Background/Purpose: Antisynthetase Syndrome (AS) is a relatively rare autoimmune disease characterized by interstitial lung disease (ILD), myositis, inflammatory arthritis, Raynaud phenomenon, and mechanic’s hands. Eight autoantibodies (Ab) to aminoacyl-transfer-RNA synthetases have been described so far: Jo-1, PL-7, PL-12, EJ, OJ, YRS, KS, and Zo. The morbidity and mortality in AS is mainly related to the pulmonary complications. However, little has been reported about the prevalence of serositis (pleural and/or pericardial effusions) in AS other than small cohort studies (15-20 patients) and case reports. The purpose of our study was to determine the prevalence of serositis in AS, its clinical significance, and its association with specific AS Ab subtype(s).

Methods: Clinical data were obtained by retrospective review of electronic medical records from 2004 – 12/2017. AS required diagnosis by a rheumatologist, and patients had to have one of the following AS Ab: Jo-1, PL-7, PL-12, EJ, and OJ. Pleural effusions were qualified as trace, small, medium, or large, based on the findings on chest X-ray and thoracic CT scan. Pericardial effusions were classified as trace, small, medium, large, or tamponade, based on echocardiographic findings. Patients grouped by AS Ab type were compared using Pearson chi-square tests or Fisher exact tests.  Size measures were evaluated using Kruskal-Wallis tests that evaluate each measure as an ordered factor. For all measures, a P-value of < 0.05 was considered significant. 

Results:
A total of 93 patients were included in this study. The mean age was 57.5 years; 63% were female. The largest subset of patients had Jo-1 Ab (N=62). Pleural effusions were present in 44% of patients, 75% of which were bilateral. Out of 90 patients with complete data available, 42.2% had pleural effusion(s) and 47% had a pericardial effusion, 10% of which were moderate to large, and one patient had tamponade physiology. Jo-1 patients were significantly less likely to have pleural effusions when compared to patients with other Ab (P= 0.005). PL-12 had a higher frequency of pleural effusions relative to Jo-1 and PL-7, as well as, compared to all other Ab combined. No statistical comparisons were made between PL-7, EJ, and OJ Ab due to small sample sizes. Alternate causes of serositis were ruled out in all but two patients, who were found to have lung malignancy.

Conclusion:
Pleural and pericardial effusions were more common in patients with AS than previously thought. In this study, almost half of the patients had some degree of serositis. PL-12 had a higher frequency of pleural effusions than other AS Ab. Further research is necessary in this field.