Arterial stiffness indices in healthy volunteers using non-invasive digital photoplethysmography

Background. Increased arterial stiffness is a marker of cardiovascular damage, even in the absence of clinically apparent disease. It is likely to become an important clinical tool in cardiovascular risk assessment. Aims and methods. We studied a group of healthy subjects and measured their arterial stiffness by digital photoplethysmography. We aimed to obtain a range of arterial stiffness values, and investigated the influence of age, gender, race, body mass index, fasting lipids and haemodynamic factors. Results. One hundred and fifty-two healthy subjects, aged between 18 and 67 years, on no medications and with no significant medical illnesses were recruited. The population was predominantly Caucasian (n=112). Two measures of arterial stiffness were obtained: stiffness index (SI), a measure of large arterial stiffness, and reflection index (RI), a measure of small to medium-sized arterial stiffness. SI and RI were significantly correlated with age, total cholesterol, low-density lipoprotein-cholesterol, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). Race was a significant independent predictor of SI. Conclusion. Digital photoplethysmography is a portable, operator-independent, reproducible and simple method of measuring arterial stiffness. Ranges of normality of arterial stiffness will depend on the individual's age, race, lipid levels, HR and blood pressure.