Lupus nephritis outcomes in Aotearoa New Zealand, a retrospective case series

Aims Lupus nephritis (LN) is common in systemic lupus erythematosus (SLE) and is associated with adverse renal outcomes and premature mortality. There is limited data examining LN outcomes in Aotearoa New Zealand and none examining outcomes since mycophenolate mofetil (MMF) became subsidised for use in class III/IV LN induction. We describe a cohort of adults with biopsy-confirmed LN over an 18-year period in two regions of Aotearoa New Zealand, including LN characteristics, treatment, and outcomes. Methods Cases were identified from laboratory databases and relevant data extracted from patient records. Response was defined per Kidney Disease, Improving Global Outcomes (KDIGO) with overall renal response (ORR) defined as at least partial response (PR). Outcomes among patients with class III/IV LN were explored by induction treatment and timing of MMF restrictions. Results One hundred cases were identified, including 74 with class III/IV LN. Most (85/100) were women, living in urban areas (78%), with ethnicities including Māori (25%), Pacific (13%) and NZ European (38%). The median age at LN diagnosis was 38 years (range 18-74) and the median time between SLE diagnosis and renal biopsy was 2 years. In the MMF-restricted period, MMF was used for induction in class III/IV LN in 43% (12/28) of cases, and in 72% (33/46) of cases in the MMF-unrestricted period ( p = .01). In the MMF-unrestricted period, use of high dose cyclophosphamide stopped (18% to 0%), complete response (CR) rates doubled (14% to 33%, p = .08) whereas rates of ORR did not show statistically significant change (39% to 50%, p = .37). At last-observed follow up (mean 7 years from biopsy) 26/74 (36% cases) had poor outcomes with no renal response. Conclusion In this LN cohort in Aotearoa New Zealand, half of people with LN class III/IV do not achieve early renal response and over one-third have poor outcomes over less than a decade of follow up. Subsidy of MMF substantively increased its use and patients in this time period had better rates of good LN outcomes. These data suggest considerable unmet need for effective treatments for LN and that funding of effective medicine for LN increases their use and improves LN outcomes.