Acute exacerbation of unclassifiable idiopathic interstitial pneumonia: comparison with idiopathic pulmonary fibrosis
Noriyuki Enomoto, Hyogo Naoi, Yuya Aono, Mineo Katsumata, Yasuoki Horiike, Hideki Yasui, Masato Karayama, Hironao Hozumi, Yuzo Suzuki, Kazuki Furuhashi, Tomoyuki Fujisawa, Naoki Inui, Yutaro Nakamura, Takafumi Suda
Abstract
Background: Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) is well known as a life-threatening condition during its clinical course. However, the clinical features and prognosis in AE of unclassifiable idiopathic interstitial pneumonia (AE-UCIIP) remain to be elucidated. The aim of this study was to clarify the clinical features and prognosis of AE-UCIIP compared with those of AE-IPF. Methods: In 187 patients with UCIIP or IPF, 64 patients with AE-UCIIP or AE-IPF, who were diagnosed and treated at our hospital, were retrospectively evaluated. Results: A total of 24 patients with AE-UCIIP were significantly older ( p = 0.011), included more women ( p < 0.001) and never-smokers ( p < 0.001), and showed fewer lung lesions on high-resolution computed tomography ( p = 0.006) than 40 patients with AE-IPF. Incidence of AE-UCIIP was 10.29%/year and was significantly higher than in AE-IPF (Gray’s test, p = 0.008). Prognosis of AE-UCIIP was as poor as that of AE-IPF (log-rank, p = 0.681). Percent-predicted forced vital capacity (%FVC) [hazard ratio (HR) 0.934, p = 0.045], and GAP stage within 12 months before AE (HR 3.530, p = 0.023), and partial pressure arterial oxygen/fraction of inspired oxygen (PaO 2 /FiO 2 ) ratio at AE (HR 0.998, p = 0.016) were significant prognostic factors. Finally, commencement of long-duration (⩾12 h) direct hemoperfusion with a polymyxin B-immobilised fibre column (PMX-DHP) within 2 days after admission significantly improved survival (log-rank, p = 0.038) and was a significant prognostic factor (HR 0.175, p = 0.0039) in AE-UCIIP. Long-duration PMX-DHP showed favourable treatment effects even in the combined group of patients with AE-UCIIP or AE-IPF (log-rank p = 0.002; HR 0.328, p = 0.006). Conclusions: Patients with AE-UCIIP were older and included more women and never-smokers than those with AE-IPF. Prognosis of AE-UCIIP was as poor as that of AE-IPF. The reviews of this paper are available via the supplemental material section.