Ambulatory arterial stiffness index and 24-hour ambulatory pulse pressure as predictors of mortality in Ohasama, Japan.

Abstract

Ambulatory arterial stiffness index (AASI) and pulse pressure (PP) are indexes of arterial stiffness and can be computed from 24-hour blood pressure recordings. We investigated the prognostic value of AASI and PP in relation to fatal outcomes. In 1542 Ohasama residents (baseline age, 40 to 93 years; 63.4% women), we applied Cox regression to relate mortality to AASI and PP while adjusting for sex, age, BMI, 24-hour MAP, smoking and drinking habits, diabetes mellitus, and a history of cardiovascular disease. During 13.3 years (median), 126 cardiovascular and 63 stroke deaths occurred. The sex- and age-standardized incidence rates of cardiovascular and stroke mortality across quartiles were U-shaped for AASI and J-shaped for PP. Across quartiles, the multivariate-adjusted hazard ratios for cardiovascular and stroke death significantly deviated from those in the whole population in a U-shaped fashion for AASI, whereas for PP, none of the HRs departed from the overall risk. The hazard ratios for cardiovascular mortality across ascending AASI quartiles were 1.40 (P=0.04), 0.82 (P=0.25), 0.64 (P=0.01), and 1.35 (P=0.03). Additional adjustment of AASI for PP and sensitivity analyses by sex, excluding patients on antihypertensive treatment or with a history of cardiovascular disease, or censoring deaths occurring within 2 years of enrollment, produced confirmatory results. In a Japanese population, AASI predicted cardiovascular and stroke mortality over and beyond PP and other risk factors, whereas in adjusted analyses, PP did not carry any prognostic information.