THU0677 IDENTIFICATION OF PREVALENCE, PROGNOSTIC FACTORS, AND OUTCOMES OF PATIENTS WITH INTERSTITIAL PNEUMONIA WITH AUTOIMMUNE FEATURES: A SINGLE CENTER LARGE-SCALE OBSERVATIONAL COHORT STUDY
Authors: Okinori Murata, Katsuya Suzuki, Nobuhito Sasaki, Makoto Maemondo
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Patients with idiopathic interstitial pneumonia (IIP) may have features of connective tissue diseases (CTDs). The term interstitial pneumonia with autoimmune features (IPAF) has been recently proposed for such patients. A few studies have been reported in prevalence of IPAF which was varied from 7.3% to 34.1% [1, 2]. Factors reported to indicate a poor prognosis in IPAF include age, smoking history, organizing pneumonia pattern in HRCT, anti-RNP antibody positivity, decline in%DLCO and presence of a multi-compartment feature within the morphological domain [2, 3]. To date, however, no study has comprehensively described prevalence of IPAF and factors of exacerbation. <h3>Objectives:</h3> The aim of study was to identify of prevalence of IPAF in patients with interstitial lung disease, prognostic factors for exacerbation in patients with IPAF, and compared outcomes among patients with IPAF, IIP, and CTD-ILD. <h3>Methods:</h3> Six hundreds- and seventy-two patients who visited our department between April 2009 and March 2018 and were evaluated by chest HRCT scan. Then, they were clinically and radiologically diagnosed as having interstitial lung disease (ILD), IIP or connective tissue diseases associated ILD were enrolled. We applied IPAF criteria to these patients. Then, we purified 68 patients. The prognostic factors for exacerbation were prospectively calculated and statistically analyzed using clinical, laboratory and imaging data collected from medical records. <h3>Results:</h3> Prevalence of IPAF was 10.1%. Of 68 patients with IPAF, 60% were women and mean age at diagnosis was 64.2 ± 13.8 years old. Mean observation period was 27.1 ± 29.6 months. Smoking history was 42.6% (n=29). Treatment including oral glucocorticoid or/and immunosuppressant use were 44.1% (n=30). Exacerbation rate was 25% (n=17). Overall death rate was 5.9% (n=4) and respiratory death rate was 2.9% (n=2). Comparison of characteristics at diagnosis between the exacerbation group and non-exacerbation group showed that the exacerbation group had a significantly elevated rate of smoking history, KL-6, and SP-D (P=0.01, 0.006, and 0.03, respectively). We then analyzed transition of KL-6 in patients with IPAF, IIP, or CTD-ILD. KL-6 at baseline in patients with IPAF (1212 ± 1626 U/mL) was higher than those with IIP and significantly higher than those with CTD-ILD (1030 ± 1027 U/mL(P=0.69) and 829.5 ± 1002 U/mL(P=0.024)), while exacerbation rate in patients with IPAF (25%) was significantly lower than those in IIP patients (40%) and CTD-ILD patients (41%) (P=0.03). Furthermore, KL-6 in IPAF patients gradually decreased during course and was lower than IIP or CTD-ILD patients at 84 months from diagnosis. <h3>Conclusion:</h3> Our large-scale observational cohort study revealed prevalence of IPAF in patients with ILD and identified three baseline factors associated with exacerbation in the patients with IPAF and suggested that IPAF might have a better prognosis than IIP or CTD-ILD. <h3>References:</h3> [1] Respir Med. 2017; 123:56–62,&nbsp; [2] Eur Respir J. 2016; 47:1622–1624,&nbsp; [3] Clin Rheumatol. 2018 Apr 18 <h3>Disclosure of Interests:</h3> None declared