Background This article aims to analyze the clinical characteristics of myositis in Chinese patients with systemic lupus erythematosus (SLE).
Methods From January 2013 to April 2018, patients with myositis were included from the SLE database of Shanghai Ren Ji Hospital, South Campus. Myositis was diagnosed based on clinical symptoms, electromyography, magnetic resonance imaging, myositis antibody profile or muscle biopsy. Clinical and laboratory features at the diagnosis of myositis were collected. In this retrospective study, patients without myositis at the same time were selected as 1:1 by matching gender and age. Univariable and multivariable analysis were performed.
Results Of 1401 SLE patients, 21 (1.5%) had myositis. The mean follow-up of these patients was 3.3±3.3 years. Cardiac involvement was observed in three patients. 52.4% (n=11) patients had the data of myositis antibody profile, of which four patients were anti-Ku positive, two were anti-Ro-52 positive, one was anti-OJ positive, one was anti-Jo-1 and anti-OJ double positive, one was SAE1 weakly positive, and two were negative. All the patients received at least 1 mg/kg corticosteroids. The creatine kinase level of most patients (76.2%) fell back to normal within six months. One patient was refractory to many immunosuppressive agents including methotrexate, tacrolimus, rituximab and tocilizumab. Three patients died during follow-up. One of them deceased due to uncontrolled myositis with the involvement of myocardium and the other two died of invasive infections including septic shock and brain abscess.
Compared to matched SLE patients without myositis, they had more Raynauds phenomenon, interstitial lung diseases, and lupus nephritis, as well as lower creatinine level, lower disease activity and higher positive rate of anti-RNP (p<0.05). Upon multivariate logistic regression analysis, Raynauds phenomenon (OR 5.69 1.10~29.51) and lupus nephritis (OR 0.19, 0.37~0.99) were positively and negatively associated with myositis in SLE patients respectively.
Conclusions The prevalence of myositis was low in SLE patients in China. Myositis antibody profile is helpful for the differential diagnosis. Anti-Ku is the most common in these patients. Compared to patients without myositis, they were more likely to have raynauds phenomenon, but less likely to have kidney involvement.
Funding Source(s): None
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.