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.

Histopathology pattern and survival analysis of patients with kidney biopsy in the top end of Northern Australia from 2007 to 2020.

AIM: Royal Darwin Hospital (RDH) is the main tertiary hospital that has performed more than 600 biopsies since its establishment. Although Indigenous people in Australia's Northern Territory (NT) has the highest rate of renal replacement therapy, the histopathology pattern of their renal diseases is still under discussed. We aimed to analyse the histopathology pattern of patients undergoing renal biopsy in RDH from June 2007 to June 2020. Secondary aims include clinical indication and survival analysis of patients with kidney biopsies. METHODS: We conducted a retrospective cohort study on all native kidney biopsy reports from patients over the age of 16, from June 2007 to June 2020. Descriptive statistics was used to summarise age, sex, indigeneity, histopathological pattern, and mortality. Categorical values were expressed as absolute frequencies and percentages. Survival analysis was performed using multivariate analyses and Cox proportional hazard regression model. RESULTS: There were 364 native renal biopsies included in the analysis. Sub-nephrotic proteinuria was the most common clinical indication for kidney biopsy (n = 160,47.8%). Diabetes nephropathy (DN) was the most common pathological finding (n = 71,12.8%). Indigenous population who had dialysis performs poorly compared to their non-indigenous counterpart (HR 2.37,95% CI 1.53-3.67,p < 0.001). CONCLUSION: Diabetic nephropathy is the most common native kidney biopsy in the NT with higher mortality among indigenous patients. This study supports the previous findings of indigenous female excess, younger age of kidney disease requiring kidney biopsy, and excess of diabetic nephropathy in the top-end of the NT. It can be speculated that some diabetic patients had atypical features prompting a biopsy.

Induction therapy and outcome of proliferative lupus nephritis in the top end of Northern Australia - a single centre study retrospective study.

BACKGROUND: Lupus nephritis is a common manifestation of Systemic Lupus Erythematosus. Mycophenolate is recommended by guidelines for induction therapy in patients with proliferative lupus nephritis and nephrotic range proteinuria Class V lupus nephritis. Indigenous Australians suffer disproportionally from systemic lupus erythematosus compared to non-Indigenous Australians (Anstey et al., Aust N Z J Med 23:646-651, 1993; Segasothy et al., Lupus 10:439-444, 2001; Bossingham, Lupus 12:327-331, 2003; Grennan et al., Aust N Z J Med 25:182-183, 1995). METHODS: We retrospectively identified patients with newly diagnosed biopsy-proven class III lupus nephritis, class IV lupus nephritis and class V lupus nephritis with nephrotic range proteinuria from 1st Jan 2010 to 31st Dec 2019 in our institution and examined for the patterns of prescribed induction therapy and clinical outcome. The primary efficacy outcome of interest was the incidence of complete response (CR) and partial response (PR) at one-year post diagnosis as defined by the Kidney Disease: Improving Global Outcome (KDIGO) guideline. Secondary efficacy outcome was a composite of renal adverse outcome in the follow-up period. Adverse effect outcome of interest was any hospitalisations secondary to infections in the follow-up period. Continuous variables were compared using Student's t-test or Mann-Whitney U-test. Categorical variables were summarised using frequencies and percentages and assessed by Fisher's exact test. Time-to-event data was compared using the Kaplan-Meier method and Log-rank test. Count data were assessed using the Poisson's regression method and expressed as incident rate ratio. RESULTS: Twenty of the 23 patients included in the analysis were managed with mycophenolate induction upfront. Indigenous Australian patients (N = 15), compared to non-Indigenous patients (N = 5) received lower cumulative dose of mycophenolate mofetil over the 24 weeks (375 g vs. 256 g, p < 0.05), had a non-significant lower incidence of complete remission at 12 months (60% vs. 40%, p = 0.617), higher incidence of composite renal adverse outcome (0/5 patients vs. 5/15 patients, p = 0.20) and higher incidence of infection related hospitalisations, (incident rate ratio 3.66, 95% confidence interval 0.89-15.09, p = 0.073). CONCLUSION: Mycophenolate as upfront induction in Indigenous Australian patients were associated with lower incidence of remission and higher incidence of adverse outcomes. These observations bring the safety and efficacy profile of mycophenolate in Indigenous Australians into question.