An Appraisal of Methods Recently Recommended for Testing Salt Sensitivity of Blood Pressure

A ccording to a recent Scientific Statement of the American Heart Association (AHA), salt sensitivity of blood pressure (BP) is a trait in which BP “changes parallel to changes in salt intake.” It is said that salt sensitivity is “a risk factor for cardiovascular mortality and morbidity, independent of and as powerful as BP.” Although the criteria for identifying salt sensitivity are not standardized, it has been estimated that 30% to 50% of hypertensive humans are salt sensitive and 25% of normotensive humans are salt sensitive. According to the AHA Scientific Statement, salt sensitivity of BP has become “an issue of clinical importance because the phenotype carries prognostic implications potentially as strong as those of traditional cardiovascular risk factors.” Various methods of testing for salt sensitivity have been applied in research settings; however, tests for salt sensitivity that are useful in routine clinical practice have yet to be identified. Advances in understanding of the mechanisms and clinical significance of salt sensitivity have long been hampered by the lack of standardization in the methods used for assessing salt sensitivity. In this analysis, we discuss the main research methods of testing for salt sensitivity and present current views on how best to assess this complex phenotype, including many views that were not addressed by the recent AHA Scientific Statement. To broaden the scientific consideration, we also present alternative perspectives on the contention that salt sensitivity is a risk factor for cardiovascular mortality “independent of and as powerful as BP.”