Association of Inflammatory Biomarkers and Ferritin With Severity of Pediatric Systemic Lupus Erythematosus Patients

Pediatric Systemic Lupus Erythematosus (pSLE) is a chronic autoimmune disorder characterized by innate and adaptive immune activation, leading to autoantibody production, immune complex deposition, and systemic inflammation. Disease activity in pSLE is typically variable and fluctuating, requiring accurate and regular monitoring to optimize immunosuppressive therapy, prevent organ damage accumulation, and avoid treatment toxicity. Although the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) is widely established for assessing disease activity, its calculation relies on comprehensive clinical evaluations and specialized laboratory parameters (such as anti-dsDNA and complement levels) that may not be routinely available at every clinical encounter. Hematological indices derived from routine complete blood counts specifically the Systemic Immune-Inflammation Index (SII), Neutrophil-to-Lymphocyte Ratio (NLR), and Platelet-to-Lymphocyte Ratio (PLR) along with serum ferritin (an acute phase reactant), reflect systemic inflammatory and immune dysregulation. These parameters represent low-cost, rapidly accessible, and widely available potential biomarkers for disease activity. This observational study aims to evaluate the associations of SII, ferritin, NLR, and PLR with disease severity in pediatric SLE patients. Disease severity will be primarily categorized into mild, moderate, and severe stages based on the SLEDAI-2K score and analyzed as ordinal data, with secondary numerical SLEDAI-2K score analyses. Because circulating blood cell counts and ferritin concentrations can also be influenced by non-SLE factors such as active infections, Macrophage Activation Syndrome (MAS), nutritional status, underlying hematological disorders, malignancies, and corticosteroid administration these clinical confounders will be rigorously evaluated and considered during statistical interpretation. The observed associations will be evaluated statistically to assess their potential clinical utility as supplementary markers for pSLE disease activity monitoring.