P.P.T.1, J.Z.LOW1, C.C.G.2, M.M.1
Tan Tock Seng Hospital1, Department of Rheumatology, Allergy and Immunology2
Antisynthetase syndrome (ASS) is associated with the anti-Jo1 antibody (anti-Jo 1 Ab). Interstitial lung disease (ILD) is a major organ manifestation and the leading cause of mortality. Our aim was to determine clinical profile and outcomes of anti-Jo 1 Ab positive patients diagnosed with ASS-ILD in Singapore.
A review of 105 patients with positive myositis specific antibodies between January 2015 and July 2019 was undertaken. Demographic data, clinical manifestations, types of ILD, immunosuppressive treatment regimen and improvement in pulmonary function and creatine kinase (CK) levels were recorded.
31 patients out of 105 were positive for aminoacyl-tRNA synthetase Abs. 14 were positive for anti-Jo 1 Ab. 85.7% of the 14 anti-Jo 1 positive patients had concomitant anti-Ro52 antibodies. Clinical features included myositis, polyarthritis, rash and mechanics hands, all patients had ILD and the most common HRCT pattern was non-specific interstitial pneumonia.
All patients received glucocorticoids. 71.4% received azathioprine, 50% cyclophosphamide, and 35.6% mycophenolate mofetil. 42% had received hydroxychloroquine, 21.4% methotrexate, 14.3% cyclosporin, 7.1% leflunomide and 7.1% rituximab. Median CK at diagnosis was 1834 U/L with improvement to 191 and 71 U/L at 6 and 12 months, respectively. Median improvement of FVC and DLCO within 6 to 12 months was 13% and 6.5% and following 12 months of treatment, 10% and 18% respectively.
Treatment was effective in reducing CK levels and improving FVC and DLCO within 1 year. All patients required glucocorticoids whilst azathioprine, cyclophosphamide, and mycophenolate mofetil were the most commonly used 2nd line agents.