HRQoL assessment using KBILD in fibrotic ILDs receiving antifibrotic therapy: a prospective longitudinal study

Background Patients with fibrotic interstitial lung diseases (ILDs) experience impaired health-related quality of life (HRQoL). The King's Brief Interstitial Lung Disease (KBILD) questionnaire was designed to evaluate disease-specific HRQoL; however, its practical application in real-world clinical settings has not been thoroughly investigated. Methods This prospective longitudinal study included 289 patients with fibrotic ILD initiated antifibrotic therapy. Their HRQoL was evaluated using the KBILD questionnaire at baseline, 6 months, and 1 year. A total of 289, 164, and 159 patients completed the KBILD assessment at the aforementioned time points, respectively. The associations between the KBILD scores, clinical parameters, and mortality risk were evaluated. Results The KBILD Total score demonstrated a moderate correlation with dyspnea scale but a weak or no correlation with pulmonary function test parameters and ILD etiology. Interestingly, more than 20% of the patients showed significant improvement (≥5 points) at 6 months and 1 year. A lower baseline KBILD Total score was associated with disease progression and reduced survival, independent of the ILD–gender–age–physiology index. In addition, longitudinal assessment showed that the cross-sectional KBILD Total score at 6 months and 1 year and longitudinal decreases in the KBILD Total score at 1 year were associated with increased mortality risk. Conclusion Antifibrotic therapy has a positive impact on HRQoL in a subset of patients with fibrotic ILDs. Repeated KBILD assessment may aid in monitoring mortality risk, independent of lung function tests.