Health-related quality of life assessment using KBILD in fibrotic interstitial lung diseases 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 dyspnoea scale but a weak or no correlation with pulmonary function test parameters and ILD aetiology. 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.