Impact of age on the independent association of adiposity with pulse-wave velocity in a population sample of African ancestry

BACKGROUND We aimed to clarify whether age influences the independent relationship between adiposity and pulse-wave velocity (PWV). METHODS We explored the effect of age on the independent relationships between indexes of central adiposity (waist circumference (WC) and waist-to-hip ratio (WHR)) and carotid-femoral PWV, central augmentation index (Al-c), or pressure wave amplification assessed from applanation tonometry measurements obtained at the radial, carotid, and femoral arteries in 508 randomly selected subjects > 16 years of age in a population sample of African ancestry with a high prevalence of excess adiposity (similar to 63% overweight or obese). RESULTS In women a strong interaction between age and either WC or WHR was associated with logPWV independent of confounders and the individual terms(r=0.68,P < 0.0001). This translated into a markedly greater increase in logPWV with increases in either WC or WHR in women older than the median age as compared to women younger (slopes of WC-IogPWV relationships = 0.0031 +/- 0.0009 vs. -0.0007 +/- 0.0007, P < 0.002). In women older than the median age for the group, a one s.d. increase in WC (112.8 cm) translated into a 0.70 m/s increase in PWV as compared to a 0.14 m/s decrease in PWV for each one s.d. increase in WC (13.0 cm) in women younger than the median age (P < 0.001). No index of adiposity was independently associated with the log of Al-c or aortic-brachial wave amplification. CONCLUSION In women of African ancestry, a greater independent effect of adiposity on PWV is noted in older as compared to younger women.