Revised equations for estimated GFR from serum creatinine in Japan

Am J Kidney Dis. 2009 Jun;53(6):982-92. doi: 10.1053/j.ajkd.2008.12.034. Epub 2009 Apr 1.


Background: Estimation of glomerular filtration rate (GFR) is limited by differences in creatinine generation among ethnicities. Our previously reported GFR-estimating equations for Japanese had limitations because all participants had a GFR less than 90 mL/min/1.73 m2 and serum creatinine was assayed in different laboratories.

Study design: Diagnostic test study using a prospective cross-sectional design. New equations were developed in 413 participants and validated in 350 participants. All samples were assayed in a central laboratory.

Setting & participants: Hospitalized Japanese patients in 80 medical centers. Patients had not participated in the previous study.

Reference test: Measured GFR (mGFR) computed from inulin clearance.

Index test: Estimated GFR (eGFR) by using the modified isotope dilution mass spectrometry (IDMS)-traceable 4-variable Modification of Diet in Renal Disease (MDRD) Study equation using the previous Japanese Society of Nephrology Chronic Kidney Disease Initiative (JSN-CKDI) coefficient of 0.741 (equation 1), the previous JSN-CKDI equation (equation 2), and new equations derived in the development data set: modified MDRD Study using a new Japanese coefficient (equation 3), and a 3-variable Japanese equation (equation 4).

Measurements: Performance of equations was assessed by means of bias (eGFR - mGFR), accuracy (percentage of estimates within 15% or 30% of mGFR), root mean squared error, and correlation coefficient.

Results: In the development data set, the new Japanese coefficient was 0.808 (95% confidence interval, 0.728 to 0.829) for the IDMS-MDRD Study equation (equation 3), and the 3-variable Japanese equation (equation 4) was eGFR (mL/min/1.73 m2) = 194 x Serum creatinine(-1.094) x Age(-0.287) x 0.739 (if female). In the validation data set, bias was -1.3 +/- 19.4 versus -5.9 +/- 19.0 mL/min/1.73 m2 (P = 0.002), and accuracy within 30% of mGFR was 73% versus 72% (P = 0.6) for equation 3 versus equation 1 and -2.1 +/- 19.0 versus -7.9 +/- 18.7 mL/min/1.73 m(2) (P < 0.001) and 75% versus 73% (P = 0.06) for equation 4 versus equation 2 (P = 0.06), respectively.

Limitation: Most study participants had chronic kidney disease, and some may have had changing GFRs.

Conclusion: The new Japanese coefficient for the modified IDMS-MDRD Study equation and the new Japanese equation are more accurate for the Japanese population than the previously reported equations.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Creatinine / blood*
  • Cross-Sectional Studies
  • Female
  • Glomerular Filtration Rate / physiology*
  • Humans
  • Japan / epidemiology
  • Japan / ethnology
  • Kidney Diseases / epidemiology*
  • Kidney Diseases / ethnology
  • Kidney Diseases / physiopathology*
  • Kidney Function Tests / methods
  • Kidney Function Tests / standards
  • Male
  • Middle Aged
  • Prospective Studies
  • Reproducibility of Results


  • Creatinine