Acute exacerbation of chronic fibrosing interstitial pneumonia in patients receiving antifibrotic agents: incidence and risk factors from real-world experience

Background and objective Here, we present real-world data on the incidence and risk factors of acute exacerbation (AE) in patients with chronic fibrotic interstitial pneumonia (CFIP) treated with antifibrotic agents, which has been previously poorly documented. Methods We retrospectively examined clinical characteristics, incidence and risk factors of AE in a cohort of 100 patients with CFIP ( n = 75, idiopathic pulmonary fibrosis [IPF]; n = 25, other conditions), all of whom received antifibrotic agents in a real-world setting. Results The median follow-up was 17.4 months (interquartile range [IQR], 6.6 to 26.7 months). During the follow-up periods, 21 patients experienced AE after starting antifibrotic agents. The estimated 1-, 2-, and 3-year AE incidence rates were 11.4% (95% confidence interval [95%CI], 6.2–20.3%), 32% (95%CI, 20.7–47.4%), and 36.3% (95%CI 23.5–53.1%), respectively. Decreased baseline lung function (forced vital capacity and carbon monoxide diffusing capacity of the lung), existence of pulmonary hypertension estimated from an echocardiogram, higher Interstitial Lung Disease- Gender, Age, and Physiology (ILD-GAP) score, supplementary oxygen, and concomitant corticosteroid and proton-pump inhibitor (PPI) use upon starting the antifibrotic agent were risk factors of AE. Concomitant corticosteroid and PPI use and corticosteroid dose were risk factor of AE in a multivariate Cox regression hazard model adjusting for ILD-GAP score. Conclusion AE of CFIP is more common in patients with physiologically and functionally advanced disease under antifibrotic agents. Prudent use of corticosteroids and PPIs when initiating antifibrotic agents may be recommended. Further studies are warranted.