Comparison of renal response parameters for juvenile membranous plus proliferative lupus nephritis versus isolated proliferative lupus nephritis: a cross-sectional analysis of the CARRA Registry.

Lupus nephritis (LN) affects many patients with juvenile systemic lupus erythematosus (SLE) and is a significant cause of disease morbidity. Membranous plus proliferative LN (M + PLN) may represent a more difficult to treat subtype of juvenile LN, compared to isolated proliferative LN (PLN). In this retrospective observational study, we utilized data from the Childhood Arthritis and Rheumatism Research Alliance (CARRA) registry to compare response rates for pediatric M + PLN versus PLN. Response was assessed at the most recent CARRA registry visit gathered ≥6 months after diagnostic kidney biopsy. Estimated glomerular filtration rate (GFR) less than 90 ml/min/1.73 m(2), indicating renal insufficiency, was found in 16.1% of patients with M + PLN and 6.1% of patients with PLN (P = 0.071). We found no significant difference in achievement of response in either hematuria or proteinuria between PLN and M + PLN groups or between subgroups determined by presence of class III vs. class IV proliferative disease. Exposure rates to mycophenolate, cyclophosphamide, and rituximab were similar between groups. Future studies will be necessary to correlate pediatric LN renal histology data with treatment response as well as other disease outcome measures.