Kidney Week

Abstract: TH-OR61

Quantifying Individual-Level Uncertainty in GFR Estimation

Session Information

• Preventing Progression and Reassessing Race in GFR Estimation
  November 04, 2021 | Location: Simulive, Virtual Only
  Abstract Time: 04:30 PM - 06:00 PM

Category: CKD (Non-Dialysis)

• 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

• Zhu, Xiaoqian, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Xiaoqian Zhu, PhD

• Lirette, Seth, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Seth Lirette,

• Rule, Andrew D., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Andrew D. Rule,

• Mosley, Tom, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Tom Mosley,

• Butler, Kenneth R., The University of Mississippi Medical Center, Jackson, Mississippi, United States

Kenneth R. Butler,

• Butler, Javed, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Javed Butler,

• Hall, Michael, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Michael Hall,

• Vaitla, Pradeep, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Pradeep Vaitla,

• Wynn, James J., The University of Mississippi Medical Center, Jackson, Mississippi, United States

James J. Wynn,

• Dossabhoy, Neville R., The University of Mississippi Medical Center, Jackson, Mississippi, United States

Neville R. Dossabhoy,

• Guallar, Eliseo, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States

Eliseo Guallar,

• Shafi, Tariq, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Tariq Shafi,

Background

Although the differences between estimated GFR (eGFR) and measured GFR (mGFR) are well-recognized, the magnitude and potential clinical implications of these differences at the individual level are not fully appreciated.

Methods

Using data from four US community-based cohorts with mGFR (total N=3,223), we calculated eGFR from serum creatinine alone (eGFR_CR) and cystatin and creatinine (eGFR_CYS-CR) using the CKD-EPI equations without race coefficients. Using quantile regression, we assessed eGFR's individual-level reliability by calculating a 95% prediction interval (PI), defined as the distribution of 95% of the observed mGFR values at a given eGFR. We also assessed eGFR's population-level reliability using standard metrics, including median difference (eGFR-mGFR). All GFR results are presented as ml/min/1.73m².

Results

The participants' median age was 61 years, 32% were Black, and 55% were female. The median mGFR was 68 (IQR, 46 to 88). At the population level, the median difference between eGFR_CR and mGFR was small (1.4; 95% CI: 0.9 to 1.9). In contrast, the individual-level 95% PI of the eGFR_CR was large, ranging from 53 to 120 at eGFR_CR 90 and from 19 to 55 at eGFR_CR 30 (Figure and Table). Substantial individual misclassification was also noted using eGFR_CR; 16% of individuals with eGFR_CR <60 and 28% of those with eGFR_CR <30 had mGFR above those thresholds. Results were similar for eGFR_CYS-CR.

Conclusion

A substantial individual-level discrepancy exists between eGFR and mGFR. The eGFR PI should be included with eGFR reporting. Some clinical decisions may need to be based on mGFR rather than eGFR.

Table 1

Funding

• Other NIH Support