Myositis-specific antibodies and clinical characteristics in patients with autoimmune inflammatory myopathies: reported by the Argentine Registry of Inflammatory Myopathies of the Argentine Society of Rheumatology.

INTRODUCTION/OBJECTIVES: To describe clinical features in patients with inflammatory myopathies (IMs) from the Argentine Registry of Inflammatory Myopathies, and their relationship with myositis-specific antibodies (MSAs). METHODS: This cross-sectional study included 360 adult patients with dermatomyositis (DM), polymyositis (PM), and inclusion body myositis. Demographics, clinical, and serological characteristics were retrospectively recorded (2016-2019). MSAs were determined by immunoblotting. Patients who were positive for anti-Jo-1, Mi-2, and MDA5 were compared against a group of patients, taken as reference group, who were negative for all MSAs. RESULTS: Women 72%, median age at diagnosis was 47.3 years (18-82). The most frequent subtypes were DM (43.9%) followed by PM (30%).The most frequent MSAs were anti-Jo-1 (51/317), 16.1%; MDA5 (12/111), 10.8%, and Mi-2 (23/226), 10.2%. Anti-Jo-1 was associated (p < 0.05) with a higher frequency of chronic disease course, interstitial lung disease (ILD), arthritis, and mechanic's hands. Anti-Mi-2 was found in patients who had higher frequency of skin manifestations and higher CK values (p < 0.001). Patients with anti-MDA5 had normal or low CK levels. Anti-MDA5 was associated (p < 0.05) with skin manifestations, arthritis, and ILD. The rest of MSAs had frequencies lower than 8%. Anti-TIF1ϒ was found in eight DM patients and one had cancer. Anti-SRP was found in seven patients who had PM and elevated CK. CONCLUSION: Anti-Jo-1 was the most frequent MSA, and was associated with ILD; MDA5 was associated with CADM and ILD, and Mi-2, with classical DM. Despite the different prevalence with respect to other cohorts, the clinical characteristics for each MSA group were similar to the data reported in other studies. Key Points • This study describes the prevalence of MSAs in the Argentine Registry of IMs. • Anti-Jo-1 and anti-MDA5 were associated with ILD. • Anti-Mi-2 was the third most frequent MSA, associated with classical DM.

Validation of the adjusted global antiphospholipid syndrome score in systemic lupus erythematosus patients in Argentina.

INTRODUCTION: Assessment of risk both for pregnancy morbidity and thrombosis in the presence of anti-phospholipid antibodies (aPL) is still a challenge in Systemic Lupus Erythematosus (SLE) patients. The Global Antiphospholipid Syndrome Score (GAPSS) takes into account the aPL profile (criteria and non-criteria aPL), the conventional cardiovascular risk factors and the autoimmune antibody profile. An adjusted model of the score (aGAPSS) excluding anti-phosphatidylserine/Prothrombin (aPS/PT), suggests that the score is able to stratify patients for their rate of events making it widely applicable in daily clinical practice. OBJECTIVE: To validate the aGAPSS in a multicentric cohort of SLE patients in Argentina. PATIENTS AND METHODS: consecutive SLE patients with and with andwithout thrombotic events from seven Rheumatologist centers were included. Traditional cardiovascular risk factors, aPL antibodies and medications received (aspirin, hydroxychloroquine and anticoagulation) were collected. The score aGAPSS was calculated for each patient at the last visit by adding together the points corresponding to the risk factors: 1 for hypertension, 3 for dyslipidemia, 4 for LA and B2GPI (IgM or IgG) antibodies and 5 for aCL (IgM or IgG) antibodies. The discriminative ability of the aGAPSS was calculated by measuring the area under the receiver operating characteristic curve (AUC). Multivariate logistic regression analysis was performed to examine the impact of multiple cardiovascular risk factors and laboratory parameters on the occurrence of thrombosis. RESULTS: Two hundred and ninety-six SLE patients were included. One-hundred and twenty-one patients (40.9%) presented thrombotic and/or pregnancy complications. Median aGAPSS was significantly higher in patients who experienced an event (thrombosis and/or pregnancy morbidity) compared with those without [4 (IQR 1-9) versus 1 (IQR 0-5); p < 0.001]. The best cut off point for the diagnosis of thrombosis and/or pregnancy complications was aGAPSS ≥4. Multivariate logistic regression analysis showed that aCL antibodies [OR 2.1 (95% CI 1.16-3.90); p = 0.015] were an independent risk factors for thrombotic events. CONCLUSIONS: This score is a simple tool, easy to apply to SLE patients in daily practice. The use of the aGAPSS could change the non-pharmacologic and pharmacologic treatment in higher risk patients to improve their survival.