Sex Differences in Clinical Manifestations and Early Flare Outcomes in Korean Patients with Systemic Lupus Erythematosus: A Prospective Single-Center Cohort Study

Objectives: Systemic lupus erythematosus (SLE) predominantly affects females, but sexrelated differences in clinical phenotype and outcomes remain incompletely defined in Asian cohorts.We investigated sex differences in clinical features at diagnosis, disease status at cohort enrollment, and early flare outcomes in a prospective single-center cohort of Korean patients with SLE.Methods: We analyzed 227 patients, including 24 male and 203 female patients.Clinical manifestations and serologic features at diagnosis were compared by sex.Demographic characteristics, comorbidities, disease activity, organ damage, treatment, and patient-reported outcomes at cohort enrollment were also assessed.Logistic regression was used to examine the association between sex and renal involvement at diagnosis.Among patients in lupus low disease activity state at enrollment, first flarefree survival was evaluated using Kaplan-Meier analysis.Findings: No statistically significant sex differences were detected in most clinical and serologic features at diagnosis.However, renal involvement at diagnosis was more frequent in male than in female patients (75% vs. 36%, p<0.001).In logistic regression, male sex was associated with renal involvement in both univariable analysis (odds ratio [OR], 5.23; 95% confidence interval [CI], 1.99-13.76)and age-and smokingadjusted analysis (OR, 4.97; 95% CI, 1.47-16.82),although the CIs were wide.At cohort enrollment, male patients were more likely to have a smoking history and had a higher body mass index, whereas no clear sex-related differences were detected in comorbidities, disease activity, organ damage, treatment patterns, depression, fatigue, and quality of life.Among patients in lupus low disease activity state at enrollment, no statistically significant sex difference in first flare-free survival was detected in an exploratory analysis.Conclusions: In this prospective Korean cohort, renal involvement at diagnosis was more frequent in male patients.Other sex-related differences were not clearly detected, but the small number of male patients and limited flare events warrant cautious interpretation.