Acute exacerbation in antineutrophil cytoplasmic antibody-associated interstitial lung disease: Clinical features and risk factors

Abstract

Background: Acute exacerbation (AE) is a life-threatening clinical event that occurs during the clinical course of idiopathic pulmonary fibrosis (IPF). Several studies have reported that AE also occurs in interstitial lung disease (ILD) other than IPF. However, the incidence, clinical features, risk factors for AE, and major causes of death in antineutrophil cytoplasmic antibody (ANCA)-associated ILD (ANCA-ILD) patients have not been well established.

Methods: We retrospectively reviewed the data of 54 ANCA-ILD patients and 304 IPF patients. We investigated the frequency of AE, post-AE prognoses, risk factors for AE, and major causes of death in ANCA-ILD patients. We also compared the data of ANCA-ILD with that of IPF.

Results: Fourteen (25.9%) ANCA-ILD patients and 84 (27.6%) IPF patients developed AE. The median survival times (MSTs) after AE in ANCA-ILD and IPF patients were 35.5 and 60 days, respectively (p = 0.588, log-rank test). In a multivariate analysis, the percentage of predicted forced vital capacity (%FVC) [O.R. 0.750 (95% CI 0.570, 0.986), p < 0.01] and serum C-reactive protein (CRP) [O.R. 2.202 (95% CI 1.037, 4.674), p < 0.01] were independent risk factors for AE. AE was the most frequent cause of death in ANCA-ILD and IPF patients.

Conclusion: ANCA-ILD patients could develop AE, and the frequency of AE in ANCA-ILD is similar to that in IPF. AE is the most frequent cause of death in ANCA-ILD patients. A low %FVC and a high serum CRP level were independent predictive factors for AE in ANCA-ILD. The prognosis after AE in ANCA-ILD was poor, as it was in IPF.

Keywords: Acute exacerbation; Antineutrophil cytoplasmic antibody (ANCA); Interstitial lung disease; Prognosis; Risk factor.