Background: The epidemic of obesity has been paralleled by an increase in the incidence of chronic kidney disease. However, epidemiological data for obesity-related glomerulopathy (ORG) from developing countries, including China, are very limited.
Study design: Case series. ORG defined as body mass index (BMI) of 28.0 kg/m(2) or greater; urinary protein excretion of 0.4 g/24 h or greater, and glomerulomegaly (glomerular volume > 3.27 x 10(6) microm(3)) with or without focal segmental glomerulosclerosis (FSGS).
Setting & participants: 10,093 renal biopsy samples from patients obtained from February 2002 to November 2006 at the Research Institute of Nephrology, Nanjing University School of Medicine, China.
Predictor: Obesity defined as a BMI of 28.0 kg/m(2) or greater. Subjects were divided into 3 groups: mild-obesity group with BMI of 28.0 to less than 30 kg/m(2), moderate-obesity group with BMI of 30 to less than 35 kg/m(2), and severe-obesity group with BMI of 35 kg/m(2) or greater.
Outcomes & measurements: Clinicoepidemiological and histopathologic characteristics of patients with ORG at the time of biopsy were described separately.
Results: ORG was observed in 90 biopsy specimens (0.89%); frequency increased from 0.62% to 1.0% during the last 5 years (P = 0.02). Mean age was 37.5 +/- 9.3 (SD) years, 67% were men, mean BMI was 31.2 +/- 3.3 kg/m(2), waist circumference was 103 cm (range, 89.4 to 124 cm) in men and 96.5 cm (range, 88.5 to 113 cm) in women, waist-hip ratio was 0.95 +/- 0.07, and 100% had visceral obesity. Of the total, 49%, 37%, and 14% had mild, moderate, and severe obesity, respectively. Mean urinary protein excretion of subjects was 1.48 +/- 1.2 g/24 h; 51%, 39%, and 10% had proteinuria with protein of 0.4 to 1.0, 1.0 to 3.5, and greater than 3.5 g/d, respectively. Mean measured creatinine clearance (Ccr) was 109 +/- 32.2 mL/min/1.73 m(2), with 42%, 36%, and 22% with a Ccr greater than 120, 90 to 120, and less than 90 mL/min/1.73 m(2), respectively. Glucose dysmetabolism, insulin resistance, dyslipidemia, and hypertension were observed in 77%, 88%, 76%, and 63% of patients, respectively. FSGS was observed in 70%. Mean foot-process width was 534 +/- 176 nm. Foot-process fusion was seen in 36% of patients. Greater BMI was associated with greater proteinuria (P < 0.02), greater Ccr (P < 0.03), and greater foot-process width (P < 0.04).
Limitations: Inability to compute prevalence or incidence from case series. BMI was calculated at time of renal biopsy.
Conclusions: Most patients with ORG had mild obesity, visceral obesity, minor proteinuria, preserved Ccr, and FSGS.