The clinical phenotype associated with myositis-specific and associated autoantibodies: A meta-analysis revisiting the so-called antisynthetase syndrome

To describe the clinical spectrum associated with aminoacyl-transfer RNA synthetase (ARS) autoantibodies in patients with idiopathic inflammatory myositis defined according to Peter and Bohan's criteria.Cohort studies were selected from MEDLINE and Embase up to August 2013. Two investigators independently extracted data on study design, patient characteristics, and clinical features (interstitial lung disease [ILD], fever, mechanic's hands [MH], Raynaud's phenomenon [RPh], arthralgia, sclerodactyly, cancer and dermatomyositis-specific rash) according to the presence of myositis-specific (anti-aminoacyl-transfer RNA synthetase [ARS], anti-signal recognition particle [anti-SRP] and anti-Mi2) and myositis-associated (anti-PM/Scl, anti-U1-RNP and anti-Ku) autoantibodies.27 studies (3487 patients) were included in the meta-analysis. Arthralgia (75%, CI 67-81) and ILD (69%, CI 63-74) were the most prevalent clinical signs associated with anti-ARS autoantibodies. Anti-Mi2 and anti-SRP autoantibodies were associated with few extramuscular signs. ARS autoantibodies were identified in 13% of patients with cancer-associated myositis (5-25). Patients with non-anti-Jo1 ARS had greater odds of presenting fever (RR 0.63, CI 0.52-0.90) and ILD (RR 0.87, CI 0.81-0.93) compared to those with anti-Jo1 autoantibodies. The frequencies of myositis (RR 1.60, CI 1.38-1.85), arthralgia (RR 1.52, CI 1.32-1.76) and MH (RR 1.47, CI 1.11-1.94) were almost 50% higher in patients with anti-Jo1 compared to non-anti-Jo1 ARS autoantibodies. Patients with anti-PM/Scl differed from those with anti-ARS autoantibodies by a greater prevalence of RPh (RR 0.70, CI 0.53-0.94) and sclerodactyly (RR 0.47, CI 0.25-0.89). ILD was less frequent in patients with anti-U1-RNP autoantibodies (RR 3.35, CI 1.07-10.43). No difference was observed between anti-ARS and myositis-associated autoantibodies for other outcomes.The presence of anti-ARS autoantibodies delimits a heterogeneous subset of patients with a high prevalence of myositis, MH, arthralgia in anti-Jo1 patients, and RPh and fever in non-anti-Jo1 patients. The clinical signs of populations positive for anti-PM/Scl and anti-ARS autoantibodies largely overlap, especially with regard to ILD, challenging the clinical delimitation of the antisynthetase syndrome.