Clinical Significance of Serum Autoantibodies in Idiopathic Interstitial Pneumonia

Abstract

Although autoantibodies are routinely screened in patients with idiopathic interstitial pneumonia, there are no reliable data on their clinical usefulness. The aim of this study was to investigate the prognostic value of autoantibodies for predicting the development of new connective tissue disease in these patients and also mortality. We conducted retrospective analysis of the baseline, and follow-up data for 688 patients with idiopathic interstitial pneumonia (526 with idiopathic pulmonary fibrosis, 85 with nonspecific interstitial pneumonia, and 77 with cryptogenic organizing pneumonia) at one single tertiary referral center. The median follow-up period was 33.6 months. Antinuclear antibody was positive in 34.5% of all subjects, rheumatoid factor in 13.2%, and other specific autoantibodies were positive between 0.7%-6.8% of the cases. No significant difference in patient survival was found between the autoantibody-positive and -negative groups. However, the presence of autoantibodies, especially antinuclear antibody with a titer higher than 1:320, was a significant predictor for the future development of new connective tissue diseases (relative risk, 6.4), although the incidence was low (3.8% of all subjects during follow-up). In conclusion, autoantibodies are significant predictors for new connective tissue disease development, although they have no prognostic value.

Utility of Anti-DSF70 Antibodies to Predict Connective Tissue Disease in Patients Originally Presenting with Idiopathic Interstitial Pneumonia

“…In our study, positive ANAs were observed in 47% of NSIP and 32% of IPF patients. The observed frequency is consistent with the existing literature [25]. In our CTD-ILD patients, ANA positivity was seen in 68% which is relatively low for a CTD cohort.…”

Role of Autoantibodies in the Diagnosis of Connective-Tissue Disease ILD (CTD-ILD) and Interstitial Pneumonia with Autoimmune Features (IPAF)

“…The detection of autoantibodies may assist the diagnosis of an unrecognised CTD in specialist ILD clinics with a reported frequency of 4% to 19% [7,37,38,39]. In established CTD-ILD, autoantibodies can also allow more precise classification between the various CTDs presenting with similar clinical, radiological and/or histopathological features [39].…”

Organizing Pneumonia Preceding Rheumatoid Arthritis

“…However, in so-called “occult CTDs,” the clinical significance of these classifications and evidence for the usefulness of autoantibodies have not yet been established. Meanwhile, in this review, we found that patients with OP preceding RA have a greater prevalence of RF or CCP compared with previous reviews of patients with cryptogenic and secondary OP (RF, 3.4–19.7%; CCP, 4.2%) [12–14]. Early identification of RA is becoming increasingly important because early therapy has been reported to preserve joint function [15].…”