Hierarchical cluster and survival analyses of antisynthetase syndrome: phenotype and outcome are correlated with anti-tRNA synthetase antibody specificity

The clinical phenotype and evolution of antisynthetase syndrome (ASS) are heterogeneous. This study was therefore undertaken to identify subgroups of ASS patients with similar clinico-biological features and outcomes. This retrospective multicentric study included 233 consecutive patients with three different anti-aminoacyl-tRNA-synthetase antibodies (anti-ARS): anti-Jo1 (n=160), anti-PL7 (n=25) and anti-PL12 (n=48). To characterise ASS patients, bivariate, multiple correspondence (MCA), cluster and survival analyses were performed. Interstitial lung disease (ILD) and myositis were the most common ASS manifestations. However, their respective frequencies were correlated to anti-ARS specificity: ILD was more frequent (80% and 88% vs 67%, p=0.014) whereas myositis was less common (44% and 47% vs 74%, p<0.001) in patients with anti-PL7 and anti-PL12 compared to anti-Jo1. The MCA suggested that anti-PL7 and anti-PL12 phenotypes were close to one another and distinct from anti-Jo1. The clustering analysis confirmed these data, identifying subgroups strongly defined by the anti-ARS specificity and other clinical features. Cluster 1 (n=175, 86% of anti-Jo1) defined patients with the most diffuse phenotype, whereas patients from cluster 2 (n=48, 96% of anti-PL12 and anti-PL7) exhibited a disease more restricted to the lung. Patient survival was also conditioned by the anti-ARS specificity, and was significantly lower in patients with anti-PL7/12 rather than anti-Jo1 (p=0.012). Other factors associated with poor survival were mostly related to pulmonary involvement, including severe dyspnea (p=0.003) and isolated ILD (p=0.009) at diagnosis. In patients with ASS, the phenotype and the survival were correlated with the anti-ARS specificity.