Derivation and validation of diagnostic thresholds for central blood pressure measurements based on long-term cardiovascular risks.

OBJECTIVES: This study sought to derive and validate outcome-driven thresholds of central blood pressure (CBP) for diagnosing hypertension.
BACKGROUND: Current guidelines for managing patients with hypertension mainly rely on blood pressure (BP) measured at brachial arteries (cuff BP). However, BP measured at the central aorta (central BP [CBP]) may be a better prognostic factor for predicting future cardiovascular events than cuff BP.
METHODS: In a derivation cohort (1,272 individuals and a median follow-up of 15 years), we determined diagnostic thresholds for CBP by using current guideline-endorsed cutoffs for cuff BP with a bootstrapping (resampling by drawing randomly with replacement) and an approximation method. To evaluate the discriminatory power in predicting cardiovascular outcomes, the derived thresholds were tested in a validation cohort (2,501 individuals with median follow-up of 10 years).
RESULTS: The 2 analyses yielded similar diagnostic thresholds for CBP. After rounding, systolic/diastolic threshold was 110/80 mm Hg for optimal BP and 130/90 mm Hg for hypertension. Compared with optimal BP, the risk of cardiovascular mortality increased significantly in subjects with hypertension (hazard ratio: 3.08, 95% confidence interval: 1.05 to 9.05). Of the multivariate Cox proportional hazards model, incorporation of a dichotomous variable by defining hypertension as CBP ≥ 130/90 mm Hg was associated with the largest contribution to the predictive power.
CONCLUSIONS: CBP of 130/90 mm Hg was determined to be the cutoff limit for normality and was characterized by a greater discriminatory power for long-term events in our validation cohort. This report represents an important step toward the application of the CBP concept in clinical practice.