Validation of the Detection of The Salt Sensitivity of Blood Pressure from 24-hour Ambulatory Blood Pressure Monitoring Data

The salt sensitivity of blood pressure (SSBP) is rarely assessed and represents a critical barrier in precision hypertension treatment. The current approaches to assess salt sensitivity are labor and resource intensive limiting their clinical implementation. The salt sensitivity index (SSI), derived from 24-hour ambulatory blood pressure monitoring (ABPM) data, has been proposed as a clinical diagnostic approach to classify individuals at low-, intermediate-, or high-risk for the SSBP. This study utilized the Dietary Approaches to Stop Hypertension (DASH)-Sodium Trial control diet arm dataset (N=170), in which the SSBP was assessed by the gold standard dietary approach, to address the hypothesis that identification of a high-risk SSI can predict the individual SSBP. In the high-risk SSI category 72% of DASH-Sodium Trial participants exhibited a salt-sensitive phenotype. For all participants with a high-risk SSI (male and female and normotensive and hypertensive) sensitivity (ability to correctly identify individuals with the SSBP) was 85%, specificity (ability to correctly identify individuals without the SSBP) was 41%, positive predictive value (probability that a person who tests positive has the SSBP) was 72%, negative predictive value was 60% (probability that a person who tests negative does not have the SSBP) and accuracy was 69%. For hypertensive participants only with a high-risk SSI (males and females), sensitivity was 86%, specificity was 44%, the positive predictive value increased to 83%, the negative predictive value was 50% and accuracy increased to 76%. This study validates the identification of a high-risk SSI, based on 24-hour ABPM, as a generalizable implementable approach for the clinical diagnosis of the SSBP, with a potential greater clinical diagnostic value in hypertensive versus normotensive individuals.