Arterial Stiffness and Renal Outcomes

CKD is estimated to affect more than 850 million people worldwide and constitutes a major risk factor for cardiovascular disease and mortality, making it a pressing global public health problem.1 Therefore, early identification of individuals at risk for kidney function decline and timely preventive interventions are of paramount importance. While hypertension, diabetes, and dyslipidemia have long been recognized as major drivers of CKD progression, large artery stiffness (LAS) is increasingly recognized as an independent predictor of adverse renal outcomes. In Western populations, carotid–femoral pulse wave velocity (cfPWV) has been established as the reference standard for assessing LAS. cfPWV is strongly dependent on aortic wall stiffness, but requires exposure of the carotid and femoral sites, as well as technical expertise, limiting its feasibility in everyday clinical practice. In East Asia, brachial–ankle pulse wave velocity (baPWV), which reflects integrated stiffness of both central and peripheral arteries, has been widely used in clinical and epidemiological studies. baPWV can be measured easily and noninvasively using automated oscillometric devices. Several reports have linked baPWV to kidney function decline, but its long-term prognostic value for renal outcomes in US populations had not been thoroughly investigated. In this issue of Kidney360, Ledet et al. measured baseline baPWV among 1862 participants who referred to the Mayo Clinic Cardiovascular Health Clinic for cardiovascular disease screening by exercise electrocardiogram between 2007 and 2009 and followed them for a median of 13.2 years.2 They demonstrated that each 1-SD increase in baPWV was independently associated with a significantly faster annual decline in eGFR (−0.18 ml/min per 1.73 m2 per year), even after adjustment for baseline kidney function and cardiovascular risk factors. Moreover, individuals in the highest baPWV category had a 2.4-fold higher risk of incident CKD (95% confidence interval, 1.1 to 5.4) compared with those in the normal category. These findings support the potential value of baPWV as a simple, clinically applicable tool to aid in the prediction of long-term kidney outcomes. These results should be interpreted in the context of prior studies. In Japan, Tomiyama et al. assessed baPWV in a cohort of 2053 middle-aged workers and followed them for an average of 5–6 years.3 They found that higher baseline baPWV predicted a faster decline in eGFR and a higher incidence of new-onset CKD, while baseline kidney function did not predict subsequent changes in baPWV, supporting a primarily unidirectional longitudinal relationship of arterial stiffness on renal decline. By contrast, in the United States, the Atherosclerosis Risk in Communities study, a community-based investigation of adults aged 40 years or older, evaluated several arterial stiffness indices in a cross-sectional design.4 In this study, cfPWV and heart–femoral and heart–ankle pulse wave velocity (PWV) were more closely associated with impaired kidney function and prevalent CKD, compared with baPWV, which showed only modest associations, leaving uncertainty about its association with future kidney dysfunction in US populations. In this context, the study by Ledet et al. is novel in filling this important gap. By applying baPWV in a US cohort and implementing long-term follow-up, the investigators demonstrated that baPWV independently predicted the rate of kidney function decline and the risk of incident CKD. The dual presentation of continuous effect sizes and categorical hazard ratios further strengthens the clinical interpretability of their findings. Several limitations merit consideration. The study population consisted of a clinical referral population predominantly composed of White men, limiting generalizability across racial and sex groups, or unselected community-based samples. Prior research by Kime et al. suggested that the relationship between arterial stiffness and renal function differs by sex, with stronger associations observed in men and potential modifying effects of menopausal status in women.5 Thus, sex-specific differences in the vascular–renal axis may be clinically important and require further study in diverse populations. In addition, baPWV was measured only once, precluding evaluation of longitudinal changes or the effects of therapeutic interventions. Kidney function was estimated from serum creatinine, without cystatin C or direct GFR measurements, and albuminuria was not analyzed as a continuous outcome. Owing to the retrospective nature of the study, baseline eGFR estimations were done by convenience, depending on the availability of creatinine measurements around the time of the baPWV measurements, introducing heterogeneity. Similarly, prospective systematic periodic measurements of eGFR were not performed, but depended on availability of creatinine levels, presumably derived predominantly from clinical care. Finally, baPWV includes long muscular arterial segments, and it is thus less specific for large arterial properties compared with cfPWV. Thus, results based on one measure cannot be assumed to generalize to the other.6 Finally, the magnitude of the standardized estimate describing the relationship between baseline baPWV and renal function decline is modest. Although the association seemed to be steeper among participants with baseline eGFRCr ≥90 ml/min per 1.73 m2, these results are difficult to interpret, because of the lack of formal statistical interaction testing and to the likely influence of regression to the mean, as pointed out by the authors. Finally, although Ledet et al. did not directly address mechanisms, prior work provides a conceptual framework (Figure 1).7 The kidney is a high-flow, low-resistance organ because it receives a large share of cardiac output per gram of tissue, by virtue of maintaining a very low vascular resistance, a profile that makes the glomerular microcirculation highly vulnerable to pulsatile stress. As LAS increases, the buffering function of the aorta diminishes and excessive pulsatile energy reaches the renal microvasculature. This phenomenon is believed to contribute to glomerular hypertension, structural injury, albuminuria, and progressive decline in filtration. Safar et al. demonstrated that LAS is associated with renal impairment independently of mean arterial pressure, highlighting the causal role of vascular properties themselves.8 They also demonstrated that persistently high cf-PWV in dialysis patients predicts poor survival despite BP control. These observations support the concept that LAS, rather than BP alone, represents a critical predictor of renal outcomes in advanced CKD.Figure 1: Vascular and renal functions are tightly interrelated, mutually influencing one another and perpetuating a vicious cycle. LAS, large artery stiffness; RAAS, renin-angiotensin-aldosterone system.Conversely, kidney dysfunction accelerates vascular stiffening through multiple pathways. CKD is characterized by disordered bone mineral metabolism, with elevated fibroblast growth factor-23 and osteoprotegerin promoting vascular calcification. Uremic toxins induce oxidative stress and inflammation, leading to phenotypic changes in vascular smooth muscle cells and extracellular matrix remodeling. Chronic increases in inflammatory mediators, such as TGF-β, C-reactive protein, TNF-α, and interleukin-6 further drive arterial damage. Impaired sodium excretion, overactivation of the renin-angiotensin-aldosterone system, and heightened sympathetic activity promote collagen deposition and smooth muscle hypertrophy. Together, these processes create a vicious cycle: stiff arteries damage the kidney and declining kidney function further accelerates arterial stiffening. The clinical consequences of this vascular–renal interplay are important and extend beyond the kidney. In the Chronic Renal Insufficiency Cohort study, higher cfPWV independently predicted hospitalization for heart failure, progression to ESKD, and all-cause mortality.9 Similarly, in French dialysis cohorts, patients with persistently elevated PWV despite antihypertensive treatment had dramatically poorer overall survival.10 In conclusion, the study by Ledet et al. provides novel evidence that baPWV is independently associated with accelerated decline in kidney function, higher risk of incident CKD, and shorter CKD-free survival over long-term follow-up in a US population. By extending evidence from East Asian populations, this work highlights the potential clinical utility of a simple and reproducible measure of arterial stiffness and reinforces the broader concept of the vascular–renal axis. As CKD prevalence continues to rise globally, integrating vascular assessments into risk prediction and developing interventions that target arterial stiffness represent urgent priorities for improving kidney and cardiovascular outcomes.