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

ObjectiveWe 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.MethodsA total of 285 AAGN patients with biopsy-proven 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.ResultsOver a median follow-up period of 41.3 (20.0-63.8) months, 84 (29.5%) patients reached endstage kidney disease (ESKD). In the development set, hypertension (HR=2.163, 95%CI 1.083-4.322, P=0.029), high serum creatinine (HR=1.002, 95%CI 1.001-1.003, P<0.001), high daily urine protein (HR=1.343, 95%CI 1.148-1.571, P<0.001), high glomerular sclerosis (HR=13.983, 95%CI 3.496-55.923, P<0.001), and interstitial fibrosis>50% (HR=4.179, 95%CI 1.900-9.192, 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 (0.785-0.891), 0.794 (0.774- 0.814), and 0.822 (0.775-0.869), respectively, which were higher than those of the renal risk score model, 0.801 (0.748-0.854), 0.746 (0.654-0.838) and 0.783 (0.736-0.830), respectively. And the net reclassification improvement and the integrated discrimination improvement further illustrated the higher predictive ability of the nomogram.ConclusionWe present a nomogram as a practical tool to predict renal outcomes in Chinese patients with an MPO-ANCA glomerulonephritis.

From Prediction Tools to Precision Medicine in Antineutrophil Cytoplasmic Antibody–Associated Vasculitis

“…14 The measure used for these models is an extension, Harrell C, which is used for time-to-event studies. Ni et al 3 found that, in their cohort, the ARRS retained strong discriminative ability at C = 0.783, and the nomogram's performance was C = 0.822. The nomogram uses 5 more parameters, and as the number of parameters increases, so does the risk of overfitting.…”

“…In this issue of The Journal of Rheumatology, Ni et al 3 present a new nomogram model for clinical prediction in ANCA-GN. Three prediction models have already been proposed: the Berden classification 4 based on glomerular pathology, the Mayo Clinic Chronicity Score (MCCS) 5 based on 4 components of chronic scarring, and the ANCA Renal Risk Score (ARRS), 6 which uses a combination of histopathologic parameters and biochemical indicators.…”

“…4,6 The MCCS used a North American cohort and Ni et al now a Chinese single-center retrospective cohort. 3,5 The nomogram is similar to the ARRS as it uses the parameters percentage of normal glomeruli and creatinine (for kidney function, instead of eGFR). It incorporates interstitial fibrosis but not tubular atrophy.…”

“…Ni et al used a cohort of mainly myeloperoxidase (MPO)-positive patients and could therefore not investigate the effect of the antibody subtype. 3 Histopathological studies have demonstrated the influence of the fresh fibrinoid necrosis and cellular crescents on the recovery of kidney function. 7,8 In the current study, 3 acute vasculitic lesions did not affect outcome prediction, but further lesions of chronicity were added to the tool.…”

“…3 Histopathological studies have demonstrated the influence of the fresh fibrinoid necrosis and cellular crescents on the recovery of kidney function. 7,8 In the current study, 3 acute vasculitic lesions did not affect outcome prediction, but further lesions of chronicity were added to the tool.…”