Retrospective analysis of clinical and pathomorphological features of lupus nephritis in children

Purpose: The aim of the study was to evaluate the clinical course and pathomorphological correlations in Polish children with the diagnosis of lupus nephritis (LN). Methods: We retrospectively analyzed the medical records of 39 children hospitalized due to LN in 7 pediatric nephrology units in Poland between 2010 and 2019. Demographic data, clinical symptoms at the onset of LN and laboratory parameters were reviewed. We analyzed Systemic Lupus Erythematosus Disease Activity Index (SLE-DAI), histological LN findings with the activity (IA) and chronicity index (IC). Results: We examined 32 girls and 7 boys, median age at LN onset was 14.75 (IQR 13.0-16.0) years, SLEDAI of 22.0 (IQR 18.0-27.0) points; LN histological class: IV (59.4%), III (18.9%), III/V (10.8%), IV/V (8.1%), VI (2.7%); IA 8.0 (IQR 6.0-11.0) points, IC 1.05 (IQR 0-2.0) points. Children with nephrotic (n = 22) and non-nephrotic (n = 17) proteinuria differed in median Hb level (9.55, IQR 8.3-11.2 vs 10.9, IQR 10.1-11.6 g/L; P < 0.05), albumin level (2.5, IQR 2.1-3.19 vs 3.6, IQR 3.4-4.1 g/dL; P < 0.001), proteinuria (5.76, IQR 3.0-7.5 vs 1.08, IQR 0.53-1.50 g/day; P < 0.0001), eGFR (53.9, IQR 27.0-68.8 vs 96.7, IQR 73.8-106.2 mL/min/1.73 m(2); P < 0.01) and occurrence of hypertension (77% vs 23%; P < 0.01). In multivariate analysis Hb level (beta = 8.0; 95%CI, 1.90-14.11) was the significant predictor of eGFR<90 mL/min/1.73 m(2). Conclusions: Proliferative forms of LN in children may have a varying clinical presentation. Children with LN with nephrotic range proteinuria have lower Hb level, lower eGFR and higher occurrence of hypertension. Hb level is the significant predictor of eGFR<90 mL/min/1.73 m(2) in children with LN.