Clinical characterisation of a multicentre nationwide cohort of patients with antisynthetase syndrome

Background: Antisynthetase syndrome (ASyS) is characterised by the association of inflammatory myopathy, interstitial lung disease (ILD), arthritis, Raynaud's phenomenon (RP) or mechanic's hands (MH), with the presence of anti-aminoacyl-tRNA-synthetase antibodies (anti-ARS). It has been suggested that different anti-ARS may be associated with distinct clinical pictures. Objective: To characterise the clinical and immunological features of a multicentric nationwide cohort of ASyS patients. Methods: This is a multicentre retrospective cohort study including patients with ASyS from nine Portuguese rheumatology centres. Data on patients' demographics, signs and symptoms, laboratory results, pulmonary imaging findings and treatment with immunomodulators were collected. Comparison between patients with different anti-ARS antibodies was made using the Chi-square test for categorical variables and Student's t-test or Man-Whitney test for continuous variables, considering anti-Jo1 positive patients as the reference group. Results: Seventy patients were included (70% female) with a median age in years at disease onset of 52 (15-75) years and median follow-up time of 3 years (range 0-32). The three most common clinical manifestations were ILD (n=53, 75.7%), followed by arthritis (n=43, 61.4%) and myositis (n=37, 52.9%). Forty-three patients were positive for anti-Jo1 (61.4%), 11 for anti-PL12 (15.7%), 10 for anti-PL7 (14.3%), 4 for anti-EJ (5.7%), and 2 for anti-OJ (2.9%) antibodies. Antibody co-positivity with anti-Ro52 antibodies was found in 15 patients (21.4%) and was more prevalent in anti-Jo1 patients. ILD prevalence was similar in the different anti-ARS subgroups, without statistically significant differences. Patients positive for anti-PL7 antibodies had significantly lower risk of presenting arthritis (p =< 0.05) and those positive for anti-PL-12 antibodies had a significantly lower risk of presenting myositis than the reference group of anti-Jo1 positive patients (p =< 0.05). RP was more frequently found in patients positive for anti-PL-12 than in anti-Jo1-positive patients (p =< 0.05). Malignancies were reported in four (5.7%) patients, none of whom were anti-Ro52-positive, and one of such patients had a double malignancy. Only three deaths were reported. Corticosteroids were the most frequently prescribed therapy and the use of immunosuppressive drugs was decided according to the type of predominant clinical manifestation. Conclusion: The three most common clinical manifestations were ILD, followed by arthritis and myositis. Patients positive for anti-PL7 antibodies had significantly lower risk of presenting arthritis and those positive for anti-PL-12 antibodies had a significantly lower risk of presenting myositis than the reference group of anti-Jo1 positive patients. RP was more frequently found in patients positive for anti-PL-12 than in anti-Jo1-positive patients. Corticosteroids were the most frequently prescribed therapy. These results are generally concordant with data retrieved from international cohorts.