Assessment of creatinine and cystatin C-based eGFR equations in Chinese older adults with chronic kidney disease.

Background: Glomerular filtration rate (GFR) estimation equations using creatinine and Cystatin-C appear to be superior to those based on creatinine or Cystatin-C in older adults. We sought to compare the performances of those based on creatinine and Cystatin-C in Chinese older adults with chronic kidney disease (CKD).

Methods: A total of 368 Chinese elderly with CKD underwent the dynamic imaging with technetium-99m diethylene-triamine-pentaacetic acid (99mTc-DTPA), and serum creatinine and Cystatin-C were measured on the same day. The comparison of GFR equations which were creatinine and Cystatin-C-based including chronic kidney disease epidemiology collaboration (CKD-EPI) equation (CKD-EPI-Cr-Cys), Berlin Initiative Study (BIS) equation (BIS-Cr-Cys, also known as BIS-2), MA equation (MA-Cr-Cys), and FENG equation (FENG-Cr-Cys) was conducted.

Results: Four equations overestimated GFR except for BIS-2 equation in mGFR ≥ 60 ml/min/1.73 m2 (bias: - 1.40, p = 0.7) and CKD-EPI-Cr-Cys equation in mGFR < 30 ml/min/1.73 m2 (bias: - 1.82, p = 0.2) were unbiased. BIS-2 equation had the smallest interquartile range (IQR, ml/min/1.73 m2) from 12.73 in age < 75 years group to 16.05 in age ≥ 75 years group. BIS-2 equation achieved highest values of 79.1% in overall participants, and 80.77% in age ≥ 75 years group, respectively, and CKD-EPI-Cr-Cys equation 82.26% in age < 75 years group. Lowest values of root-mean-square error (RMSE, ml/min/1.73 m2) were seen in BIS-2 equation from 13.22 in age < 75 years group to 16.18 in age ≥ 75 years group. BIS-2 equation had the lowest misclassification rates of 41.76% in age ≥ 75 years group and 34.41% in age < 75 years group.

Conclusions: BIS-2 equation may be optimal for Chinese older adults with CKD especially in older adults ≥ 75 years and with mGFR ≥ 30 ml/min/1.73 m2, while CKD-EPI-Cr-Cys equation could yield a better performance than BIS-2 equation, especially in those < 75 years and mGFR < 30 ml/min/1.73 m2.