Comparison of predictive value for first cardiovascular event between Japanese GFR equation and coefficient-modified CKD-EPI equation

Background: The most superior GFR-estimating equation from the viewpoint of cardiovascular disease (CVD) prediction remains unclear. Thus, we performed cross-sectional comparison between two GFR-estimating equations (Japanese GFR equation and coefficient-modified CKD-EPI equation) and CVD incidence using Japanese nationwide "specific health checkup" data.

Methods: We recruited Japanese residents (241,159 individuals; mean 63 years; male, 38.6 %) who had not experienced CVD event (cardiac disease or stroke, or both). We calculated estimated GFR using two equations, and compared their predictive value for first symptomatic CVD event within 1 year.

Results: Of all subjects, the mean GFR estimated by the Japanese GFR equation (JPN-eGFR) modified for Japanese was 75.83 ± 16.18 mL/min/1.73 m(2), and that by the coefficient-modified CKD-EPI equation (mCKDEPI-eGFR) was 76.39 ± 9.61 mL/min/1.73 m(2). Area under the receiver operating characteristics curves (95 % confidence intervals) for predicting CVD event by mCKDEPI-eGFR vs. JPN-eGFR were 0.596 (0.589-0.603) vs. 0.562 (0.554-0.569). Using mCKDEPI-eGFR, the crude odds ratio (OR) for CVD incident in the 4th quartile group was far more than double (OR 2.46, 95 % CI 2.29-2.66) that in the 1st quartile group. Using JPN-eGFR, the crude OR in the 4th quartile group was less than double (OR 1.61, 95 % CI 1.51-1.73) that in the 1st quartile group. However, such superior predictive value of mCKDEPI-eGFR disappeared after adjustment for confounding factors (age, gender, BMI, presence of proteinuria, hypertension, diabetes, dyslipidemia and current smoking).

Conclusion: GFR estimated by the coefficient-modified CKD-EPI equation was more closely related to CVD incidence than that estimated by the Japanese GFR equation. However, it is possible that low mCKDEPI-eGFR also reflects some cardiovascular risk(s) other than kidney dysfunction.