Background/Purpose: Anti-aminoacyl-tRNA synthetase antibodies (Abs), which mainly consists of anti-Jo1, PL-7, PL-12, EJ, OJ and KS, are the most common myositis-specific autoantibodies (MSAs). It has been recognized that anti-synthetase Abs are associated with characteristic clinical phenotype, chronic disease course, good response to initial glucocorticoid therapy and relatively good prognosis. However, we sometimes encounter such patients that are resistant to immunosuppressive therapies and have poor prognosis. Therefore, we retrospectively analyzed prognostic factors in polymyositis(PM)/ dermatomyositis (DM) patients with anti-synthetase Abs.

Methods: We retrospectively examined medical records of 121 PM/DM patients with anti-synthetase Abs who had been treated in our hospital from April 2001 to December 2016 (32 with Jo-1, 26 with PL-7, 25 with EJ, 21 with PL-12, 11 with OJ, 4 with KS, 1 with PL7 and PL12, 1 with Jo-1 and PL12). Anti-ARS Abs were examined with RNA immunoprecipitation using Hela cells. We analyzed the prognostic factors with univariate cox proportional hazards regression analysis. Next, we analyzed each of them with multivariate analysis. Comparison of survival time among each anti-synthetase Abs, we used Kaplan-Meier method.

Results: The 10-year survival of whole anti-synthetase Abs-positive PM/DM patients was 74.7%. 21 patients died of interstitial pneumonia (n=8), infection (n=2), malignancy (n=4), thrombotic thrombocytopenic purpura (TTP) (n=1), alveolar hemorrhage (n=2), subarachnoid hemorrhage (n=1), unknown cause (n=3). In univariate analysis, old age at onset , male , anti-PL-7 ,high values of lactate dehydrogenase, high dose of maintenance glucocorticoid, no use of immunosuppressant were found to be significant poor prognostic factors. Multivariate analysis revealed 5 significant poor prognostic factor, anti-PL-7 Ab, old age at onset , male , high dose of maintenance glucocorticoid , no use of immunosuppressant. In Kaplan-Meier analysis, it was suggested that anti-EJ-positive patients may have poor prognosis after more than 15 years follow-up as well as anti-PL-7-positive patients.

Conclusion: The poor prognostic factors in anti-ARS-positive patients were anti-PL-7 Ab, old age at onset , male , high dose of maintenance glucocorticoid , no use of immunosuppressant. Moreover, anti-EJ have poorest survival after more than 15 years follow-up as well as anti-PL-7.