Benefit assessment of salt reduction in patients with hypertension: systematic overview

Abstract

We assessed the benefits and harm of reduced salt intake in patients with essential hypertension focusing on patient-relevant outcomes and blood pressure. A systematic search of five electronic databases was performed to identify high-quality secondary literature based on randomized controlled trials (RCTs). An update primary literature search (RCTs) was performed for the time period up to 2010 that was not covered by secondary literature. Major outcomes were death, cardiovascular morbidity/mortality, hospital stays, terminal renal failure, quality of life, and adverse events. Change in blood pressure was defined as surrogate parameter. Four different systematic reviews and two RCTs met the inclusion criteria. Only one review reported limited data on patient-relevant outcomes. Over an intervention period of up to 12 months, mean SBP was reduced by 3.6-8.0 mmHg in all reviews. For the same intervention period, a statistically significant advantage with regard to mean DBP reduction ranging from 1.9 to 2.8 mmHg was found in three reviews. The fourth publication reported a nonsignificant reduction (DBP reduction of 4.7 mmHg). None of the RCTs identified in the primary literature search update reported data on patient-relevant outcomes. However, both RCTs found blood pressure improvements with salt reduction. A benefit from a salt-reduced diet in patients with high blood pressure is not proven with regard to patient-relevant outcomes based on systematic reviews and RCTs published up to 2010. The results indicate a blood pressure-lowering effect through reduced salt intake in hypertensive patients.