To the Editor.
—In their meta-analysis of RCTs, Midgley et al1 found a rather disappointing effect of dietary sodium restriction on blood pressure. Based on these findings, the authors question the wisdom of a sodium restriction in the general population and to a lesser extent in the hypertensive population. However, blood pressure is merely a surrogate endpoint that often, but not always, correlates with the real endpoints, ie, cardiovascular morbidity and mortality. Blood pressure also is an extremely variable measurement that is affected by myriad endogenous and exogenous pathophysiological factors throughout a 24-hour period. A parameter that more consistently reflects the average blood pressure load is LV wall thickness or LV mass. The LV mass has been shown to correlate better with 24-hour blood pressure measurements than with spot measurements and has been clearly identified as a surrogate endpoint for cardiovascular morbidity and mortality, which are far more meaningful than blood pressure
Messerli FH, Schmieder RE. Dietary Sodium and Blood Pressure. JAMA. 1996;276(18):1469. doi:10.1001/jama.1996.03540180025016