GFR estimation in Japan and China: what accounts for the difference?

摘要

A primary goal for staging chronic kidney disease (CKD) with glomerular filtration rate (GFR) has been to risk-stratify patients for adverse outcomes. A somewhat arbitrary threshold (<60 mL/min/1.73 m~) defines CKD and another somewhat arbitrary threshold (< 15 mL/ min/1.73 m~2) defines kidney failure. The literature based on a uniform CKD staging system supports various screening and intervention guidelines. GFR usually is estimated from serum creatinine level, age, sex, and ethnicity (African American compared with white) by using the Modification of Diet in Renal Disease (MDRD) Study equation. Notably, there have always been concerns with the ethnicity coefficient because it does not address nonwhite non-African American ethnic groups. Several studies have sought to address this problem in order to apply GFR estimation in nonwhite non-African American populations. Ma et al developed a new coefficient (1.23) that estimates a 23% greater GFR in Chinese than whites (the arbitrary reference group) at the same serum creatinine level. In this issue of the American Journal of Kidney Diseases, Matsuo et al developed a new coefficient (0.81) that estimates a 19% lower GFR in Japanese than whites at the same serum creatinine level, which is similar to a previously reported Japanese coefficient (0.76). To put these coefficients into perspective, a 60-year-old man with a serum creatinine level of 1.4 mg/dL would have an estimated GFR of 52 mL/min/1.73 m~2 if white, but 64 mL/min/1.73 m~2 if Chinese and 42 mL/min/1.73 m~2 if Japanese. What accounts for the difference?