Kidney Week

Abstract: TH-PO879

Changes in CKD Prevalence With and Without eGFR Indexing to the Median Body Surface Area in the United States

Session Information

• CKD: Epidemiology, Risk Factors, Prevention - I
  November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 2201 CKD (Non-Dialysis): Epidemiology‚ Risk Factors‚ and Prevention

Authors

• Streja, Elani, University of California Irvine, Irvine, California, United States

Elani Streja,

• Tio, Maria Clarissa, University of Mississippi Medical Center, Jackson, Mississippi, United States

Maria Clarissa Tio,

• Syed, Aliba, University of California Irvine, Irvine, California, United States

Aliba Syed,

• Obi, Yoshitsugu, University of Mississippi Medical Center, Jackson, Mississippi, United States

Yoshitsugu Obi,

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

Michael Hall,

• Kalantar-Zadeh, Kamyar, University of California Irvine, Irvine, California, United States

Kamyar Kalantar-Zadeh,

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

Tariq Shafi,

Background

The eGFR is reported indexed to a body surface area (BSA) of 1.73m², the estimated BSA of 25-year-olds in 1912. However, the contemporary median BSA of the US population is higher than 1.73 and arbitrarily indexing eGFR to a lower BSA may systematically overcalculate CKD prevalence, particularly Stage G3A A1. We assessed the changes in the U.S. CKD prevalence using eGFR indexed to the median BSA of the U.S. population (ml/min/medianBSA), with particular emphasis on CKD G3A.

Methods

We analyzed the 2017-2020 National Health and Nutrition Examination Survey (NHANES; N=8,016). eGFR was calculated using the CKD-EPI 2021 race-free equation while individual BSA was calculated from the DuBois & DuBois formula. We used reclassification tables to determine the changes in CKD prevalence when eGFR is indexed to 1.73m² (eGFR/1.73) vs. indexed to median BSA in the US (eGFR/Median). We defined CKD as eGFR <60 or ACR ≥30 mg/g.

Results

The median US BSA was 1.91m² (2.0m² in males and 1.78m² in females). The BSA of 1.73 corresponded to the 26th percentile for the US population (6.4^th percentile in males and 39.6^th percentile in females). The median eGFRs of the US population was 108 ml/min/1.73m² and 109.2 ml/min/1.91m². Using eGFR/Median instead of eGFR/1.73, 3.7 million (12%) US adults with CKD (eGFR<60 mL/min/1.73m² or ACR ≥30 mg/g) were no longer classified as CKD (Table 1). All of those reclassified as no CKD were in CKD 3a A1 (ACR <30) and comprised 54% of the US population with CKD 3a A1.

Conclusion

Our data suggest overdiagnosis of CKD using only eGFR with arbitrary selection of BSA-indexing to 1.73m² and that using the outdated BSA for eGFR indexing leads to an 11.8% higher CKD prevalence in the US.

Funding

• Other NIH Support