Salt sensitivity, pulse pressure, and death in normal and hypertensive humans

Although factors such as age, blood pressure, and its responsiveness to cha nges in sodium balance and extracellular fluid volume status (salt sensitiv ity) are associated with an increased risk of end-organ disease and cardiov ascular events in hypertensive subjects, no such relationship with mortalit y has been demonstrated for salt sensitivity in normotensive subjects. We c onducted long-term follow-up of 430 normal and 278 hypertensive subjects in whom assessment of salt sensitivity of blood pressure was performed as lon g as 27 years ago. We ascertained the status of 596 subjects (85% of the to tal population), 123 (21%) of whom had died. The following initial measurem ents were significantly (P<0.002) associated with subjects who had died com pared with subjects known to be alive: age at study, pulse pressure, systol ic, diastolic, and mean arterial pressures, hypertension, salt sensitivity, baseline renin levels, and body mass index (but not body weight). A stepwi se logistic regression found the following independent predictors of death (odds ratio, 95% CI): age at initial study (1.08, 1.06 to 1.10), baseline b lood pressure (1.03, 1.01 to 1.04), sodium sensitivity (1.73, 1.02 to 2.94) , and male gender (1.91, 1.15 to 3.17). When survival curves were examined, normotensive salt-sensitive subjects aged >25 years when initially studied were found to have a cumulative mortality similar to that of hypertensive subjects, whereas salt-resistant normotensive subjects had increased surviv al (P<0.001). These observations provide unique evidence of a relationship between salt sensitivity and mortality that is independent of elevated bloo d pressure.