU1) and 6 months (Follow-Up 2, FU2) including spirometry, COPD Assessment Test (CAT) scores, medication use, and exacerbation/hospitalisation rates. Results At FU1, 29.4% (n=113/384) had typical suboptimal PIF and 28.6% (n=108/377) remained suboptimal at FU2. Participants with suboptimal PIF were more often female and current smokers, with consistently poorer lung function across both visits: lower FEV1 (% predicted: 33.7±9.1% versus 45.7±9.2%, p=0.01), actual FVC and inspiratory capacity were observed. Suboptimal PIF significantly predicted moderate (p=0.03) and severe (p=0.01) exacerbations, was associated with higher hospitalisation risks (p=0.05), and with greater use of short-acting beta agonist, oral corticosteroid, and triple therapy. Conclusions Suboptimal PIF is a stable, clinically meaningful marker of worse COPD outcomes and may guide more personalised inhaler selection.