623 - Characteristics Associated with Use of the Lower Dose “EuroLupus” Cyclophosphamide Regimen in Youth with Proliferative Lupus Nephritis

Poster Number: 623
Publication Number: 623.200

Christine Wang, Children's Hospital of Colorado, Denver, CO, United States; Rebecca E. Sadun, n/a, Durham, NC, United States; Wenru Zhou, University of Colorado, Anschutz campus, Aurora, CO, United States; Kristen Miller, University of Colorado School of Medicine, Aurora, CO, United States; Laura B. lewandowski, Lupus Genetics and Global Disparities Unit, Systemic Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health,, Bethesda, MD, United States; Scott E. Wenderfer, Baylor College of Medicine, Houston, TX, United States; Jennifer C. Cooper, University of Colorado/Children's Hospital Colorado, Aurora, CO, United States

Background: Proliferative lupus nephritis (LN) is a common complication of childhood-onset systemic lupus erythematosus (SLE). In recent years, the EuroLupus Nephritis Trial demonstrated similar effectiveness and decreased ovarian toxicity with a lower dose cyclophosphamide (CYC) regimen. This lower dose “EuroLupus” regimen has now largely replaced the higher dose “NIH” regimen in adults. While many pediatric providers use the EuroLupus regimen, data on treatment practices is lacking.

Objective: To identify demographic and clinical characteristics associated with EuroLupus versus NIH CYC regimen use for treatment of youth with proliferative LN.

Design/Methods: A multisite retrospective cohort study was conducted at 11 North American pediatric centers, enrolling patients 22 years of age or younger with active proliferative LN treated with either the EuroLupus or NIH CYC regimen from July 1, 2014 to June 2021. Patients on dialysis were excluded. Data was extracted via chart review. Demographic and clinical characteristics at the time of treatment start (baseline) were compared. For continuous variables, comparisons were made using two-sample independent t-tests and Wilcoxon rank sum tests for normally and non-normally distributed variables respectively. For categorical variables, Chi-square or Fisher’s exact tests were used. A multivariable generalized linear mixed model with logit link was fit using stepwise selection to identify predictors of receiving the EuroLupus regimen. A random intercept accounted for correlation within sites.

Results: One hundred sixty-four patients (97 NIH, 67 EuroLupus) were included. EuroLupus regimen use increased over time and since 2019 has become the more predominantly used regimen (Figure 1). Older age, shorter distance from the hospital, longer disease duration, and prior CYC use were associated with use of EuroLupus (Table 1). Conversely, new-onset lupus nephritis was more often treated with the NIH regimen (Table 1). Renal parameters were not significantly different between groups. In multivariable analysis (Table 2), lower estimated glomerular filtration rate, female sex, Asian race, and more recent use of CYC were associated with higher odds of receiving the EuroLupus regimen. Concurrent SLE central nervous system involvement and baseline hypertension were associated with lower odds of receiving the EuroLupus regimen.Conclusion(s): Use of the lower dose EuroLupus regimen for treatment of youth with proliferative LN is increasing, especially among female patients with longer disease duration. Further study is needed to compare outcomes between the two treatment regimens.
Figure 1. Cyclophosphamide regimen use over timeEuroLupus regimen use increased over time and since 2019 has become the more predominantly used regimen. Abbreviations: CYC = cyclophosphamide
Table 1: Baseline demographic and clinical characteristics