Compare three diagnostic criteria of progressive pulmonary fibrosis

Abstract Background and objective: In patients with fibrotic interstitial lung disease (ILD), a progressive fibrosing phenotype (PPF) typically demonstrates worsening respiratory symptoms, lung function decline and continuing fibrosis. The goal of this study was to compare the three different diagnostic criteria of PPF. Methods: Except for idiopathic pulmonary fibrosis, all consecutive adult patients with fibrotic ILD were retrospectively examined for the three predefined diagnostic criteria of PPF. The three criteria assess the disease progression in preceding 6 (half-year), 12 (one-year) and 24 (two-year) months respectively. The clinical characteristics, decline in predicted percent of forced vital capacity (FVC%) and survival of the three groups were compared, followed by determination of risk factors for mortality. Results: We identified 246 patients by half-year standard, 154 patients by one-year standard and 281 patients by two-year standard. Among them, 95% of patients in one-year group were also included in two-year group. The average one-year decline in FVC% was -1.0%, -2.7%, and -4.1% for half-year, one-year and two-year group respectively. The 4-year survival rate was 74% in half-year group, 66% in one-year group and 62% in two-year group. In multivariate Cox model, only baseline DLCO%<50% was correlated with mortality, with a hazard ratio of 3.4 (95% CI 1.1-10.6, P=0.03). Conclusion: In the current situations, both the one-year and two-year criterion are the reasonable choice to define PPF both in researches and clinical practice, and DLCO% is an independent predictor for mortality of PPF.