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Impulse oscillometry-derived respiratory mechanical abnormalities and fibrotic disease progression in interstitial lung disease: a single-center cohort study

Year: 2026

Type: article

Abstract: Objective: To examine whether continuous impulse oscillometry (IOS)-derived respiratory mechanical measures are associated with subsequent fibrotic disease progression in interstitial lung disease (ILD). Methods: In this single-center ambispective cohort study, 255 adults with fibrotic ILD underwent baseline spirometry, diffusing capacity testing and IOS. Fibrotic disease progression was defined using a PPF-like composite requiring at least two of three domains (worsening respiratory symptoms, physiological progression and radiological progression) within a 9-15-month assessment window. All IOS parameters were analyzed continuously using Firth penalized logistic regression, adjusted for age, sex, height and baseline FVC % predicted. X5 was additionally assessed using continuous scaling and restricted cubic splines. ROC analyses, non-IPF sensitivity analyses, and bootstrap validation were exploratory. Results: Fibrotic disease progression occurred in 41 of 255 patients (16.1%). A 1-SD worsening in X5 was associated with higher odds of progression (OR 8.89, 95% CI 4.66-19.47; P<0.001), as were AX (OR 1.67, 95% CI 1.22-2.38; P = 0.001) and Fres (OR 1.61, 95% CI 1.11-2.36; P = 0.012). Each 0.01 kPa·s/L increase in X5 was associated with lower odds of progression (adjusted OR 0.67, 95% CI 0.59-0.76; P<0.001), and the X5-progression association was nonlinear (P for nonlinearity<0.001). After exclusion of IPF, X5 and AX remained associated with progression. Bootstrap validation showed improved discrimination after adding AX or X5, but did not constitute external validation. Conclusions: Continuous IOS measures, particularly X5 and AX, were associated with subsequent fibrotic disease progression in this single-center ILD cohort, with a weaker signal for Fres. The X5 association was nonlinear and remained evident after exclusion of IPF. ROC-derived thresholds were unstable and should be considered exploratory. These findings support further evaluation of oscillometric respiratory-mechanical abnormalities in larger externally validated cohorts but do not establish clinically applicable predictive thresholds.

Source: Frontiers in Physiology

DOI: 10.3389/fphys.2026.1962001