Supplementary Material for: Evaluating sex differences in the characteristics and outcomes of lupus nephritis: a systematic review and meta-analysis

Introduction: More frequent and severe lupus nephritis (LN) has been reported in men compared to women but data are limited and inconsistent. We conducted a meta-analysis of the literature to compare the histopathologic findings and outcomes between men and women with biopsy-proven LN. Methods: A systematic search of MEDLINE, Embase, Cochrane, and Web of Science databases was conducted through February 2021. Clinical information was extracted and synthesized from 25 studies that met inclusion criteria (1210 men and 6635 women). Pooled odds ratios (OR) with corresponding 95% confidence intervals (CI) were generated via meta-analysis, and meta-regression was performed to assess the impact of several covariates, both using random-effects models. Results: Twenty studies reported kidney histopathology, eleven reported kidney outcomes and eight reported mortality rates. Men had greater odds of class IV ± V LN (OR 1.26, 95% CI 1.01-1.56), and the composite of end-stage kidney disease, persistent eGFR <15 mL/min or doubling of serum creatinine (OR 2.20, 95% CI 1.59-3.06), and lower odds of complete remission (OR 0.52, 95% CI 0.39-0.68). Mortality was not statistically significantly different between sexes (OR 1.50, 95% CI 0.92-2.46). Meta-regression did not reveal statistically significant study-level relationships between sex differences in any of the covariates that could account for the greater odds of worse kidney outcome in males. Conclusion: Our analysis confirms the association between male sex and increased severity of LN as well as worse kidney outcomes. Larger prospective studies are needed to validate this association and inform treatment strategies adapted to this population.