Clinical Characteristics and Poor Predictors of Anti-NXP2 Antibody-Associated Chinese JDM Children

Abstract

Background. Juvenile dermatomyositis (JDM) is a rare and sometimes fatal disease in children. The subtype of anti-NXP2 antibody-associated JDM is the leading cause of death in JDM, but there are no reports about clinical characteristics and high risk factors of poor prognosis. For the first time, we introduced the clinical characteristics and poor predictors of anti-NXP2 antibody-associated juvenile dermatomyositis in Chinese children.Methods. Twenty-six patients with anti-NXP2 antibody-related JDM from 85 JDM patients diagnosed from January 2016 to November 2019 were involved. Logistic regression was used to analyze the risk factors for refractory cases and death.Results. The ratio of male to female was 9:17. The median age of onset was 4.5 (1–13) years. Twenty-four cases (92.3%) had rash and muscle weakness. Treatments included glucocorticoids, immunosuppressive agents, biological agents (7 cases), plasma exchange, Janus kinase inhibitor (7 cases) and autologous stem cell transplant (1 case). Eleven cases (11/26, 42.3%) were refractory JDM associated with edema, skin ulcer, muscle strength < = grade 3, CD4/CD8 ratio < 1.4 and SF > 200ug/ml. Among 6 cases (6/26, 23.1%) with severe gastrointestinal involvement, 5 cases died and 1 case survived after ASCT. The risk factors for gastrointestinal involvement and death were edema, skin ulcer, severe muscle weakness (Dysphagia/Hoarseness/Lower voice), BMI < 15 and ANA positive.Conclusions. Anti-NXP2 antibody-positive JDM of Chinese children was characterized by rash and severe muscle weakness. Edema, skin ulcer and severe muscle weakness predicted refractory and poor prognosis. Decreased CD4/CD8 ratio and high SF related with refractory cases, and very low BMI and ANA (+) predicted high risk of gastrointestinal involvement and death.

The Significance of Autoantibodies in Juvenile Dermatomyositis

“…It was observed that low body mass index (BMI) and positive ANA were associated with gastrointestinal involvement and mortality in this group of patients [24]. In research performed by Wang et al, a lowered CD4/CD8 ratio (p = 0:0255) and high ferritin level (p = 0:0361) appeared to correlate with more refractory cases [3]. Furthermore, serum ferritin was shown to be valuable as a predictor of the occurrence of concomitant ILD [25].…”

“…In adults, elevated serum levels of muscle enzymes, including creatine kinase (CK), transaminases, lactate dehydrogenase (LDH), and aldolase, play an important role in the diagnosis and severity assessment of DM. Nonetheless, those enzymes proved to be weakly correlated with disease severity in JDM [3][4][5]. The clinical outcome of JDM may vary depending on several comorbidities, such as interstitial lung disease or calcification.…”

Use of Janus kinase inhibitors in dermatomyositis: a systematic literature review

“…12 weeks of treatment with a JAK inhibitor (45); in patients with longerterm use, scores improved by 7-39 points (45,46). With long-term JAK inhibitor use (12-31 months), CMAS scores improved by 18-41 points from baseline (54).…”

“…Overall, improvement with JAK inhibitor treatment was reported in 30 patients (83%). Pre-and posttreatment muscle activity scores (MMT-8, Mus-cle DAS, or CMAS) were available for 25 patients with muscle disease (45)(46)(47)(48)(50)(51)(52)(53)(54). Of these 25 patients, seven (28%) did not show objective improvements in muscle disease with JAK inhibitor therapy.…”

“…Of the patients with muscle disease who had objective muscle activity responses to JAK inhibitor treatment, baseline MMT-8 ranged from 108-142 (45,46), and baseline CMAS ranged from 0-46 (47)(48)(49)(50)(51)(52)54). MMT-8 scores improved by 25-26 points from baseline after Use of JAK inhibitors in dermatomyositis / J.J. Paik et al…”