Small Airways Disease Functional Assessment in Idiopathic Pulmonary Fibrosis (SWIFT-IPF)

To evaluate the percentage of patients with IPF at the time of diagnosis, before the initiation of antifibrotic therapy, with small airway disease measured by the nitrogen washout test (assessing the following functional parameters: phase 3 slope, closing volume, closing capacity, closing volume/vital capacity, closing capacity/total lung capacity, and phase 4 slope).

To evaluate the relationship between CT features (radiologic pattern type, presence/absence of mediastinal lymphadenopathy, presence/absence of any type of emphysema involving ≥5% of total lung volume, extent of disease, disease progression, air trapping, black lung) and functional parameters indicative of small airway disease.

To compare the indices of small airway dysfunction and the prevalence of small airway disease in patients with IPF and age-matched healthy subjects (without respiratory comorbidities).

To study the relationship between clinical and epidemiological characteristics of the cohort and the presence and severity of small airway disease

To compare the prevalence of small airway disease in patients with IPF and concomitant emphysema (combined pulmonary fibrosis and emphysema, CPFE), defined as the presence of any type of emphysema involving ≥5% of total lung volume, with patients with IPF alone.

To evaluate the correlation between functional characteristics: forced expiratory flow at 25-75% of vital capacity (FEF25-75), forced vital capacity (FVC) and diffusing of the lung for carbon monoxide (DLCO) with parameters of small airway dysfunction from the Single Breath Nitrogen (SBN2) test, as well as disease extent indices on chest CT-scan

To evaluate the relationship between exercise performance (meters, oxygen saturation nadir), assessed by the six-minute walk test distance, and the presence and severity of small airway disease

To evaluate the relationship between the degree of dyspnea, measured by the modified Medical Research Council (mMRC) scale, and the presence and severity of small airway disease.

To evaluate the clinical and functional characteristics of IPF patients with different alterations in the DLCO subcomponents (alveolar volume - VA <80% predicted, Transfer Coefficient of CO - KCO <80% predicted, ventilation inhomogeneity - VA/Total Lung Capacity (TLC) <0.8)

To evaluate the relationship between different scores as the Gender Age Physiology (GAP) index, Composite Physiologic Index (CPI) , the King's Brief Interstitial Lung Disease (KBILD) score and the University of California San Diego (UCSD) Shortness of Breath Questionnaire, and the presence and severity of small airway disease;

Evaluate presence and variation of small airway dysfunction parameters from the Single Breath Nitrogen (SBN2) test in IPF patients after one year of antifibrotic therapy.

To evaluate the percentage of patients with IPF with tidal expiratory flow limitation measured by means of Negative Expiratory Pressure (NEP), at the time of diagnosis, before the initiation of antifibrotic therapy and after one year of therapy with antifibrotic treatment