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How the prevalence of CKD in the US changes using age-adjusted CKD classification

Switching from the current KDIGO classification system to an age-adjusted CNI classification system increases the prevalence of CNI among younger adults and decreases it among older adults in the United States. Researchers reported the paradigm-shifting findings at Kidney Week 2022, the annual meeting of the American Society of Nephrology.

According to current KDIGO guidelines, CKD is defined as an estimated glomerular filtration rate (eGFR) of less than 60 ml/min/1.73 m22 based on the race-free 2021 CKD-EPI comparison or a urinary albumin-to-creatinine ratio (UACR) of 30 mg/g or greater. Of the 31.1 million individuals in the United States who have CKD according to the KDIGO definition, 39.4% are between the ages of 18 and under 40, 43.4% are between 40-65, and 17.2% are over 65 year. Among KDIGO, the median age in each stage of CKD is higher: 71 years for G3A, 76 years for G3B, 78 years for G4, and 63 years for G5. The researchers used 2017-2020 data from 8,016 participants in the National Health and Nutrition Examination Survey (NHANES).

According to an age-adjusted CKD classification system, CKD is defined as an eGFR of less than 75 ml/min/1.73 m2 for adults aged 18 to under 40, less than 60 ml/min/1.73 m2 for persons aged 40 to 65, or less than 45 ml/min/1.73 m2 for people over age 65, or a UACR of 30 mg/g or more, Kamyar Kalantar-Zadeh, MD, PhD, of the University of California Irvine, reported for his team. The age-dependent classification takes into account physiological age-related decline in GFR. For each age group, the respective eGFR threshold indicates the point at which the risk of death increases.


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Using the CKD age classification, 5.2 million (16.7%) of those with CKD were reclassified to no CKD according to KDIGO criteria, Dr. Kalantar-Zadeh. An additional 1.2 million (0.6%) of those without CKD under KDIGO were reclassified to CKD using the age-adjusted definitions.

“I believe that KDIGO classifications of CKD and its stages should be abandoned in real patient care,” said Dr. Kalantar-Zadeh in an interview with Kidney and Urology News. “Age-based CKD classification may prevent overdiagnosis of CKD in older individuals and identify younger individuals with low eGFR who are at risk for renal failure, thereby prioritizing care.”

He added that the CKD-EPI equations promoted by KDIGO should not replace the Cockcroft-Gault equation for dosing chemotherapy, antibiotics and other drugs, given the likely errors that could seriously affect patient safety.

dr. Kalantar-Zadeh acknowledged that the prevalence of CKD in the US is likely to change significantly once GFR is accurately measured rather than estimated.

References

Tio MC, Syed, Aliba, Streja E, et al. Changes in CKD prevalence in the United States using the age-adjusted CKD classification system. Presented at: Kidney Week; November 3-6, 2022. Summary: FR-OR24.

Delanaye P, Jager KJ, Bokenkamp A, et al. CKD: A call for an age-adjusted definition. J Am Soc Nephrol. 2019 Oct;30(10):1785-1805. doi:10.1681/ASN.2019030238

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