The incidence, diagnostic clinical manifestations and severity of juvenile systemic lupus erythematosus in New Zealand Maori and Pacific Island children: the Starship experience (2000-2010)

Objectives: To describe the incidence, diagnostic clinical manifestations and severity of juvenile systemic lupus erythematosus (jSLE) in a cohort of New Zealand Maori and Pacific Island children compared to European children.

Methods: A chart review was conducted of children with jSLE seen by the Starship paediatric rheumatology and/or renal services between January 2000 and November 2010. Diagnostic clinical data and lupus nephritis data at anytime were collated while classic British Isles Lupus Assessment Group (BILAG) and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores were derived retrospectively.

Results: Thirty-two children were diagnosed with jSLE with an annual incidence of 0.52 per 100,000 per year. Compared with European children (0.31 per 100,000 per year) the incidence of jSLE was higher among Maori and Pacific (0.67 per 100,000 per year, p=0.06) and significantly higher among Asian children (1.17 per 100,000 per year, p=0.01). Compared with European children, Maori and Pacific children were more frequently diagnosed with lupus nephritis (80% vs 40%, p=0.09) and severe (WHO class 4 or 5) renal lesions (60% vs 40%, p=0.43) at presentation. Similarly, at any time during the study, lupus nephritis (100% vs 40%, p=0.001) and severe (WHO class 4 or 5) renal lesions (73.3% vs 40%, p=0.12) were more frequent among Maori and Pacific compared with European children. Furthermore, retrospective BILAG assessment of diagnostic disease severity demonstrated that Maori and Pacific children experienced the majority of severe "Category A" disease (56.8% vs 22.7%, p=0.17) which was predominantly renal (73.3% vs 40%, p=0.12) in nature.

Conclusions: This is the first description of the incidence and clinical manifestations of jSLE in a cohort of New Zealand children. Although limited by the small numbers involved it confirmed anecdotal suspicions that the incidence of jSLE among Maori, Pacific and Asian children is higher than European children. Lupus nephritis is also more frequent and severe in Maori and Pacific children.