Excessive body weight as a new independent risk factor for clinical and pathological progression in primary IgA nephritis

Experimental evidence suggests a role for obesity in the formation and prog ression of some glomerular lesions, but data for human glomerulonephritis a re lacking. In a cohort of 162 incident patients with biopsy-proven immunog lobulin A (IgA) nephropathy, we assessed whether the presence of an elevate d body mass index (BMI greater than or equal to 25 kg/m(2)) at the time of the first renal biopsy (RB1) correlated with clinical data at RB1 (24-hour proteinuria, arterial hypertension, and renal function), pathological data (global optical score [GOS] with detailed pathological indices), and clinic al progression to both arterial hypertension and chronic renal failure (CRF ). In both univariate and multivariate analyses, the presence of an elevate d BMI at RB1 was significantly associated with the severity of pathological renal lesions (GOS and vascular, tubular, and interstitial indices). Hyper tension-free survival was significantly less in overweight patients (P < 0. 0001) compared with those with normal weight. In a Cox regression analysis for hypertension-free survival including 24-hour proteinuria greater than 1 g, GOS, and metabolic parameters, only elevated BMI and GOS were independe nt factors for the development of arterial hypertension. CRF-free survival was also significantly less in patients with an excessive BMI. In a multiva riate Cox regression analysis for CRF-free survival, hypertension, GOS, and BMI at RB1 were independent risk factors for CRF. In IgA nephropathy, exce ssive body weight and/or BMI are underestimated predictive factors for the development of arterial hypertension and, ultimately, CRF. (C) 2001 by the National Kidney Foundation, Inc.