Development and Validation of a Prediction Rule Using the Oxford Classification in IgA Nephropathy

Abstract

SummaryBackground and objectives The risk assessment for developing ESRD remains limited in patients with IgA nephropathy (IgAN). The aim of this study was to develop and validate a prediction rule for estimating the individual risk of ESRD in patients with IgAN.Design, setting, participants, & measurements A total of 698 patients with IgAN diagnosed by renal biopsy at Kyushu University Hospital (derivation cohort) between 1982 and 2010 were retrospectively followed. The Oxford classification was used to evaluate the pathologic lesions. The risk factors for developing ESRD were evaluated using a Cox proportional hazard model with a stepwise backward elimination method. The prediction rule was verified using data from 702 patients diagnosed at Japanese Red Cross Fukuoka Hospital (validation cohort) between 1979 and 2002.Results In the derivation cohort, 73 patients developed ESRD during the median 4.7-year follow-up. The final prediction model included proteinuria (hazard ratio [HR], 1.30; 95% confidence interval [95% CI], 1.16 to 1.45, every 1 g/24 hours), estimated GFR (HR, 0.84; 95% CI, 0.74 to 0.96, every 10 ml/min per 1.73 m 2 ), mesangial proliferation (HR, 1.85; 95% CI, 1.10 to 3.11), segmental sclerosis (HR, 3.21; 95% CI, 1.37 to 7.51), and interstitial fibrosis/tubular atrophy (T1: HR, 5.30; 95% CI, 2.63 to 10.7; T2: HR, 20.5; 95% CI, 9.05 to 46.5) as independent risk factors for developing ESRD. To create a prediction rule, the score for each variable was weighted by the regression coefficients calculated using the relevant Cox model. The incidence of ESRD increased linearly with increases in the total risk scores (P for trend ,0.001). Furthermore, the prediction rule demonstrated good discrimination (c-statistic=0.89) and calibration (Hosmer-Lemeshow test, P=0.78) in the validation cohort.Conclusions This study developed and validated a new prediction rule using clinical measures and the Oxford classification for developing ESRD in patients with IgAN.

Absence of Mesangial C1q Deposition Is Associated with Resolution of Proteinuria and Hematuria after Tonsillectomy Plus Steroid Pulse Therapy for Immunoglobulin A Nephropathy

“…The clinical severity at the time of the diagnostic renal biopsy was determined according to the clinical grading criteria of the Oxford classification [8,9]. Interstitial fibrosis in the renal cortex was quantified as a ratio (%) of the affected area in the interstitium with Masson's trichrome staining.…”

“…Severe IgAN leads to end-stage renal disease (ESRD) in 30-40% of patients within 20 years of the diagnosis [1]. There are several clinical and histological factors, including arterial hypertension, proteinuria, renal function, smoking, and the Oxford classification score, which determine the final outcome of patients with IgAN [3,4,5,6,7,8,9,10]. …”

Clinical Significance of Crescent Formation in IgA Nephropathy – a Multicenter Validation Study

“…The Oxford classification, the pathologic scoring system for IgAN, has been widely used and its predictive value has been confirmed by other studies [9-13]. Recently, there was a major update in the Oxford classification system, and the presence of cellular or fibrocellular crescent was added to the graded parameters, consisting of the MEST-C scores [14].…”

Serum Matrix Metalloproteinase-7 Level is Associated with Fibrosis and Renal Survival in Patients with IgA Nephropathy

“…Based on renal biopsy, the Oxford IgAN classification was formulated and represents a valuable prognostic tool for IgAN [13]. Interstitial fibrosis is one of the most important histological indicators, confirmed by a large number of original studies [14, 15]. However, noninvasive markers of IgAN with prognostic value are still scarce, which will be of great significance for current clinical work.…”