Prediction of stroke using an algorithm to estimate arterial stiffness.

Background: Arterial stiffness is important because it is associated with adverse cardiovascular events including stroke. Methods that are based on pulse wave velocity have significant limitations in estimating arterial stiffness. The purpose of this paper is to present a novel easy to apply non-invasive method to estimate arterial stiffness that is based on pulse pressure.

Methods: Two indices to estimate arterial stiffness, (1) arterial stiffness 1 (AS1) and (2) arterial stiffness 2 (AS2) were developed and applied in two National Institutes of Health funded clinical trials, the Systolic Hypertension in the Elderly Program and the Systolic Blood Pressure Intervention Trial. These indices were developed by fitting individual survival models for selected predictor variables to the response, i.e. time to stroke, by selecting the coefficients that were statistically significant at the 0.05 level after adjusting the variable weights. The indices were derived as the weighted linear combination of the coefficients.

Results: AS1 and AS2 performed well in two goodness of fit criteria i.e. overall model p-value and concordance correlation. Comparison of Cox models using indices AS1 and AS2 and chronological age indicated that AS1 and AS2 independently predicted the occurrence of stroke at five years better than chronological age. Nearly identical effects were observed when the analyses were limited to Black participants in SPRINT with a concordance correlation of 0.80 and log rank test p-value of 0.007.

Conclusion: These indices that are derived from pulse pressure predict the occurrence of stroke better than either pulse pressure or chronological age alone and may be used in designing new randomized clinical trials, and possibly incorporated in hypertension and stroke guidelines.