Arch Hellen Med, 31(6), November-December 2014, 725-734
Prediction of all-cause mortality in the elderly using a novel method
T.G. Papaioannou,1,2 A.D. Protogerou,2 N. Stergiopοulos,3 O. Vardoulis,3 M. Safar,4 J. Blacher,4 C. Stefanadis1
OBJECTIVE Ageing of the population is increasing and the current predictive models of mortality in the elderly are not accurate. New biomarkers that predict cardiovascular (CV) risk and mortality in the elderly are demanding. Aortic stiffness, assessed by carotid-to-femoral pulse wave velocity (PWV), often fails to predict CV risk and mortality in the elderly, although its predictive value has been well established in other populations. Total arterial compliance (CT) is the most relevant arterial property regarding CV function, in comparison to local or regional arterial stiffness and it may thus be superior to PWV for the prediction of CV risk and mortality. Current methods for CT estimation are either complex to use or inaccurate. A new method for CT estimation, based on PWV, was recently proposed and validated in silico, demonstrating a high degree of accuracy, but it has not yet been applied in vivo. This study aimed to investigate the ability of CT to predict all-cause mortality in the elderly.
METHOD PWV was estimated in 279 elderly subjects (85.5±7.0 years) who were followed up for a mean period of 12.8±6.3 months. CT was estimated by the formula CT=kxPWV-2. The coefficient k is body-size dependent as previously demonstrated in silico using a validated mathematical arterial model; here k was adjusted for body mass index (BMI).
RESULTS Survivors (n=185) and nonsurvivors (n=94) had similar PWV (14.2±3.6 vs 14.9±3.8 m/sec, respectively; p=0.139). In contrast, non-survivors had significantly lower CT than survivors (0.198±0.128 vs 0.221±0.1 mL/mmHg; p=0.018). CT was a significant predictor of mortality (p=0.022, odds ratio=0.326), while PWV was not (p=0.202), even after adjustment for gender, mean blood pressure and heart rate. Age was an independent determinant of CT (p=0.016), but not of PWV.
CONCLUSIONS CT, estimated by a novel method, can predict all-cause mortality in the elderly. CT may be a more sensitive arterial biomarker than PWV for CV risk assessment, especially in the elderly.
Key words: Ageing, Aortic elasticity, Arterial stiffness, Elderly, Mortality, Pulse wave velocity.