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

Airway remodelling precedes airflow obstruction in COPD. Pi10 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.

Participants with preserved spirometry with complete baseline questionnaires, spirometry and chest computed tomography were enrolled from a 3-year prospective Early Chronic Obstructive Pulmonary Disease (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.

1140 participants with preserved spirometry were included and 1067 (93.6%) completed at least one follow-up lung function assessment. One standard deviation decrease in PiSlope was associated with accelerated decline in pre-bronchodilator forced expiratory volume in 1 s (FEV₁) (adjusted difference 5 mL·year^-1, 95% CI 1-9 mL·year^-1; p=0.007) and post-bronchodilator FEV₁ (adjusted difference 4 mL·year^-1, 95% CI 0-9 mL·year^-1; p=0.033), and increased airflow obstruction risk (unadjusted: OR 1.21, 95% CI 1.01-1.36, p =0.038; adjusted: OR 1.13, 95% CI 0.87-1.32, p=0.307). Q2-Q4 had accelerated decline in pre-bronchodilator FEV₁ and FEV₁ % predicted, compared with 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.

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.