Effectiveness of self-monitoring devices measuring the urinary sodium-to-potassium ratio, urinary salt (sodium) excretion, or salt concentration in foods for blood pressure management: a systematic review and meta-analysis.

Self-monitoring devices that measure the urinary sodium-to-potassium (Na/K) ratio, urinary salt or sodium excretion, or salt concentration in foods have emerged as tools that can guide dietary adjustments for blood pressure (BP) control. This systematic review and meta-analysis investigated whether these self-monitoring devices can help to control BP in adults. The PubMed, Cochrane Library, and Ichushi-Web databases were searched to identify randomized controlled trials that compared the effect of these devices (with or without additional dietary education) plus usual care on BP with that of usual care alone. The pooled effect of weighted mean difference between the intervention and control groups at the end of follow-up was estimated by random-effects meta-analysis. The primary outcome was the change in BP. Secondary outcomes included changes in the urinary Na/K ratio, and sodium and potassium excretions. Of 1525 studies screened, eight (with 1442 participants) were eligible for inclusion. Meta-analysis showed greater reductions in systolic BP by 2.45 (95% confidence interval, 0.04, 4.86) mmHg and diastolic BP by 1.38 (-0.15, 2.90) mmHg in the intervention vs. control groups. However, heterogeneity was high (I² = 69.4% for systolic BP and 65.1% for diastolic BP). The BP-lowering effect was not statistically different across different follow-up durations (4 weeks or 2-6 months) and intervention approaches (self-monitoring alone or combined with dietary education) (all p values for heterogeneity >0.1). Reductions in the urinary Na/K ratio and sodium excretion were greater in the intervention group. Self-monitoring devices may assist with BP reduction by promoting decreased sodium intake and increased potassium intake.