Association of PiSlope with lung function decline in individuals with preserved spirometry: a prospective cohort study

Background Airway remodeling precedes airflow obstruction in chronic obstructive pulmonary disease. Pi 10 assumes a consistent fixed slope between airway wall thickness and lumen perimeter across individuals. PiSlope comprehensively quantifies airway wall thickening, which is associated with increased acute exacerbation and mortality risk. Whether PiSlope is associated with respiratory prognosis in participants with preserved spirometry is unknown. Methods Participants with preserved spirometry with complete baseline questionnaires, spirometry, and chest computed tomography were enrolled from a 3–year prospective ECOPD cohort study and divided into four groups by PiSlope quartile (Q) (Q1: PiSlope≥0.4946, Q2: 0.4550≤PiSlope<0.4946, Q3: 0.4149≤PiSlope<0.4550, Q4: PiSlope<0.4149). Clinical outcomes included lung function decline and risk of airflow obstruction progression. Results 1140 participants with preserved spirometry were included; 1067 (93.6%) completed at least one follow-up lung function assessment. One standard deviation decrease in PiSlope was associated with accelerated decline in prebronchodilator forced expiratory volume in 1 second (FEV 1 ) (adjusted difference 5 mL/year, 95% confidence interval CI 1–9, p=0.007) and postbronchodilator FEV 1 (adjusted difference 4 mL/year, 95% CI 0–9, p=0.033), and increased airflow obstruction risk (unadjusted odds ratio OR 1.21, 95% CI 1.01–1.36, p =0.038). Q2–Q4 had accelerated decline in prebronchodilator FEV 1 and FEV 1 % predicted than Q1 (all p<0.05). The third-year risk of airflow obstruction progression was higher in Q2 (adjusted OR 2.40, 95% CI 1.13–5.08, p=0.022), Q3 (adjusted OR 1.71, 95% CI 0.77–3.82, p=0.188), and Q4 (adjusted OR 2.04, 95% CI 0.92–4.53, p=0.078) than in Q1. Conclusion Lower PiSlope was associated with faster lung function decline and increased airflow obstruction risk in participants with preserved spirometry, but the association between PiSlope and progression to airflow obstruction was not significant after adjustment.