Abstract Body: Introduction The sodium sensitivity of blood pressure (SSBP) affects ~50% of hypertensive patients and increases hypertension risk. The SSBP is not routinely assessed and there is currently a lack of rapid and reliable clinical approaches to assess the SSBP. One recently proposed approach is the salt sensitivity index (SSI) which remains to be rigorously investigated as a tool to identify the SSBP.
Hypothesis The salt sensitivity index (SSI), derived from 24-hour ambulatory blood pressure (BP) data, can identify the SSBP via the classification of subjects at low, intermediate or high risk of the SSBP.
Methods Utilizing the Dietary Approaches to Stop Hypertension (DASH) – Sodium Trial control diet arm data for which validated ambulatory BP data was present during the high dietary salt intervention period (N=170, 54% Female, 46% Male) the SSI was calculated. Low SSI = dipping systolic BP (SBP) & HR<70 bpm, Intermediate SSI = non-dipping SBP and HR<70 bpm or dipping SBP & HR>70 bpm, High SSI = non-dipping SBP & HR>70 bpm. The predicted SSI risk was then correlated against the assessment of SSBP in the DASH-Sodium Trail cohort with SSBP defined as a >5mmHg increase in SBP between the low to high salt dietary intervention.
Results A High SSI Risk was identified in 61 subjects, Intermediate SSI Risk in 89 subjects, and a Low SSI Risk in 20 subjects. The accuracy of the SSI Risk (number true positives and negatives divided by total number of tested individuals) to predict the SSBP was 58% in the Low SSI Risk group i.e., 58% of Low SSI subjects were not salt sensitive. In the High SSI Risk group accuracy was 69%, i.e., 69% of high SSI risk subjects were salt sensitive. In the High SSI Risk group there was greater accuracy in the African American (AA) vs. non-AA group (73% vs. 63%, P<0.05) and higher accuracy in women vs. men (80% vs 56%, P<0.05)
Conclusion Our data, generated in the DASH-Sodium Trial control diet dataset, with the SSI calculated during the high salt intake intervention (which models a typical western dietary sodium intake), suggest that a High SSI risk has a high predictive accuracy for the SSBP that is comparable to the furosemide-based inpatient acute protocol. The SSI High risk category represents a potential approach for the assessment of the SSBP in the general population.