Performance and Determinants of Serum Creatinine and Cystatin C–Based GFR Estimating Equations in South Asians

Yeli Wang, Andrew S. Levey, Lesley A. Inker, Saleem Jessani, Rasool Bux, Zainab Samad, Ali Raza Khan, Amy B. Karger, John C. Allen, Tazeen H. Jafar

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11 Citations (Scopus)

Abstract

Introduction: The creatinine-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate (eGFR) equation was calibrated for the general Pakistan population (eGFRcr-PK) to eliminate bias and improve accuracy. Cystatin C–based CKD-EPI equations (eGFRcys and eGFRcr-cys) have not been assessed in this population, and non-GFR determinants of cystatin C are unknown. Methods: We assessed eGFRcys, eGFRcr-cys, and non-GFR determinants of cystatin C in a cross-sectional study of 557 participants (≥40 years of age) from Pakistan. We compared bias (median difference in measured GFR [mGFR] and eGFR), precision (interquartile range [IQR] of differences), accuracy (percentage of eGFR within 30% of mGFR), root mean square error (RMSE), and classification of mGFR <60 ml/min/1.73 m2 (area under the receiver operating characteristic curve [AUC] and net reclassification index [NRI]) among eGFR equations. Results: We found that eGFRcys underestimated mGFR (bias, 12.7 ml/min/1.73 m2 [95% confidence interval {CI} 10.7–15.2]). eGFRcr-cys did not improve performance over eGFRcr-PK in precision (P = 0.52), accuracy (P = 0.58), or RMSE (P = 0.49). Results were consistent among subgroups by age, sex, smoking, body mass index (BMI), and eGFR. NRI was 7.31% (95% CI 1.52%–13.1%; P < 0.001) for eGFRcr-cys versus eGFRcr-PK, but AUC was not improved (0.92 [95% CI 0.87–0.96] vs. 0.90 [95% CI 0.86–0.95]; P = 0.056). Non-GFR determinants of higher cystatin C included male sex, smoking, higher BMI and total body fat, and lower lean body mass. Conclusion: eGFRcys underestimated mGFR in South Asians and eGFRcr-cys did not offer substantial advantage compared with eGFRcr-PK. Future studies are warranted to better understand the large bias in eGFRcys and non-GFR determinants of cystatin C in South Asians.

Original languageEnglish
Pages (from-to)962-975
Number of pages14
JournalKidney International Reports
Volume6
Issue number4
DOIs
Publication statusPublished - Apr 2021

Keywords

  • Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)
  • South Asian
  • cystatin C
  • estimating equations
  • glomerular filtration rate (GFR)
  • kidney function

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