Comparison of anti-aminoacyl-tRNA synthetase antibody-related and idiopathic non-specific interstitial pneumonia.

Background and Purpose: Patients with anti-aminoacyl-tRNA synthetase (ARS) antibodies frequently experience complications of interstitial pneumonia (ARS-IP), and the computed tomography (CT) of ARS-IP frequently shows nonspecific interstitial pneumonia (NSIP) pattern. The CT pattern of ARS-IP might be different from that of idiopathic IP. However, the clinical differences in patients with ARS-IP and idiopathic IP showing the similar CT patterns have not yet been well studied. The objective of this study was to evaluate the clinical differences between patients with ARS-NSIP and idiopathic NSIP (I-NSIP).
Methods: Two groups of 34 patients each, with ARS-NSIP and I-NSIP, who visited Hiroshima University Hospital between January 2005 and December 2017, were enrolled. Clinical features and outcomes were retrospectively compared between the two groups.
Results: The ARS-NSIP group included more female patients and significantly younger patients than the I-NSIP group. The percentage of lymphocytes in bronchoalveolar lavage fluid (BALF) was significantly higher, and the CD4/CD8 ratio in BALF was significantly lower in the ARS-NSIP group compared with the I-NSIP group. The proportion of patients with traction bronchiectasis detected by CT was significantly higher in I-NSIP compared with ARS-NSIP. The number of patients who received corticosteroid and/or immunosuppressant therapy was significantly larger in the ARS-NSIP group than in the I-NSIP group. In addition, the patients in the I-NSIP group who underwent the immunosuppressive therapy demonstrated shorter survival than those who underwent no treatment; this tendency was not observed in the ARS-NSIP group. The 10-year survival rate of patients in the ARS-NSIP group was significantly higher than that of patients in the I-NSIP group (91.8% vs. 43.0%; log-rank, p = 0.012). The multivariate survival analysis revealed that positive anti-ARS antibody was an independent favorable prognostic factor in the patients with NSIP (OR, [95% CI]:0.12 [0.02-0.55], p = 0.013).
Conclusions: Patients with ARS-NSIP had a significantly better prognosis than those with I-NSIP; this may be associated with the sensitivity to immunosuppressive therapies, and the different findings of BALF and HRCT between the two groups.
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