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Objective: Macrophage activation syndrome (MAS), a life-threatening inflammatory complication, is increasingly recognized in childhood-onset systemic lupus erythematosus (cSLE). It can be a challenge to differentiate active cSLE from MAS. We generated decision rules for discriminating MAS from active cSLE in newly diagnosed patients.Methods: We conducted a retrospective cohort study of consecutive, newly diagnosed, active cSLE patients with fever, requiring hospital admission to The Hospital for Sick Children from January 2003 to December 2007 (cohort 1) and January 2008 to December 2013 (cohort 2). All patients met ≥ 4 American College of Rheumatology or Systemic Lupus International Collaborating Clinics criteria, and were steroid-naïve and infection-free. MAS was diagnosed based on expert opinion. Recursive partitioning was applied to each cohort to derive a decision rule based on clinical and laboratory features, distinguishing MAS from non-MAS cSLE. Each decision rule was applied to the alternate, independent cohort. Sensitivity and specificity of these decision rules were compared to existing criteria.Results: Cohort 1 (n = 34) and cohort 2 (n = 41) each had 10 patients with MAS. Recursive partitioning in cohort 1 identified ferritin ≥ 699 μg/L as the sole best discriminator between MAS and non-MAS patients (R2 = 0.48), and in cohort 2, ferritin ≥ 1107 μg/L was the best discriminator for MAS, followed by lymphocytes < 0.72 × 103/mm3 (R2 = 0.52). Cross-validation of our decision rules maintained 90-100% sensitivity and 65-85% specificity.Conclusion: Our decision rule demonstrated improved performance compared to preliminary guidelines for MAS in cSLE from the Lupus Working Group of the Paediatric Rheumatology European Society and familial hemophagocytic lymphohistiocytosis diagnostic criteria. Validation in independent cohorts is required. [ABSTRACT FROM AUTHOR]

Objective: Currently there are 2 different classification criteria for systemic lupus erythematosus (SLE): American College of Rheumatology (ACR) and Systemic Lupus International Collaborating Clinics (SLICC). The aim of this study was to compare the sensitivities of ACR and SLICC criteria in childhood-onset SLE (cSLE) using a large, multiethnic cohort.Methods: We conducted a retrospective study of 722 patients diagnosed with cSLE at The Hospital for Sick Children (SickKids). Prospectively collected data from SickKids' Lupus Database were reviewed/validated against medical records prior to ACR and SLICC scoring based on cumulative symptoms up to the last visit. Sensitivities were compared using McNemar's test. Descriptive statistics were used to identify SLE features unique to each set of criteria and autoantibodies not included in either.Results: ACR and SLICC sensitivities were as follows: 92.4% and 96.3% overall (p = 0.001); 82.5% and 91.3% (p = 0.01) in those scored ≤ 1 year from diagnosis; 92.7% and 97.9% (p = 0.02) in those scored 2-3 years from diagnosis. Forty-eight of 55 (87.3%) patients who did not meet ACR criteria met SLICC criteria through SLICC-specific criterion or renal biopsy. Twenty of 27 (74.1%) patients who did not meet SLICC criteria met ACR criteria as a result of photosensitivity (73.9%) and ACR lymphopenia criteria (26.1%). Six of 7 patients (85.7%) who were clinically diagnosed with cSLE but did not meet either SLICC or ACR criteria had anti-Ro antibodies.Conclusion: SLICC criteria were significantly more sensitive than ACR criteria in cSLE classification, especially early in the disease course. Because of the extreme rarity of primary Sjögren syndrome in children, one may consider adding anti-Ro antibodies to the classification criteria for cSLE because they are present in ∼40% of patents with cSLE. [ABSTRACT FROM AUTHOR]

Electrocardiograms taken at rest of 2 children with transplacental exposure to anti-Ro antibody but 1:1 atrioventricular conduction demonstrated sinus node disease. Treadmill exercise testing of 28 patients with congenital complete heart block found 3 patients with chronotropic incompetence of the sinus node. [ABSTRACT FROM AUTHOR]

Objective: Systemic lupus erythematosus (SLE) is the prototypical systemic autoimmune disorder, with complex etiology and a strong genetic component. Recently, gene products involved in the interferon pathway have been under intense investigation in terms of the pathogenesis of SLE. STAT-1 and STAT-4 are transcription factors that play key roles in the interferon and Th1 signaling pathways, making them attractive candidates for involvement in SLE susceptibility., Methods: Fifty-six single-nucleotide polymorphisms (SNPs) across STAT1 and STAT4 on chromosome 2 were genotyped using the Illumina platform, as part of an extensive association study in a large collection of 9,923 lupus patients and control subjects from different racial groups. DNA samples were obtained from the peripheral blood of patients with SLE and control subjects. Principal components analyses and population-based case-control association analyses were performed, and the P values, false discovery rate q values, and odds ratios with 95% confidence intervals were calculated., Results: We observed strong genetic associations with SLE and multiple SNPs located within STAT4 in different ethnic groups (Fisher's combined P = 7.02 x 10(-25)). In addition to strongly confirming the previously reported association in the third intronic region of this gene, we identified additional haplotypic association across STAT4 and, in particular, a common risk haplotype that is found in multiple racial groups. In contrast, only a relatively weak suggestive association was observed with STAT1, probably due to its proximity to STAT4., Conclusion: Our findings indicate that STAT4 is likely to be a crucial component in SLE pathogenesis in multiple racial groups. Knowledge of the functional effects of this association, when they are revealed, might improve our understanding of the disease and provide new therapeutic targets.