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SAT0318 Antisynthetase Syndrome: Clinical and Serological Characteristics at Disease Onset

Background Antisynthetase syndrome (ASS) is a rare condition characterized by the presence of one or more of the following clinical features: arthritis, Raynaud's phenomenon, “mechanic's hands”, interstitial lung disease and polymyositis, in patients with antisynthetase antibodies which target aminoacyl-tRNA synthetases enzymes, being Anti-Jo1 the most common one. Objectives To investigate the clinical features of ASS at disease onset and their influence on the disease clinical course. Methods 32 consecutive patients diagnose with ASS, were prospectively enrolled between 1988 and 2013. Inclusion criteria consisted of having a positive test for antisynthetase antibodies, regardless of fulfilling classification criteria for other rheumatic diseases. Serological, clinical and demographic features were registered both at clinical onset and during the course of the disease. Anti-synthetase antibodies were determined by LIA or ELISA. Results From 32 patients, 21 (65.6%) were females and 11 (34.4%) were males. Mean age at clinical onset was 47.4 years (SD 18.8) and the mean time of disease course was 11.1 years (SD 10.2). The most common feature at disease onset was arthritis in 50% of the patients (8 of them presenting arthritis>6 weeks), followed by constitutional syndrome (31.3%) and muscular symptoms (25%). Table 1 shows the different clinical features and frequency of occurrence at onset. During the course of disease 28 patients (87.5%) developed musculoskeletal manifestations, 26 (81.3%) arthritis, 21 (65.6%) cutaneous manifestations, 20 (62.5%) interstitial lung disease and 13 (40.6%) Raynaud's phenomenon. Associations between the presence of Anti-Ro52 and arthritis at disease onset (p=0.009), interstitial lung disease (p=0.002) and low complement levels (p≤0.001) were found. Table 1. Antisynthetase syndrome: clinical features and frequency of occurrence at onset (n=32) Frequency (n) Percentage (%) Fever >37.5°C 7 21.9 Constitutional syndrome 10 31.3 Arthritis 16 50.0 Arthritis >6 weeks 8 25.0 Cutaneous manifestations 7 21.9 Pulmonary manifestations 5 15.6 Cardiologic manifestations 1 3.1 Raynaud's phenomenon 5 15.6 Musculoskeletal manifestations 8 25.0 Sjögren's Syndrome 1 3.1 Conclusions In our study, clinical features at onset were very heterogeneous. Patients showed neither all clinical features at the same time nor during the disease course. In our cohort, Anti-Ro52 antibody was associated to both the presence of arthritis at onset and the development of interstitial lung disease, which could be relevant for differential diagnosis and prognosis. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.3113