Predicting prognosis in ANCA-associated vasculitis with kidney involvement.

Area of Science:

• Nephrology
• Immunology
• Rheumatology

Background:

• Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) often involves kidney complications, necessitating accurate prognostication.
• The ANCA Kidney Risk Score (AKRiS) was introduced in 2023 to enhance prediction of kidney outcomes in AAV patients.
• The prognostic accuracy of AKRiS may be further improved by incorporating additional predictors of kidney survival.

Purpose of the Study:

• To evaluate the prognostic performance of the AKRiS in a multicentric cohort of AAV patients with kidney involvement.
• To assess whether incorporating recently identified predictors of kidney survival can refine the AKRiS's accuracy in predicting kidney failure.

Main Methods:

• Retrospective review of incident AAV cases with kidney biopsy between 2005 and 2020.
• Cox regression analysis to identify factors associated with kidney failure, including AKRiS and post-induction parameters.
• Area under the receiver operating characteristic curve (AUROC) analysis to compare the predictive accuracy of AKRiS alone and in combination with other factors.

Main Results:

• The cohort comprised 115 AAV patients; 34% progressed to kidney failure during a median 6.4-year follow-up.
• Independently associated with kidney failure after adjusting for AKRiS were: dialysis within 4 weeks (HR 6.20), post-induction eGFR (HR 0.94), and post-induction UPCR (HR 1.62).
• The AUROC for kidney failure prediction was 0.77 for AKRiS alone, increasing to 0.82 with the addition of dialysis within 4 weeks, 0.80 with post-induction eGFR, and 0.79 with post-induction UPCR.

Conclusions:

• Dialysis within 4 weeks, post-induction eGFR, and post-induction UPCR are significant predictors of long-term kidney outcomes in AAV patients.
• These factors modestly enhance the predictive power of the AKRiS for kidney failure.
• The study proposes using these variables as placeholder endpoints for kidney failure in future AAV research.