O004. Assessment of the impact of lupus nephritis on clinical, biological parameters, disease activity and mortality in pediatric Systemic Lupus Erythematosus

Background Systemic lupus erythematosus (SLE) is an autoimmune disorder affecting multiple organ systems. Kidney involvement is one of the most frequent and severe manifestations of pediatric systemic lupus erythematosus (pSLE), seriously affecting the prognosis. It usually manifests as glomerulonephritis of varying severity. Objective: Knowledge of the correlation of lupus nephritis (LN) with clinical, biological, immunological parameters, disease activity and mortality in pediatric systemic lupus erythematosus is limited. This study aims to describe the impact of renal involvement with these different determinants. Methods This was a prospective, multicenter, descriptive 36-month study (January 2015 - December 2018) including patients less than 16 years of age with LN. The presence of LN was defined according to the American College of Rheumatology classification SLE criteria. The LN class was determined by renal biopsy and was classified according to the Morphology in Kidney International Society of Nephrology (ISN)/Renal Pathology Society (RPS) 2004 classification of lupus nephritis. The disease activity was estimated by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), the use of which has been validated in children. Means, percentages and Chi-square tests were specified. P values less than 0.05 were considered statistically significant. Results We included 83 patients in this study. 37/83 patients (44.6%) developed LN with the following urinary signs: 92% of proteinuria (mean 3366.147 mg ± 2785.93 / 24h) including 2/3 of cases of nephrotic syndrome, 81% of hematuria, 14% of acute renal failure with significant reduction in glomerular filtration rate (average creatinine clearance of 32.42 ml / min) and 12% high blood pressure. Out of a total of 30 renal biopsies interpreted at disease diagnosis, 73.4% diffuse proliferative glomerulonephritis forms were observed: (III (30%), IV (36.7%) and VI (6, 7%)). Lupus nephritis were significantly correlated with hypocomplementemia in its C3 (P = 0.00002) and C4 (P = 0.00005) fraction, lymphopenia (P = 0.02), anti-DNA antibodies (P = 0.026), SLEDAI (P = 0.00001) and mortality (P = 0.03). The most frequently used induction drugs for LN classes III, IV and VI were pulsed intravenous methylprednisolone (500 mg daily for 3 doses) in combination with low dose intravenous cyclophosphamide (23%) in the short term (500 mg/m2/15 days X 6) followed by mycophenolate mofetil (28%) (600mg/ m2 in two daily doses) as maintenance treatment associated with a daily dose of oral glucocorticoids with a gradual decrease until reaching the minimum amount necessary to control the disease. All of our SLE patients with nephritis were treated with HCQ with a significant correlation with the decrease in SLEDAI. During the first two years of disease progression, the frequency of LN increased to 43/83 (51.8%) mainly in these severe forms: (IV (41.7%), V (2.8 %). The progression to chronic renal failure had a prevalence of 6, 9% (3/43) of cases; these were mainly patients with severe lupus nephritis (III, and IV) Conclusion Nephritis is a major risk factor for morbidity and mortality in pSLE; LN in children is most often proliferating and more active. The early diagnosis and management of kidney damage are the only guarantee of a good course and prevention of the progression of chronic renal failure. Keywords lupus nephritis; child; systemic lupus erythematosus; disease activity, mortality.