Abstract 55: Sodium Sensitivity, Sodium Resistance, and Incidence of Hypertension

Abstract

Background: Blood pressure responses to dietary sodium intake vary among individuals. However, it is unknown whether sodium sensitivity and sodium resistance predict incidence of hypertension. Methods: We conducted a feeding study, including a 7-day low-sodium diet (51.3 mmol/day) and a 7-day high-sodium diet (307.8 mmol/day), among 1,718 Chinese individuals with normal blood pressure in 2003-2005 and follow-up studies in 2008-2009 and 2011-2012. Three blood-pressure measurements and 24-hour urinary sodium excretion were obtained on each of 3 days during baseline, low- and high-sodium interventions, and follow-up visits. Latent class models were used to identify subgroups that share a similar underlying trajectory in blood-pressure responses to dietary sodium intake. Results: Three trajectories of systolic blood pressure responses to dietary sodium intake were identified (Figure). Mean (standard deviation) changes in systolic blood pressure were -13.7 (5.5), -4.9 (3.0), and 2.4 (3.0) mmHg during the low-sodium intervention, and 11.2 (5.3), 4.4 (4.1) and -0.2 (4.1) mmHg during the high-sodium intervention ( P< 0.001 for group differences) in high sodium-sensitive, moderate sodium-sensitive, and sodium-resistant groups, respectively. Compared to individuals with moderate sodium sensitivity, multiple-adjusted odds ratio (95% confidence intervals) for incident hypertension were 1.44 (1.03 to 1.99) for those with high sodium sensitivity and 1.42 (1.02 to 1.97) for those with sodium resistance ( P <0.001 for quadratic trend). Furthermore, a J-shaped association between systolic blood pressure responses to high sodium intake and incident hypertension was identified ( P <0.001). Similar results were observed for diastolic blood pressure. Conclusions: Individuals with either high sodium sensitivity or sodium resistance are at an increased risk for developing hypertension.