Measurement of Stiffness Index by Digital Volume Pulse Analysis Technique: Clinical Utility in Cardiovascular Disease Risk Stratification

BACKGROUND: Indices of arterial stiffness are accepted as independent markers of cardiovascular disease (CVD), having both positive prognostic and diagnostic implications. The utility of stiffness index (SI) derived from digital volume pulse (DVP) analysis in CVD risk screening is not established. METHODS: Using a representative sample of individuals from local communities (West Midlands, UK), we determined the performance of SI in the discrimination of increasing CVD risk. Arterial stiffness was measured by DVP photoplethysmography (PCA 2; Micro Medical) using a direct, standardized approach. CVD risk assessment was performed in accordance with the Joint British Society guidelines (JBS2). RESULTS: Of our cohort of 247 individuals (51% male; mean age 55.2 (s.d. 10.3) years), 187 were apparently healthy and 60 had established CVD risk factors (diabetes mellitus: 33%, hypertension: 77.8%, hypercholesteremia: 61%). On univariate analysis, SI was strongly associated with CVD risk (the European Society of Cardiology (ESC) based HeartScore) (Pearson correlation coefficient (R): 0.56, P < or = 0.001) and increased in an ordinal fashion from "low risk" to "medium risk" to "high risk" to "very high risk" (pseudo R2 = 0.30; P < 0.001). In receiver operator characteristic curve analysis, SI was the best discriminator between low to medium risk and high-risk categories (area under curve (AUC): 0.76 (95% CI 0.64-0.88), P < 0.001) when compared to total cholesterol, plasma glucose, systolic blood pressure, and waist-to-hip ratio and had the utility to discriminate the individuals with known CVD risk factors such as diabetes and hypertension. CONCLUSION: Noninvasive measurements of arterial stiffness may aid the optimal stratification of CVD risk in an apparently healthy population.