Risk factors of acute exacerbation of idiopathic pulmonary fibrosis

Although acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) is a well known clinical condition, predicting risk factors remain unknown. We evaluated the frequency, risk factors and impact on survival of AE-IPF.

We retrospectively studied patients diagnosed with IPF based on the criteria of the ATS/ERS consensus statement and followed them for periods of more than 3 years except in dead cases. Initial characteristics including the level of dyspnoea, which was assessed with the modified Medical Research Council (MRC) scale, and decline of forced vital capacity (FVC) defined by at least 10% decline at 6 months, were evaluated as possible risk factors for AE.

Seventy-four patients with IPF were studied. One-year, two-year, and three-year incidence of AE were 8.6%, 12.6%, and 23.9%, respectively. Multivariate analysis revealed that higher body mass index (BMI) [hazard ratio (HR), 1.20; 95% confidence interval (CI), 1.03-1.40], higher modified MRC scale [HR, 2.93; 95% CI, 1.46-5.85], and a decline in FVC at 6 mounths [HR, 0.97-2.60 (per mo); 95% CI, 1.01-7.45] were independent risk factors for AE-IPF. The causes of death were assessed to be AE in 20 of 57 expired patients. A stepwise multivariate Cox regression model evaluating AE-IPF, adjusted for %FVC and decline in FVC, demonstrated a statistically significant impact on overall survival [HR, 2.79; 95% CI, 1.59-4.88; p < 0.001].

These data suggest that initial high modified MRC scale, high BMI, and decline in FVC at 6 months were significant independent risk factors for AE-IPF. AE was an independent prognostic factor in IPF.