Rationale: Anti-aminoacyl transfer RNA synthetase antibodies (anti-ARS) are a group of myositis-specific autoantibodies that are detected in the sera of patients with polymyositis and dermatomyositis (PM/DM) and also in those of patients with idiopathic interstitial pneumonias without any connective tissue disease (CTD), including PM/DM. Although we reported the clinical characteristics of interstitial lung disease with anti-ARS antibodies (ARS-ILD) with and without PM/DM, the long-term prognosis of ARS-ILD remains undetermined. As our previous studies revealed that ARS-ILD without PM/DM was similar to CTD-associated ILD, and that ARS-ILD with PM/DM was radiologically suggestive of a nonspecific interstitial pneumonia (NSIP) pathological pattern, we hypothesized that the prognosis of ARS-ILD might be distinct from that of idiopathic pulmonary fibrosis (IPF) without anti-ARS.
Objectives: To elucidate the long-term outcome of ARS-ILD with and without PM/DM and compare it to that of IPF.
Methods: A two-center retrospective study was conducted. The study population comprised 36 patients with ARS-ILD (8 with PM, 12 with DM, and 16 without myositis throughout the course), 100 patients with IPF without anti-ARS, and 7 patients with NSIP without anti-ARS. The presence of anti-ARS was determined by RNA immunoprecipitation using the sera obtained at the time of diagnosis before specific treatment.
Measurements and main results: During the observational period (median 49 months; range, 1-114 months), 7 patients with ARS-ILD (19%; 3 with PM, 1 with DM, and 3 without PM/DM) and 51 patients with IPF (51%) died. Patients with ARS-ILD had better overall survival than those with IPF (log-rank test, P < 0.001) and similar survival compared to those with NSIP (log-rank test, P = 0.59). The prognosis for patients with ARS-ILD was similar between those with and without myositis (log-rank test, P = 0.91). At the median follow-up time of 76.5 months, 14 of the 36 patients with ARS-ILD had deteriorated. Both a decline in forced vital capacity or an initiation of long-term oxygen therapy during the course (odds ratio [OR], 5.34) and acute exacerbation (OR, 28.4) significantly increased the mortality risk.
Conclusions: The long-term outcome of ARS-ILD was significantly better than that of IPF regardless of the presence or absence of myositis.
Keywords: Autoantibodies; Connective tissue diseases; Idiopathic pulmonary fibrosis; Myositis; Survival.
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