Digital microvascular reactivity does not decline with impaired renal function in chronic kidney disease

BACKGROUND: The reactive hyperemia index (RHI), measured by peripheral arterial tonometry (PAT), is a novel measurement of endothelial function and has been proven to be valuable in cardiovascular risk stratification in several populations. The current study aims to explore its relation to renal function and its association with traditional cardiovascular risk factors in patients with chronic kidney disease (CKD). METHODS: Subjects with non-dialysis dependent CKD were recruited and 252 of them had a successful PAT test. In addition to general demographic and medical information, carotid-femoral pulse wave velocity (cfPWV), carotid-radial pulse wave velocity (crPWV) and augmentation index (AIx) were recorded. RESULTS: The mean age of the study population was 57.7 (±14.7) years and 155 (61.5%) were males. The average RHI was 1.92 (±14.7) with no difference noted between males and females. There was no statistically significant correlation between RHI and eGFR (r = - 0.107, p = 0.089) or urine protein-to-creatinine ratio (r = 0.036, p = 0.570). With adjustment for age and sex, RHI was associated with systolic blood pressure (BP) (β = 0.006, p = 0.001), diastolic BP (β = 0.008, p = 0.010), heart rate (β = - 0.007, p = 0.015) crPWV (β = 0.037, p = 0.022) and AIx (β = 0.006, p = 0.001), but not with cfPWV or any other conventional risk factors analyzed. Systolic BP remained the only predictor for RHI in the stepwise regression analysis. CONCLUSIONS: RHI did not decline with reduced renal function in CKD patients and had a modest association with traditional cardiovascular risk factors. Further studies are warranted to determine if RHI could predict cardiovascular outcome in CKD patients.