Background/Purpose: Juvenile dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy in children. Approximately one-third of JDM patients attain drug-free remission (DFR) without relapse; however, there exist patients who are refractory to glucocorticoid therapy with or without immunomodulating agents. The purpose of this study was to examine the risk factors for achieving DFR in patients with JDM.
Patients and Methods: JDM patients referred to the Kagoshima University Hospital between 1994 and 2015 were enrolled. Demographic, clinical and laboratory data were retrospectively collected from medical records. DFR was defined as a condition that patients maintained symptom-free status with normal laboratory test for at least 1 year after withdrawal of all medications. The following parameters were evaluated as the related factors for achieving DFR in JDM patients: sex, age at onset, disease duration and clinical manifestations at starting therapy, laboratory data such as creatine kinase (CK) and aldolase (ALD), and initial treatment (intravenous methylprednisolone pulse therapy and/or methotrexate). Episodes of disease relapse and development of subcutaneous calcinosis during the disease course was also analyzed. Mann-Whitney U test and Chi-square test were used for comparison of continuous and categorical variables, respectively. Cumulative DFR rates were analyzed by Kaplan-Meier methods with log-rank test.
Results: A total of 40 JDM patients (18 male and 22 female patients) were involved. The mean age at onset was 6.2 ± 4.1 years, and the mean disease duration at starting the therapy was 0.6 ± 0.8 years. During the entire observation period, 22 patients had achieved sustained DFR (DFR group) while 18 patients were still on medication at the final visit (no-DFR group). Cumulative DFR rates of all patients were 21.6%, 35.6% and 58.6% at 3, 5 and 7 years after initiation of drug therapy, respectively. There were no significant differences between DFR group and no-DFR group with regard to sex, age at onset, disease duration by starting initial therapy, the presence or absence of skin ulcer and interstitial pneumonia. As to laboratory tests, the maximum serum levels of ALD (ALDmax) were significantly higher in no-DFR group than that in DFR group (p=0.0202), though the serum CKmax showed no difference between the two groups. In addition, Kaplan-Meyer analysis revealed that the cumulative DFR rates were significantly lower in patients with ALDmax ≥20 IU/L (p=0.0079, Figure 1) and patients with relapse (p<0.0001) or subcutaneous calcinosis (p=0.0035) during the disease course.
Conclusion: ALDmax ≥20IU/L at starting therapy, and presence of episodes of relapse or subcutaneous calcinosis during the disease course may be predictors for a refractory disease course in JDM. Therefore, more prolonged and/or more aggressive therapies are needed to attain DFR in these patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-factors-for-achieving-a-drug-free-remission-in-patients-with-juvenile-dermatomyositis/