The incidence and prevalence of juvenile idiopathic arthritis differs between ethnic groups in England.

Objectives: JIA is a heterogeneous group of rare autoimmune disorders characterized by chronic joint inflammation of unknown aetiology with onset under 16 years. Accurate estimates of disease rates help understand impacts on individuals and society, and provide evidence for health service planning and delivery. This study aimed to produce the first national estimates of incidence and prevalence by ethnic group using electronic health records.

Methods: Data from the Clinical Practice Research Datalink Aurum, a primary care electronic health record database in England, were used to estimate the incidence and prevalence of JIA by ethnic group amongst children and young people aged under 16 years between 2003 and 2018, with cases validated using Hospital Episode Statistics. χ2 was used to test the difference in proportions compared with the ethnic distribution of England.

Results: A total of 424 incident cases of JIA were identified, 389 validated using Hospital Episode Statistics records. Incidence of JIA was higher amongst those of white ethnic group (6.2 per 100 000 population) compared with mixed (3.0 per 100 000), Asian (2.7 per 100 000) and Black (2.9 per 100 000) communities. The ethnic group distribution of cases differed significantly compared with the general population (P < 0.0001).

Conclusion: The incidence and prevalence of JIA differs between ethnic groups, and is different from the general population. This is likely to be due to a combination of genetic and equity factors. Further research to understand the underlying cause of these differences is important to enable targeted interventions and appropriate service provision.