Background/Purpose: 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. Factors reported to indicate a poor prognosis in IPAF include age, smoking history, non-specific interstitial pattern in HRCT, anti-RNP antibody positivity, decline in %DLCO and presence of a multi-compartment feature within the morphological domain [1-3]. To date, however, no study has comprehensively described outcomes over a long-term period and factors of exacerbation. The aim of study was to identify prognostic factors for exacerbation in patients with IPAF, and compare long-term outcomes among patients with IPAF, IIP, and CTD-ILD.

Methods: Six hundreds- and seventy-two patients who visited our department between April 2009 and March 2019 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 and then purified 68 patients. The prognostic factors for exacerbation were prospectively calculated and statistically analyzed using clinical, laboratory and imaging data collected from medical records.

Results: 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. Exacerbation rate was 25% (n=17). Overall death rate was 5.9% (n=4). 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, KL-6, and SP-D (P=0.034, 0.016, and 0.007). When we compared characteristics at diagnosis between the treatment group and non-treatment group in patients with IPAF, and those between the exacerbation group and non-exacerbation group in IPAF patients with treatment, the treatment group was significantly associated with signs of mechanic’s hands, arthritis, anti-SS-A antibody positivity, and anti-ARS antibody positivity (P=0.009, 0.05, 0.05, and 0.007), and the exacerbation group in IPAF patients with treatment had a significantly elevated rate of smoking and KL-6 (P=0.008 and 0.019). When we compared long-term outcomes among patients with IPAF, IIP, and CTD-ILD, 5-year non-exacerbation rate in IPAF patients with treatment, those without treatment, CTD-ILD patients, and IIP patients was 36.5%, 83.3%, 59.5%, and 28.3%, respectively. (Figure 1)

Conclusion: Our large-scale cross-sectional cohort study identified unique prognostic factors of exacerbation and long-term outcome in patients with IPAF.
References: [1] BMC Pulmonary Medicine. (2017), [2] Eur Respir J. (2016), [3] Clin Rheumatol. (2018)

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-outcome-and-prognostic-factors-of-patients-with-interstitial-pneumonia-with-autoimmune-features-a-single-center-large-scale-observational-cohort-study/