Epidemiology and complications of rheumatoid arthritis in the Indigenous Australian population

Rheumatoid Arthritis (RA) can present differently in Indigenous populations. Data on RA in Indigenous Australians (IA) are almost non-existent. A population-based cohort study of disease incidence (IR) and point prevalence (PR) rates per 100.000 and clinical outcomes in IA patients hospitalised with RA compared to non-Indigenous (NI) patients with RA using longitudinal administrative health data over 30 years. For IA patients (n = 282) the RA IR was 23.52 (CI 14.99-35.14) which did not differ from the IR in NI patients 27.85 (CI 18.48-40.29) (p = 0.67) with the 2015-point PR in IA at 373.5 (CI 336.5-413.3) versus 375.3 (CI 338.3-145.2) in the NI population (p = 0.91). At index admission, IA patients with RA were younger, more often smokers with a higher prevalence of diabetes mellitus and obesity. Over the disease course, IA patients had lower readmission and ED visits rates for RA, were less likely to undergo joint surgery and had lower rates of confirmed osteoporosis, despite higher fracture rates. In contrast, extraarticular RA manifestations were as frequent in both groups. The age adjusted standardised mortality rate ratio was higher in IA patients (3.42, CI 3.43-8.03) with cardiovascular events the prominent cause of death in both groups. RA is as frequent in the IA population of Australia as in the NI population. However, IA patients with RA present at younger age, have similar rates of extraarticular manifestations, but receive less rheumatological care and experience higher mortality.