Background: The Modification of Diet in Renal Disease (MDRD) equation is often used to determine an estimated glomerular filtration rate (eGFR) from serum creatinine. This study compared kidney disease as defined by reduced eGFR, elevated serum creatinine, or elevated urinary albumin-to-creatinine ratio (ACR).
Methods: As part of the Genetic Epidemiology Network of Arteriopathy study, a community-based sample was ascertained through sibships having at least two members with essential hypertension. Kidney disease was defined by reduced eGFR (<60 mL/min/1.73 m(2)), elevated serum creatinine (>97.5(th) percentile for sex-specific normal individuals), or elevated ACR (>95(th) percentile for sex-specific normal individuals).
Results: The sample (n = 2653) was 65% female, 61% African American, and 77% hypertensive, with a mean (+/- SD) age of 61 +/- 10 years. There was greater agreement between kidney disease defined by elevated ACR and an elevated serum creatinine level (kappa = 0.19) than between kidney disease defined by elevated ACR and a reduced eGFR (kappa = 0.07). The multivariable-adjusted odds ratio of kidney disease for male versus female sex was 0.92 (95% CI, 0.75 to 1.12) by reduced eGFR, but was 2.08 (95% CI, 1.62 to 2.67) by elevated serum creatinine and 2.11 (95% CI, 1.63 to 2.74) by elevated ACR. The multivariable-adjusted odds ratio of kidney disease for subjects of African American versus white ethnicity was 0.27 (95% CI, 0.22 to 0.33) by reduced eGFR but was 1.17 (95% CI, 0.91 to 1.51) by elevated serum creatinine and 3.87 (95% CI, 2.89 to 5.25) by elevated ACR.
Conclusion: In a predominantly hypertensive population, kidney disease identified by elevated ACR was more concordant with elevated serum creatinine than with reduced eGFR. The MDRD equation, derived using kidney disease patients, may misrepresent the gender- and ethnicity-specific risk of kidney disease.