Résumé :
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Anti-synthetase syndrome is characterized by myositis, interstitial lung disease (ILD), arthritis, Raynaud’s phenomenon, skin change of the hands (mechanic’s hand), and the presence of autoantibodies of which anti-histidyl-transfer RNA synthetase (anti-Jo-1) is the most frequent. The aim of this retrospective study was to analyse the characteristics and outcome of 52 anti-Jo-1+ patients according to their clinical presentation and treatments. We describe 52 patients (13M/39F, median age: 41 y. [IQR, 32-53]). At diagnosis, 75% presented a proximal weakness (severe in 44%), 65% myalgia, 78% dyspnoea (> III or IV NYHA in 36%), 73% arthralgia (6% arthritis), 44% Raynaud’s phenomenon (severe in 8%) and 17% mechanic’s hands. Other signs were fever in 31% (> 38.5°C in 8%), weight loss in 11%, sicca syndrome in 35%. Their median CK level was 3575 U/ml [1188-8828] and CRP 19 mg/ml [6-58]. ANA titers were normal (< 1/80) in 45% or elevated ? 1/320 in 30%. The most frequently associated ENA was anti-SSA (Ro52 and/or Ro60) in 62%. CT scan showed ILD in 77%. Pulmonary function tests showed median total lung volume (TLV): 64.5% [55-86], slow vital capacity (SVC): 68.5% [55-83], and CO diffusion capacity (CODC): 48% [39-58]. All treated patients (49/52) received prednisone (1 mg/kg/day) during 4.5 y. [1.8-7.0], 9 in single therapy. For the 40 others, association with immunosuppressive drugs was needed. Overall, 21 treated patients were not ameliorated or worsened (3 deceased from their ILD), and 28 improved or recovered. Neither sex, age at onset, ANA titers, associated ENA, CK level, treatments nor their duration was associated with improvement under therapy. Patients who worsened presented higher value of CRP (p=0.003) and lower value of most pulmonary markers (TLV p=0.004, SVC p=0.015, CODC p=0.005). This study outlines the burden of chest involvement appreciated by pulmonary functional test for the prognosis of anti-synthetase syndrome.
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