Background: Although acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) is a well known clinical condition, predicting risk factors remain unknown. Recent studies reported that various baseline factors, and at least 10% decline in FVC at six months were reported as risk factor for AE (Sarcoidosis Vasc Diffuse Lung Dis 2010;27:103-110). We sought to evaluate the risk factors of AE by analyzing our phase III clinical trial of pirfenidone for patients with IPF (n=275) (Eur Respir J 2010; 35: 821-9). Methods: Baseline characteristics including age, sex, smoking, BMI, dyspnoea grade (Hugh-Jones classification), AaDO2, PaO2,%VC,%DLco, KL-6, SP-A, SP-D were evaluated as possible risk factors for AE. Decline of VC≥10% within 6 months was also evaluated. In addition, effect of pirfenidone therapy was also evaluated. Results: During 52 weeks, 14 patients experienced AE-IPF. Univariate analysis by Cox proportion hazards model were as follows: age (HR, 0.982, p=0.642), sex (HR, 1.505, p=0.489) smoking (HR, 0.464, p=0.168), BMI (HR, 0.935, p=0.460), dyspnea grade (HR, 1.763, p=0.168), AaDO2 (HR, 1.047, p=0.069), PaO2 (HR, 0.955, p=0.110),%VC (HR, 0.971, p=0.078),%DLco (HR, 0.994, p=0.714), KL-6 (HR, 1.000, p=0.698), SP-A (HR, 0.998, p=0.776), SP-D (HR, 1.000, p=0.875), pirfenidone treatment (HR, 1.211, p=0.732). Decline of VC was a significant risk factor for AE-IPF (HR, 3.780, p=0.014). Stepwised multivariate analysis revealed that initial AaDO2 (HR, 1.055, p=0.045) and decline in VC within 6 months (HR, 3.951, p=0.012) were significant risk factors for AE-IPF. Conclusions: Baseline higher AaDO2 and decline of VC≥10% within 6 months are significant risk factors of AE-IPF.
Taniguchi et al. (Thu,) studied this question.
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