Comparative Analysis of Damage Accrual in Lupus Nephritis Stratified by Biological Sex.

Abstract

OBJECTIVE Several studies in systemic lupus erythematosus (SLE) have suggested that male individuals may experience a higher risk of damage compared to female individuals. However, this has not been adequately explored in cohorts focused specifically on lupus nephritis (LN). We aimed to investigate sex-based differences in the accrual of both extrarenal and renal damage in a cohort of patients with LN. METHODS This retrospective study included patients with SLE from an observational cohort who developed LN at or after clinic entry. Outcomes of extrarenal and renal damage were assessed using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) and kidney function measures. Statistical analyses included Fine-Gray subdistribution hazard models and Kaplan-Meier survival analysis. RESULTS The cohort included 460 patients, with a predominance of female individuals (83.5%) and a median age of 33 years. Over a median follow-up of 8.6 years, 45.3% of patients accrued extrarenal damage, defined as an increase in nonrenal SDI by ≥ 1, whereas 32.2% experienced renal damage, defined as a composite of either a sustained ≥ 30% decline in estimated glomerular filtration rate or progression to end-stage kidney disease. No significant differences in the accrual of damage were observed between male and female individuals, and the time to outcomes was not statistically different between both sexes. Multivariable analysis revealed that male sex was not associated with higher damage accrual, either extrarenal (hazard ratio [HR] 1.13, 95% CI 0.76-1.70) or renal (HR 1.26, 95% CI 0.67-2.36). CONCLUSION Extrarenal and renal damage accrual are frequent in patients with LN and do not appear to be higher in male individuals.