Ethnic Differences in Pediatric Systemic Lupus Erythematosus

Abstract

Prevalence and severity of systemic lupus erythematosus (SLE) in adults is suggested to be distinctly different between ethnic groups. The impact of ethnicity is not as well delineated in pediatric SLE (pSLE). We compared prevalence and extent of major organ involvement, disease activity, and damage in pSLE between different ethnic groups. Ethnic demographic profiles of an inception cohort of 265 patients with pSLE followed at Sick Kids Hospital in Toronto were determined and compared to the Metropolitan Toronto at-risk population. Patients were categorized into ethnic subsets based on self-designated ethnic origins. Disease characteristics including major organ involvement, disease activity, and damage measures were longitudinally determined and compared among ethnic groups. Ethnicity data were available on 259/265 pSLE patients (99.6%); the majority were non-Caucasian (60%) compared to the Metropolitan Toronto at-risk population (40%) (p < 0.0001). Non-Caucasian patients were younger at diagnosis than Caucasian patients, Black patients being the youngest at diagnosis (12.6 vs 14.6 yrs; p = 0.007). Renal disease was significantly more common in non-Caucasian than in Caucasian pSLE patients (62% vs 45%; p = 0.01). There was a trend toward increased prevalence of central nervous system disease in Black patients compared to Asian patients (p = 0.108). There was no difference in gender ratio, SLE Disease Activity Index, or damage scores between ethnic groups. Non-Caucasian ethnicity is associated with increased pSLE disease prevalence. Non-Caucasian pSLE patients were significantly younger and more likely to have nephritis. However, disease activity and damage were strongly associated with major organ disease independent of the patient's ethnicity.