AB001. Predictors of mortality in hospitalized patients with idiopathic pulmonary fibrosis-acute exacerbation

Background: Idiopathic pulmonary fibrosis (IPF) is an irreversibly progressive disease leading all patients to death. IPF-acute exacerbations (IPF-AE), histopathologically diffuse alveolar damage (DAD) upon usual interstitial pneumonia (UIP) and clinically acute respiratory distress syndrome (ARDS) upon IPF, constitute the most common deadly complication. Outcome of this devastating event remains unpredictable. We aimed to investigate mortality predictors in hospitalized patients with IPF-AE.

Methods: Hospitalized IPF-AE patients from 10/2013–06/2016 were included in the study. All patients fulfilled IPF-AE International Criteria [history of UIP-IPF, new pulmonary infiltrates in chest computed tomography (ground glass opacities and/or consolidation upon reticular or honeycomb pattern consistent with UIP), deterioration of dyspnea the last 30 days, exclusion of reversible causes]. Upon admission leukocytes, hematocrit, C-reactive protein (CRP), procalcitonin (pCT), albumin, uric acid, lactate dehydrogenase, troponin, pro-Brain natriuretic peptide (pro-BNP), the ratio of partial pressure of oxygen in arterial blood to fraction of inspired oxygen (PaO₂/FiO₂) were measured. Demographic and functional data, smoking, immunosuppressive treatment, co-morbidities, prior hospital admission, GAP staging (gender-age-physiology score) and outcome of IPF-AE were reported. Data were statistically analyzed.

Results: Sixty-two IPF-AE patients were studied: 17 (27.4%) died while being hospitalized [median age (IQR) 69.0 years (60.0, 79.0)], 45 (72.6%) survived [median age (IQR) 73.0 years (66.0, 78.0)]. Patients who died had received more frequently immunosuppressive treatment (47% vs. 11.1%, P=0.002) and had significantly higher leukocytes [median value (MV) (IQR) 10.750 K/µL (10.150, 13.600) vs. 8.240 (7.300, 10.030), P<0.001], pCT [MV (IQR) 0.1 ng/mL (0.0, 0.6) vs. 0.1 (0.0, 0.1), P=0.021], troponin [MV (IQR) 24.6 pg/mL (15.2, 49.1) vs. 10.4 (5.9, 17.4), P=0.001], pro-BNP [MV (IQR) 657.0 pg/µL (165.7, 2155.0) vs. 185.4 (66.0, 361.2), P=0.030] levels and lower albumin [MV (IQR) 3.6 g/dL (3.4, 4.0) vs. 4.0 (3.8, 4.2), P=0.012] and PaO₂/FiO₂ ratio [MV (IQR) 144.0 (100.0, 160.0) vs. 247.0 (203.0, 271.0), P<0.001]. In multivariate analysis, PaO₂/FiO₂ on admission remained the only independent predictor of higher mortality risk (OR 0.982, 95% CI: 0.968 to 0.996).

Conclusions: Based on the present study, previous immunosuppressive treatment, indices of inflammatory response and of cardiac impairment predicted worse outcome. As expected, severity of ARDS reflected by PaO₂/FiO₂ was the strongest independent predictor of mortality in IPF-AE hospitalized patients.

Keywords: Idiopathic pulmonary fibrosis (IPF); acute respiratory distress syndrome (ARDS); interstitial pneumonia