Clinical Significance of Adjusting the Estimated Glomerular Filtration Rate by an Individual’s Body Surface Area from the Perspective of the Cardio-ankle Vascular Index: A Cross-sectional Study

Abstract

Aim: A decline in the estimated glomerular filtration rate (eGFR) is associated with vascular dysfunction, a cardiovascular disease (CVD) risk. However, since the eGFR is based on the standard body surface area (BSA) of 1.73 m², its reliability may be affected by body size. We aimed to clarify whether the individual’s BSA adjustment of eGFR enhances the relationship with kidney and vascular functions in the general healthy Japanese population.

Methods: This cross-sectional analysis was conducted in a total of 58,837 Japanese individuals. The BSA-adjusted eGFR (mL/min) was defined as the product of the conventional eGFR and the individual’s BSA divided by 1.73 m². Arterial stiffness was assessed by the cardio-ankle vascular index (CAVI), and a high CAVI was defined as CAVI ≥ 9.0.

Results: Compared with the eGFR, the BSA-adjusted eGFR showed higher values in males in their 20s to 50s and lower values in females of all ages. The BSA-adjusted eGFR showed a stronger negative correlation with the CAVI than the eGFR (R: –0.444 vs. –0.388 in males, –0.449 vs. –0.416 in females). In a receiver-operating characteristic curve analysis, the discriminative power for a high CAVI was stronger for the BSA-adjusted eGFR than for the eGFR (area under the curve: 0.776 vs. 0.723 in males, 0.757 vs. 0.716 in females). The upper tertile of the BSA-adjusted eGFR showed higher odds ratios for a high CAVI than that of the eGFR in both sexes, after adjusting for covariates.

Conclusions: The BSA-adjusted eGFR appropriately assesses the kidney function according to differences in sex, age and body size. Furthermore, a CAVI analysis suggested that the BSA-adjusted eGFR might facilitate the achievement of more precise preventive care for CVD.