Clinical course and outcomes of acute exacerbation of fibrosing interstitial lung disease

Abstract

<b>Background:</b> Despite the clinical importance of acute exacerbations of fibrosing interstitial lung disease (AE-FILD), there are few large-scale reports about the clinical courses of AE-FILD. <b>Objectives:</b> The aim of this study was to obtain a detailed understanding of clinical courses of AE-FILD and to identify areas with scope for improving the management. <b>Methods:</b> This is a multicenter retrospective cohort study. We enrolled patients admitted with the diagnosis of AE-FILD between January 2012 and December 2019. We investigated the clinical course of acute-phase after AE-FILD. We have classified the clinical courses into four major categories; (1) consistent improvement (responder group) (2) not respond to treatment at all (non-responder group), (3) temporary improvement after initial therapy but re-worsening (2nd-attack group), and (4) complications leading to death after the temporary improvement after initial therapy (complication group). <b>Results:</b> We analyzed 384 patients and 148 patients (38.5%) died within 90 days after the development of AE-FILD. There were 224 (58.3%) in the responder group, 84 (21.9%) in the non-responder group, 47 (12.2%) in the 2nd-attack group, 19 (4.9%) in the complication group, and 10 (2.6%) in the unknown group, respectively. Of 47 patients who developed 2nd-attack, 35 (74.5%) had died. Univariate analysis revealed that high LDH and CRP levels, low P/F ratio (&lt;200), and 2nd-attack were significantly associated with 90-day mortality. <b>Conclusions:</b> Our study showed that AE-FILD followed a heterogenous clinical course and revealed that 2nd-attack was a common and poor prognostic condition.