Overweight and obesity accelerate the progression of IgA nephropathy: prognostic utility of a combination of BMI and histopathological parameters

Although more than 40 years have passed since IgA nephropathy (IgAN) was first reported, predicting the renal outcome of individual IgAN patients remains difficult. Emerging epidemiologic evidence indicates that overweight and obesity are risk factors for end-stage renal disease. We aimed to elucidate the outcome of overweight IgAN patients and improve our ability to predict the progression of IgAN based on a combination of body mass index (BMI) and histopathological parameters, including maximal glomerular area (Max GA). Forty-three adult IgAN patients whose estimated glomerular filtration rate was a parts per thousand yen50 ml/min/1.73 m(2) were enrolled in this study. Renal biopsy specimens were evaluated according to the Oxford classification of IgAN. A Kaplan-Meier analysis and the multivariate Cox proportional hazards method were used to evaluate 10-year kidney survival and the impact of covariates. The ability of factors to predict the progression of IgAN was evaluated by their diagnostic odds ratio (DOR). A BMI a parts per thousand yen25 kg/m(2) was found to be an independent predictor of a a parts per thousand yen1.5-fold increase in serum creatinine value (DOR 7.4). The combination of BMI a parts per thousand yen25 kg/m(2), Max GA a parts per thousand yen42,900 mu m(2), and presence of mesangial hypercellularity (Oxford M1) optimally raised predictive power for disease progression of IgAN (DOR 26.0). A combination of BMI a parts per thousand yen25 kg/m(2), the Oxford classification M1, and a Max GA a parts per thousand yen42,900 mu m(2) can serve as a predictor of long-term renal outcome of IgAN.