Predictors and reference equations for augmentation index, an arterial stiffness marker, in healthy children and adolescents

OBJECTIVES: To investigate predictors and propose reference equations for the augmentation index normalized to 75 bpm heart rate (AIx@75) in healthy children and adolescents. METHODS: This was a cross-sectional, observational study involving 134 healthy children and adolescents aged 9 to 19 years old. Participants were categorized into child (n=53) and adolescent (n=81) groups, as well as into male (n=69) and female (n=65) groups. We evaluated AIx@75, vascular and hemodynamic parameters, anthropometric data, physical activity profile, and quality of life (Peds-QL4.0; physical, emotional, social and school domains). RESULTS: The predictors of AIx@75 in the whole sample were age, peripheral diastolic blood pressure (pDBP), mean arterial pressure, pulse pressure amplification (PPA), systolic volume (SV), cardiac index (CI), and pulse wave velocity (PWV; R2=80.47%). In the male group, the predictors of AIx@75 were SV, CI, total vascular resistence (TVR), and PWV (R2=78.56%), while in the female group, they were pDBP, PPA, SV, and PWV (R2=82.45%). In the children, they were pDBP, PPA, SV, and PWV (R2=79.17%), while in the adolescents, they were body mass index, pDBP, PPA, SV, TVR, and PWV (R2=81.57%). CONCLUSION: In the present study, we used a representative sample from Belo Horizonte to establish normality values of AIx@75. We also identified, for the first time, independent predictors of AIx@75 in healthy children and adolescents categorized by sex and age. Determining AIx@75 reference equations may facilitate the early diagnosis of preclinical atherosclerosis and allow an objective measure of the vascular effects of therapeutic interventions aimed at modifying cardiovascular risk factors.