CKD: A Call for an Age-Adapted Definition

Abstract

Current criteria for the diagnosis of CKD in adults include persistent signs of kidney damage, such as increased urine albumin-to-creatinine ratio or a GFR below the threshold of 60 ml/min per 1.73 m2. This threshold has important caveats because it does not separate kidney disease from kidney aging, and therefore does not hold for all ages. In an extensive review of the literature, we found that GFR declines with healthy aging without any overt signs of compensation (such as elevated single-nephron GFR) or kidney damage. Older living kidney donors, who are carefully selected based on good health, have a lower predonation GFR compared with younger donors. Furthermore, the results from the large meta-analyses conducted by the CKD Prognosis Consortium and from numerous other studies indicate that the GFR threshold above which the risk of mortality is increased is not consistent across all ages. Among younger persons, mortality is increased at GFR <75 ml/min per 1.73 m2, whereas in elderly people it is increased at levels <45 ml/min per 1.73 m2. Therefore, we suggest that amending the CKD definition to include age-specific thresholds for GFR. The implications of an updated definition are far reaching. Having fewer healthy elderly individuals diagnosed with CKD could help reduce inappropriate care and its associated adverse effects. Global prevalence estimates for CKD would be substantially reduced. Also, using an age-specific threshold for younger persons might lead to earlier identification of CKD onset for such individuals, at a point when progressive kidney damage may still be preventable.

Longitudinal Changes in Kidney Function Estimated from Cystatin C and Its Association with Mortality in Elderly Women

“…A specific age-adjusted definition, with a lowering of the threshold to 45 mL/min/1.73 m 2 in patients aged 65 years and older, has been suggested [13]. Our observations support that at least in the oldest old, an age-adapted CKD classification could be of value to avoid overdiagnosis of CKD and, in addition, avoid unnecessary psychological cost to the patient.…”

“…Given this apparent age dependency, there is an ongoing discussion about the clinical implications of age-related decline in kidney function [6,[11][12][13]. Existing KDI-GO definition and therapy recommendations do not take age into consideration -an eGFR <60 mL/min/1.73 m 2 equates to CKD, be the patient 25 or 105 years old.…”

Proteinuria in COVID-19: prevalence, characterization and prognostic role

“…A clear distinction between chronic kidney disease (CKD) and acute kidney injury (AKI) is not always possible. Therefore, we used the term "decreased kidney function", based on the CKD-Epidemiology equation and using an age-calibrated de nition: estimated glomerular ltration rate (eGFR) below 75, 60 or 45 mL/min/1.73m 2 for patients younger than 40 years, between 40 and 65 years or older than 65 years, respectively [12,13]. Because proteinuria and hematuria can be in uenced by CKD status and/or AKI, analyses were repeated in subgroups without decreased eGFR at D0.…”

Symmetric Dimethylarginine as a Secondary Prevention Biomarker of Chronic Kidney Disease

“…Serum SDMA yet increases earlier than Cr, as the GFR decreases in experimental CKD, by a mean of 9.8 months (range, 2.2-27.0 months) [5], thus allowing for timely detection of mild kidney dysfunction. Furthermore, SDMA has the advantage of not being influenced by nonrenal factors that are proven to influence Cr and/ or cystatin C, such as lean body mass, food intake, inflammation, diabetes, and estrogen therapy [4].There is a continuing debate about an age-adjusted definition of CKD [6]. A recent trial suggested a potential of targeted metabolomics that includes SDMA (also citrulline, Cr, and S-adenosylmethionine) to address agerelated changes in early CKD using principal component analysis [7], at least in the pediatric population.…”

“…There is a continuing debate about an age-adjusted definition of CKD [6]. A recent trial suggested a potential of targeted metabolomics that includes SDMA (also citrulline, Cr, and S-adenosylmethionine) to address agerelated changes in early CKD using principal component analysis [7], at least in the pediatric population.…”