Ambulatory arterial stiffness index among children and adolescents with chronic kidney disease: a report from the Chronic Kidney Disease in Children Study.
BACKGROUND To quantify the association between ambulatory arterial stiffness index (AASI) and hypertensive status, and to identify additional predictors of AASI, including body mass index (BMI), proteinuria, and mineral metabolism, in children and adolescents with chronic kidney disease (CKD). METHODS We analyzed data collected from 654 participants during 1283 study visits in the Chronic Kidney Disease in Children (CKiD) prospective cohort study. AASI was calculated from ambulatory blood pressure monitoring (ABPM) data as 1 minus the slope coefficient from a least squares linear regression of diastolic blood pressure (BP) on systolic BP. Hypertensive status was determined by clinic BP and ABPM. Linear regression with generalized estimating equations to account for repeated AASI measurements over time within the same participant were used to quantify the relationship between AASI and hypertensive status. RESULTS At their first successful ABPM visit, the median age was 12 years, 61% were male, 15% had obesity and the median eGFR was 49 ml/min/1.73 m2. Over half (57%) reported current antihypertensive therapy use with RAAS inhibitors, yet 42% met criteria for abnormal ABPM (elevated mean total/awake/sleep DBP/SBP per updated guidelines). Masked hypertension (MH) was common (27%) and associated with significantly higher AASI compared to being normotensive (difference in mean AASI: + 0.051, 95% CI: 0.032, 0.071). Male sex and higher BMI were associated with higher AASI, but the presence of proteinuria, abnormal serum calcium or phosphate were not. CONCLUSION AASI is associated with MH and BMI in children and adolescents with CKD and may be a useful non-invasive measure of vascular stiffness in this population.