Quality of life in patients with hypersensitivity pneumonitis and with idiopathic pulmonary fibrosis in real-life clinical practice.

Background: Interstitial lung diseases (ILDs) significantly impair health-related quality of life (HRQL). While HRQL in idiopathic pulmonary fibrosis (IPF) is well studied, data on hypersensitivity pneumonitis (HP) remain limited despite comparable clinical impacts. This study evaluates HRQL in patients with IPF and HP using the King's Brief Interstitial Lung Disease Questionnaire (K-BILD) and EuroQoL 5-Dimension 5-Level Questionnaire (EQ-5D-5L) and examines factors associated with reduced HRQL. Methods: This longitudinal, observational study included 153 patients [48 IPF, 105 HP, including 72 fibrotic HP (fHP), of whom 32 had usual interstitial pneumonia (UIP) pattern (fHP + UIP)]. Demographic, anamnestic and clinical data, HRQL, respiratory function, echocardiography parameters, dyspnea [modified Medical Research Council (mMRC) dyspnea scale], cough [visual analog scale (VAS scale), Leicester Cough Questionnaire (LCQ)], six-minute walk test (6MWT) results, and high-resolution computed tomography (HRCT) changes were assessed at baseline and after 12 months. Statistical analyses included non-parametric tests, correlation, regression, and receiver operator characteristic (ROC)-curve evaluation to identify factors associated with reduced HRQL. Results: IPF patients demonstrated more severe dyspnea and reduced exercise capacity compared to HP, while overall lung function parameters and cough-related measures showed comparable results between the groups. Within the HP cohort, fibrotic forms were associated with greater symptom burden, more advanced physiological impairment, longer diagnostic delay. A statistically significant relationship between the K-BILD and the EQ-5D-5L was found. HRQL assessed by the K-BILD questionnaire did not differ significantly between patients with IPF and those with HP. In contrast, EQ-5D-5L scores were significantly lower in IPF compared to HP, although no significant differences were observed between IPF and fHP. Both questionnaires demonstrated significant differences in HRQL between fHP and nfHP, while no differences were found between fHP patients with and without UIP pattern. Additionally, HRQL measured by K-BILD was associated with gender-age-physiology (GAP) stage in both IPF and HP cohorts. HRQL according to the K-BILD was mainly associated with cough severity (LCQ), 6-minute walk distance (6MWD), dyspnea intensity (mMRC) and lung function parameters [forced vital capacity (FVC)]. For the EQ-5D-5L, the main predictors of lower HRQL were reduced exercise capacity (6MWD) and higher cough burden (LCQ). According to the results of ROC analysis, the predictors of HRQL score less than 50 points (K-BILD): cough score <13 points (LCQ) and dyspnea score of ≥3 (mMRC). Conclusions: Patients with fHP, especially with UIP pattern, exhibit similar clinical features and functional decline as seen in IPF patients. Cough severity, dyspnea, and exercise capacity were the strongest predictors of reduced HRQL, highlighting the need for comprehensive symptom assessment and individualized management in both IPF and HP. K-BILD and EQ-5D-5L are reliable tools for assessing HRQL and identifying significant clinical and functional factors.