Clinical characteristics and diagnostic indicators of childhood-onset systemic lupus erythematosus complicated with macrophage activation syndrome.

objectiveAnalyze the clinical and laboratory characteristics of childhood-onset systemic lupus erythematosus (cSLE) complicated by macrophage activation syndrome (MAS), evaluate the applicability of the 2016 European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organisation classification criteria for sJIA-associated MAS (referred to as the 2016 sJIA-MAS classification criteria) in the context of different autoimmune diseases (cSLE-MAS), and propose new diagnostic predictive indicators to provide references for improving the early identification and diagnosis of patients with cSLE-MAS.

methodsThe clinical laboratory data of 32 children with cSLE-MAS admitted to the Department of Nephrology and Immunology in Children's Hospital of Hebei Province from May 2015 to January 2025 were retrospectively analyzed. This data was compared with that of 32 children with cSLE, who had the same gender ratio and presented with fever but without MAS. Laboratory indicator cut-off values for cSLE combined with MAS were predicted from receiver operating characteristic (ROC) curves.

resultsCompared with cSLE, cSLE-MAS exhibited higher rates of lymphadenopathy, liver dysfunction, and hematologic abnormalities; higher levels of serum ferritin, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, hydroxybutyrate dehydrogenase, and triglycerides; lower levels of white blood cells, absolute neutrophil count, and fibrinogen; and longer durations of fever and hospitalization. The use of high-dose methylprednisolone sodium succinate pulse therapy and immunoglobulin was more frequent. All differences were statistically significant (P < 0.05). ROC curve analysis revealed that the following cutoff values provided optimal diagnostic differentiation for cSLE-MAS: ferritin ≥ 621.6 µg/L, aspartate aminotransferase ≥ 75.5 U/L, fibrinogen ≤ 1.96 g/L, triglycerides ≥ 2.31 mmol/L, and lactate dehydrogenase ≥ 382 U/L. The 2016 sJIA-MAS classification criteria demonstrated both sensitivity and specificity of 90.6% in the diagnosis of cSLE-MAS. The sensitivity and specificity were improved to 93.8% and 96.9%, respectively, after modifications involving ferritin, aspartate aminotransferase, triglycerides, and fibrinogen, with the removal of platelets and the addition of lactate dehydrogenase.

conclusionDifferent autoimmune diseases complicated by MAS exhibit variations in laboratory indicators due to the distinct characteristics of the underlying diseases. Applying uniform diagnostic criteria for MAS may lead to misdiagnosis or missed diagnoses. This study provides new laboratory indicators and cutoff values for the diagnosis of cSLE complicated with MAS. Refining the 2016 sJIA-MAS classification criteria can improve both sensitivity and specificity, thereby contributing to enhancing diagnostic accuracy and timeliness. Key Points • For other autoimmune diseases (such as SLE) associated MAS, there is a lack of widely accepted diagnostic criteria and treatment protocols. • The 2016 sJIA-MAS classification criteria demonstrated both sensitivity and specificity of 90.6% in the diagnosis of cSLE-MAS. • ROC curve analysis revealed that the following cutoff values provided optimal diagnostic differentiation for cSLE-MAS: ferritin ≥ 621.6 µg/L, aspartate aminotransferase ≥ 75.5 U/L, fibrinogen ≤ 1.96 g/L, triglycerides ≥ 2.31 mmol/L, and lactate dehydrogenase ≥ 382 U/L. • Refining the 2016 sJIA-MAS classification criteria can improve the sensitivity to 93.8% and the specificity to 96.9%.