Alpha Omega Alpha Honor Medical Society

2010 Research Abstract

Prevalence of Inflammatory Myositis in Patients with Pediatric Systemic Lupus Erythematosus in Alabama

Investigator: Jessica Record, University of Alabama School of Medicine
Mentor: Randy Q. Cron, MD, PhD, University of Alabama at Birmingham

Background: Inflammatory myositis has traditionally been recognized as a feature in 5-11% of adult systemic lupus erythematosus (SLE) patients. The aims of this study were to determine the prevalence of myositis in a cohort of pediatric SLE patients from a single center in the state of Alabama, to compare this rate with the reported prevalence in the medical literature, and to evaluate clinical factors for possible association with myositis.

Methods: We performed a retrospective chart review of 55 patients who satisfied ≥4 out of 11 ACR criteria for SLE who were evaluated by the Division of Pediatric Rheumatology at the Children's Hospital Alabama since January 1, 2008. Laboratory, clinical, and serologic characteristics of all patients were collected. Patients were defined as having myositis if they satisfied one of the following categories: 1) Proximal muscle weakness on physical exam with evidence of lower extremity muscle edema on MRI; 2) Proximal muscle weakness on physical exam with an elevation in one of the following muscle enzymes: CK, AST, aldolase, or LDH; or 3) Patient reported muscle weakness or muscle pain (without weakness noted on physical exam) and had an elevated CK. The rate of myositis in this cohort was compared to previously reported rates using the chi-square test. Fisher's exact test and one-way ANOVA were used to determine possible associations between myositis and clinical and laboratory findings.

Results: Inflammatory myositis was present as a feature of SLE in 31% (n=17) with a 95% confidence interval of 19-45%, statistically different from the reported rates of 5-11% (p<0.0001). Positive associations with myositis were the presence of anti- ribonucleoprotein antibodies (p=0.009) and anti-Smith antibodies (p=0.06). Negative associations with myositis were the presence of anti-double stranded DNA antibodies (p=0.02) and hematologic disorders (p=0.02).

Conclusions: In the state of Alabama, pediatric SLE myositis is present at a statistically higher rate than previously published values of adult SLE myositis. The association of both anti-ribonucleoprotein and anti-Smith antibodies with myositis further highlights the significant overlap SLE has with other autoimmune diseases such as mixed-connective tissue disease and the challenges that come with appropriately classifying and treating these overlap patients.

Updated on January 6, 2011.

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