Kidney Health and Longevity: The Organ That Predicts Your Cardiovascular Future
Chronic kidney disease (CKD) is common and usually silent: in US national surveys, its prevalence among adults rose from 10.0% in 1988 to 1994 to 13.1% in 1999 to 2004.1 It can be found with two routine tests, eGFR and the urine albumin-to-creatinine ratio (uACR), and lower eGFR and higher albuminuria are each linked to higher mortality.2,5
- CKD is staged by two measures: glomerular filtration rate, usually estimated from a blood test (eGFR), and albuminuria, measured as the urine albumin-to-creatinine ratio (uACR).2
- In general population cohorts with 105,872 people, the risk of death rose steadily with urine albumin, with no threshold, and rose as eGFR fell below about 75.5
- Heart and kidney disease feed each other: failing function in one organ can trigger dysfunction in the other, a pattern called cardiorenal syndrome.3
- In the DAPA-CKD trial of 4,304 people with CKD, with or without type 2 diabetes, dapagliflozin cut the combined risk of major eGFR decline, kidney failure or death from kidney or heart causes from 14.5% to 9.2% over a median of 2.4 years.4
- The eGFR equations published in 2021 no longer use race, and the equations that combine creatinine with cystatin C were the most accurate.6
The kidneys filter waste from the blood and help regulate blood pressure, fluid and electrolyte balance, red blood cell production and vitamin D activation. Chronic kidney disease is a general term for disorders affecting kidney structure and function,2 and in the US its prevalence among adults rose from 10.0% in 1988 to 1994 to 13.1% in 1999 to 2004.1
The Two Diagnostic Pillars: eGFR and uACR
Chronic kidney disease is staged using two markers: glomerular filtration rate (GFR), which reflects how well the kidneys filter blood, and albuminuria, which reflects kidney damage. Both can be checked with routine laboratory tests.2 GFR is usually estimated from blood tests: the CKD-EPI equations published in 2021 calculate it from creatinine, cystatin C or both, without race, and the equations that combine creatinine with cystatin C were the most accurate.6 You can estimate yours with our eGFR calculator.
The urine albumin-to-creatinine ratio (uACR) measures albumin leaking into the urine. In a meta-analysis of general population cohorts with 105,872 people, the risk of death rose steadily with higher uACR, with no threshold below which it stopped mattering. For eGFR, risk was flat between 75 and 105 and rose below that: compared with an eGFR of 95, the adjusted hazard ratio for death was 1.18 at 60, 1.57 at 45 and 3.14 at 15.5
The Cardiorenal Connection
The relationship between kidney and heart disease runs both ways. Cardiorenal syndrome describes how acute or chronic dysfunction of the heart or kidneys can induce dysfunction in the other organ; chronic heart failure, for example, can cause progressive chronic kidney disease.3
SGLT2 Inhibitors: What DAPA-CKD Showed
The DAPA-CKD trial randomized 4,304 people with an eGFR of 25 to 75 and a uACR of 200 to 5,000 mg/g, with or without type 2 diabetes, to dapagliflozin 10 mg daily or placebo. It was stopped early for efficacy: over a median of 2.4 years, the combined outcome of a sustained eGFR decline of at least 50%, end-stage kidney disease, or death from kidney or cardiovascular causes occurred in 9.2% of the dapagliflozin group and 14.5% of the placebo group, so 19 people needed treatment to prevent one event.4
Practical Steps
Because CKD is silent, the practical step is testing: eGFR and uACR come from routine laboratory tests, and once CKD is found, treatments can slow its progression and reduce cardiovascular risk.2 If your results are abnormal, review your blood pressure, blood sugar, medicines that can affect the kidneys (such as regular use of anti-inflammatory painkillers) and diet with a clinician.
Put this research into practice: Biomarker Reference Tool · Lab Results Interpreter
References
- 1Coresh J, et al. "Prevalence of chronic kidney disease in the United States." JAMA. 2007;298(17):2038-47. PubMed · DOI
- 2Levey AS, Coresh J. "Chronic kidney disease." Lancet. 2012;379(9811):165-80. PubMed · DOI
- 3Ronco C, et al. "Cardiorenal syndrome." J Am Coll Cardiol. 2008;52(19):1527-39. PubMed · DOI
- 4Heerspink HJL, et al. "Dapagliflozin in Patients with Chronic Kidney Disease." N Engl J Med. 2020;383(15):1436-1446. PubMed · DOI
- 5Matsushita K, et al. "Association of estimated glomerular filtration rate and albuminuria with all-cause and cardiovascular mortality in general population cohorts: a collaborative meta-analysis." Lancet. 2010;375(9731):2073-81. PubMed · DOI
- 6Inker LA, et al. "New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race." N Engl J Med. 2021;385(19):1737-1749. PubMed · DOI
