Validation of the Antineutrophil Cytoplasmic Antibody Renal Risk Score and Modification of the Score in a Chinese Cohort With a Majority of Myeloperoxidase-Positive Patients

Abstract

Objective. We aimed to validate and modify the renal risk score for antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (AAGN) in a Chinese cohort with a majority of myeloperoxidase (MPO)-positive patients. Methods. A total of 285 patients with biopsy-proven AAGN in our center were retrospectively included. Patients were randomly assigned to the development set (n = 201) and the validation set (n = 84). We calculated the renal risk score and analyzed the clinicopathological characteristics and follow-up data. The nomogram was constructed based on the independent prognostic factors identified by the multivariable Cox regression and then compared with the renal risk score. Results. Over a median follow-up period of 41.3 (range 20.0-63.8) months, 84 (29.5%) patients reached end-stage kidney disease (ESKD). In the development set, hypertension (hazard ratio [HR] 2.16, 95% CI 1.08-4.32, P = 0.03), high serum creatinine (HR 1.002, 95% CI 1.001-1.003, P < 0.001), high daily urine protein (HR 1.34, 95% CI 1.15-1.57, P < 0.001), high glomerular sclerosis (HR 13.98, 95% CI 3.50-55.92, P < 0.001), and interstitial fibrosis > 50% (HR 4.18, 95% CI 1.90-9.19, P < 0.001) were independent risk factors for ESKD, and these indicators were included in the nomogram. The C-indices of the nomogram model in the development set, validation set, and all-data set were 0.838 (range 0.785-0.891), 0.794 (range 0.774-0.814), and 0.822 (range 0.775-0.869), respectively, which were higher than those of the renal risk score model, 0.801 (range 0.748-0.854), 0.746 (range 0.654-0.838) and 0.783 (range 0.736-0.830), respectively. The net reclassification improvement and the integrated discrimination improvement further illustrated the higher predictive ability of the nomogram. Conclusion. We present a nomogram as a practical tool to predict renal outcomes in Chinese patients with MPO-ANCA glomerulonephritis.