Background Patients with polymyositis (PM) and dermatomyositis (DM) often have repeated exacerbations of myositis. Sometimes immunosuppressive agents are added to induce remission in steroid-resistant cases, with steroid reduction in maintenance therapy, and to prevent exacerbations. However, comparative clinical studies are difficult to conduct and the appropriate immunosuppressive agents are not known [1–2]. There are also no studies of the treatment in recurrent cases with repeated relapses.
Objectives In this study, we defined myositis that relapses more than once as recurrent myositis and examined its risk factors and re-induction treatments.
Methods Patients from our PM and DM database who were hospitalised between January 1991 and September 2016 were reviewed. We included only patients who had been followed for more than 1 year.
Results There were 14 cases (13.1%) with recurrent myositis. The average observation period was 11.3 and 8.0 years in the relapsing and non-relapsing groups, respectively (P =0.18), and the average ages at onset were 46.2 and 55.0 years (P =0.17). The myositis relapse rate was significantly higher in the anti-aminoacyl-tRNA synthetase (ARS) antibody-positive group than in the group with other antibodies [8/24 (33.3%) vs. 0/14 (0.0%) cases; P =0.02]. The myositis relapse rate was significantly lower in the group in which one more immunosuppressive agent was combined in the initial treatment than in the group without any [3/53 (5.7%) vs. 11/48 (22.9%) cases; P =0.02]. The myositis relapse rate did not differ significantly between DM and PM, men and women, the groups with or without malignancy, the groups with or without interstitial pneumonia (IP), and groups with or without the following initial findings: fever, joint pain, dysphagia, constipation, bedridden, muscle pain, distal muscle weakness, cutaneous symptoms (e.g., heliotrope rash, Gottron's sign, V signs, Raynaud's phenomenon, skin ulcers and necrosis, and itching sensation), cardiac complications, hypertension, diabetes, and smoking history. There was no significant difference in the serum creatine kinase and C-reactive protein between the relapse and no-relapse groups. Only 3 of 14 cases (21.4%) had successful re-remission induced and were on maintenance therapy. In two of these cases, two immunosuppressive agents other than glucocorticoid were added: tacrolimus and methotrexate in one and tacrolimus and mycophenolate mofetil in the other. The other 11 patients were treatment-resistant.
Conclusions The presence of anti-ARS-antibody and initial treatment with glucocorticoid only (without any other immunosuppressive agent) were the only two risk factors for recurrent myositis; none of the other factors examined were significant. Recurrent myositis is often treatment-resistant; if one immunosuppressive agent cannot introduce remission, it is worth trying two agents.
Gordon PA, et al: Immunosuppressant of relapses and immunomodulatory treatment for dermatomyositis and polymyositis. Cochrane Database Syst Rev 2012; 15(8):CD003643.
Dalakas MC, et al: A controlled trial of high-dose intravenous immune globulin infusions as treatment for dermatomyositis. N Engl J Med. 1993 Dec 30;329(27):1993–2000.
Disclosure of Interest None declared