Is augmentation index a good measure of vascular stiffness in the elderly?

Objectives: We investigated the exact relationship between age and gender on augmentation pressure (AG) and augmentation index (AI) measured over the radial (muscular) and carotid (elastic) arteries. Design and Methods: AG is the contribution that wave reflection makes to systolic arterial pressure. AI is an indirect measure of arterial stiffness and is calculated as AG divided by pulse pressure (PP) × 100. AG and AI both increase with age. AG and AI were measured in 458 subjects using SphygmoCor. A total of 755 readings were obtained (302 carotid, 453 radial). The mean age was 57.5 ± 13.7 years. Diabetic subjects were excluded. Among the subjects, 13.5% were hypertensive. Results: Women had mean values of AI significantly higherthan men in both radial and carotid arteries. These differences were less marked with AG. Quadratic equations better described the relationship between AI and age but not AG and age. Thus, AI increased with age up to our median age of 55 years but plateaued thereafter, whereas the AG continued to increase steadily with age. A multiple regression analysis demonstrated that both AI and AG were negatively related to height and positively related to diastolic blood pressure (DBP). Conclusions: AG continues to increase inthe elderly over the age of 55, but not AI. AI is higher in women and higher when measured over the carotid than the radial. AI is positively related to DBP and negatively to height. AG is proposed as a more suitable measure of arterial stiffness than AI. © The Author 2007. Published by Oxford University Press on behalf of the British Geriatrics Society.