Unveiling the dual nature of late-onset systemic lupus erythematosus: A cross-sectional study.

Background and Objective: Systemic lupus erythematosus (SLE) is a complex, heterogeneous autoimmune disease whose presentation can vary widely with patient age. While SLE in young adults has been extensively characterized, less is known about phenotypes of late-onset SLE. Methods: This study aimed to characterize the features of late-onset SLE patients in a Chinese cross-sectional study. Patients diagnosed with SLE at age 50 years or older were classified as having late-onset SLE. Early-onset SLE patients from the same cohort were included as controls. Demographic, clinical, and laboratory data were collected, and a two-step cluster analysis was employed to categorize late-onset SLE patients. Results: A total of 141 patients (27.48%) were classified as late-onset SLE. The onset of lupus in late-onset patients is more insidious, they exhibited lower systemic lupus erythematosus disease activity index-2000 (SLEDAI-2K) scores, and had significantly fewer instances of fever, mucocutaneous, and positive of antibodies compared to early-onset SLE (all Conclusion: This study refines our understanding of late-onset SLE by delineating two subgroups and suggests that age-stratified approaches to diagnosis and management may improve patient care.