Incidence and prevalence of systemic lupus erythematosus in New Zealand from the national administrative datasets

OBJECTIVES: This study aims to provide updated data on the incidence and prevalence of systemic lupus erythematosus (SLE) in New Zealand and to examine the difference between ethnic groups. METHODS: We identified the SLE cases from the national administrative datasets. The date of first identification of SLE was the earliest date of a related inpatient event or the earliest date of a related outpatient event. The crude incidence and prevalence of SLE in 2010–2021 were estimated by gender, age group and ethnicity. The WHO (World Health Organization) age-standardised rate (ASR) of incidence and prevalence of SLE was calculated, after stratifying the cases by ethnicity and gender. RESULTS: The average ASR of incidence and prevalence of SLE in 2010–2021 was 2.1 and 42.1 per 100,000 people in New Zealand. The average ASR of incidence for women was 3.4 per 100,000 for women and 0.6 for men. It was highest for Pacific women (9.8), followed by Asian women (5.3) and Māori women (3.6), and was lowest for Europeans/Others (2.1). The average ASR of prevalence was 65.2 per 100,000 for women and 8.5 for men. It was highest for Pacific women (176.2), followed by Māori women (83.7) and Asian women (72.2), and was lowest for Europeans/Others (48.5). The ASR of prevalence of SLE has been increasing slightly over time: from 60.2 in 2010 to 66.1 per 100,000 in 2021 for women and from 7.6 in 2010 to 8.8 per 100,000 in 2021 for men. CONCLUSION: The incidence and prevalence of SLE in New Zealand were comparable to the rates in European countries. Pacific people had the highest incidence and prevalence of SLE, more than three times the rates for Europeans/others. The high incidence of SLE in Māori and Asian people also has implications for the future as these populations increase as a proportion to the total population.