Background: Obesity is a risk factor for chronic kidney disease. Although body mass index (BMI) or waist circumference is indicators of obesity, actual measurements of visceral fat area (VFA) more accurately reflect the amount of visceral fat. We aimed to determine the most sensitive obesity indicator for predicting renal impairment among VFA, BMI, waist circumference, waist-to-height ratio, and visceral-to-subcutaneous fat ratio (VSR).
Methods: Subjects who underwent VFA measurements during health checkups in 2012 were included. Obesity was defined using a separate baseline value for each indicator [VFA (100 cm2), BMI (25 kg/m2), waist circumference (85 cm for men and 90 cm for women), waist-to-height ratio (0.5), VSR (0.4)]. Changes in estimated glomerular filtration rate (eGFRcr) and time to new-onset proteinuria were measured. The relationships between obesity indicators and eGFRcr were evaluated using a linear mixed-effects model. The relationships between obesity indicators and new-onset proteinuria were evaluated using Poisson regression analysis.
Results: Analysis was performed on 2753 subjects (mean age 50.3 years). The VFA ≥ 100 cm2 group exhibited a larger annual difference in eGFRcr compared to the < 100 cm2 group (- 0.24 mL/min/1.73 m2, P = 0.03). There was a statistically significant difference in the proteinuria incidence rate ratio, which was 1.54 times (95% confidence interval 1.01-2.35) in the VFA ≥ 100 cm2 group. Statistically significant correlations were not observed with any of the other obesity indicators.
Conclusion: VFA is suggested to be the most sensitive obesity indicator for decline in kidney function and new-onset proteinuria.
Keywords: Chronic kidney disease; Obesity; Proteinuria; Renal impairment; Visceral fat area.