Rationale Interstitial lung disease (ILD) can be the initial or dominant manifestation of antisynthetase syndrome (ASS), an autoimmune inflammatory myopathy with antisynthetase antibodies. Antinuclear antibody (ANA) testing is routinely performed with further detailed tests according to associated clinical features. However, ASS with prior negative ANA has been recognized. We described the characteristics of patients with ASS-ILD and determined the clinical and prognostic significance of ANA. Methods Patients with ASS and ILD at a tertiary referral center from January 2006 to November 2018 were retrospectively reviewed. Results Of 25 patients with ASS-ILD, mean age was 54 ± 15.2 years (range 18-77), and 80% were female. Extra-pulmonary features included myositis (88%), arthritis (60%), skin (52%), gastrointestinal tract (44%), pulmonary hypertension (44%) and kidney (8%). Six patients (24%) had cancer (3 breast, 1 tongue, 1 anal, and 1 parotid gland). Approximately one-half of patients had a positive ANA. Of 12 patients with ANA negativity, 8 had Jo1, 2 had PL-7, 1 had EJ, and 1 had Ku antibody. Mean forced vital capacity (FVC) was 66 ± 17.9% (range 39-98%). Average diffusing capacity of the lungs for carbon monoxide (DLCO) was moderately reduced at 50 ± 23.3% (range 12-97%). The most common chest computed tomography (CT) pattern was non-specific interstitial pneumonia (40%), followed by usual interstitial pneumonia (UIP, 32%), probable UIP (20%) and organizing pneumonia (8%). All patients were treated with immunosuppression; prednisone (96%) and mycophenolate (52%) were the most common agents used. There were no statistically significant differences in age, gender, extra-pulmonary manifestations, chest CT pattern, or rate of change in FVC and DLCO between ANA positive and negative patients. The overall mortality rate was 52% (13 patients); 62% of whom (8 patients) were ANA negative. Respiratory failure was the most common cause of death (54%). Median overall survival time was 12 years (SD 2.83, 95% CI 6.45-17.55). There was no significant survival difference between ANA positivity and negativity (log-rank test p 0.12). Conclusions In this single center study, the presence of ANA had no significant predictive value in clinical features or outcomes in patients with ASS-ILD. Significance might be limited by our small sample. ANA negativity alone was not sufficient for excluding ASS-ILD. Further detailed investigation with myositis-specific and associated autoantibodies should be considered.
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