Variations in clinical presentation and biomarkers among biopsy-proven lupus nephritis patients: a Top End retrospective cohort study

Background Lupus nephritis (LN) is a common feature of systemic lupus erythematosus (SLE) and affects 50% of patients with SLE. Racial differences in incidence and prevalence have been well documented worldwide. In Australia, higher incidence and prevalence of SLE had been previously reported in Aboriginal and Torres Strait Australians compared with non-Indigenous Australians. Aim To describe the differences in clinical features and lupus biomarkers between Aboriginal and Torres Strait Islander Australian and non-Indigenous Australian patients with LN. Methods We retrospectively identified all consecutive biopsy-proven LN patients in our institution and compared the clinical features and lupus biomarkers between Aboriginal and Torres Strait Islander Australians and non-Indigenous Australians. Results Of the 33 consecutive biopsy-proven LN patients, 26 self-identified as of Aboriginal and Torres Strait Islander descent. The estimated incidence of LN in Aboriginal and Torres Strait Islander Australian and non-Indigenous Australians were 5.08 and 0.47 per 100 000 patient-years respectively. Neurological manifestations (23.08% vs 0%), haematological manifestations (46.50% vs 16.67) and right-heart catheter proven pulmonary arterial hypertension (23.08% vs 0%) were more frequently observed among Indigenous Australian patients compared with non-Indigenous Australian patients. The incidence of positive extractable nuclear antigen was also higher among Indigenous Australian patients (84.62% vs 57.14%). Conclusion The present study further supports the observation that lupus in Aboriginal and Torres Strait Islander Australians were of a 'distinct phenotype' compared with non-Indigenous Australians. Future research should be aimed at delineating the reason for this observed difference.