There is a bidirectional relationship between declining kidney function and raised blood pressure, two prominent features of aging. The kidney is responsible for managing blood volume (one contribution to blood pressure) by adjusting the amount of water in blood as the bloodstream is filtered, a process that depends on some combination of the sensing of soluble factors and pressure. These complex systems fail with age in ways that can lead to raised blood pressure. Raised blood pressure in turn can damage the kidney directly, but also indirectly disrupt the balance of blood pressure control systems elsewhere in the body, such as via the constriction and dilation of blood vessels, or heart rate, that interact with those of the kidney via signaling molecules. It is a complex set of feedback loops, well-balanced in youth, but prone to damage that can cause a spiral into ever high blood pressure with advancing age.
Cardiovascular diseases affect kidney function. The aim of this study was to investigate the possible associations between hemodynamic parameters and change in kidney function in individuals aged 75 years and older. Data on hemodynamics and blood and urine samples were collected at baseline and during one-year visits. Hemodynamics were split into two groups based on median values. Changes in the estimated glomerular filtration rate (eGFR) were investigated between low and high groups for each hemodynamic parameter using analysis of variance. Changes in the albumin-creatinine ratio (ACR) were examined as binary outcomes (large increase vs. stable) using logistic regression.
The study population consisted of 252 participants. Participants in the high central systolic blood pressure (cSBP) group had a greater decline in eGFR than participants in the low cSBP group (-6.3% vs. -2.7%). Participants in the high aortic pulse wave velocity (aPWV) group, indicative of greater arterial stiffness, had a greater decline in eGFR than those in the low aPWV group (-6.8% vs. -2.5%). Other hemodynamic parameters were not associated with eGFR changes.
In conclusion, we found that elevated central aortic stiffness is associated with a greater decline in kidney function in old age. Since aPWV and cSBP both appear to be predictors of eGFR decline, it might be of interest to identify older individuals with elevated aortic stiffness. In this specific population, intensive blood pressure reduction might be justified in order to slow down the process of vascular aging and prevent kidney function decline.
Link: https://doi.org/10.3390/jcm13051334
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