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Meta-Analysis
. 2020 Feb 17;10(2):e032941.
doi: 10.1136/bmjopen-2019-032941.

Effect of salt reduction interventions in lowering blood pressure in Chinese populations: a systematic review and meta-analysis of randomised controlled trials

Aoming Jin  1 , Wuxiang Xie  1 , Yangfeng Wu  2   3
Affiliations
Meta-Analysis

Effect of salt reduction interventions in lowering blood pressure in Chinese populations: a systematic review and meta-analysis of randomised controlled trials

Aoming Jin et al. BMJ Open. .

Abstract

Rationale and objective: Salt reduction remains a global challenge and different salt reduction strategies have been studied in China. This study is to systematically evaluate evidence from randomised controlled trials (RCT) in China and inform the effective salt reduction strategies.

Design: Systematic review and meta-analysis.

Data sources: MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Wanfang Data and the China National Knowledge Infrastructure databases through October 2019.

Eligibility criteria: RCTs conducted in China with at least 4 weeks' duration of study and blood pressure (BP) reported.

Data extraction and synthesis: Data were screened, extracted and appraised by two independent reviewers. The quality of study was assessed using a modified Cochrane Collaboration's risk of bias tool. The primary outcome was the difference in BP change from baseline to the end of study between interventions and control. The effects were pooled using a random effects model and associated factors were explored by a meta-regression.

Results: We identified 24 studies involving 10 448 participants, including 8 studies on health education (4583 participants), 2 studies on salt restriction diet (162 participants), 1 study on salt restriction spoon (50 participants) and 13 studies on salt substitute (5653 participants). Six studies on salt substitute and three studies on health education were identified with high quality. Pooled results from the six studies showed that salt substitutes significantly reduced systolic BP (-5.7 mm Hg; 95% CI -8.5 to -2.8) and diastolic BP (-2.0 mm Hg; 95% CI -3.5 to -0.4). The School-EduSalt study showed that the school-based health education significantly reduced systolic BP among parents (-2.3 mm Hg; 95% CI -4.5 to -0.04).

Conclusions: Among four salt reduction strategies studied in China with RCT design, only salt substitute was proved effective in lowering BP by the pooled effect from multiple studies with high quality. More well-designed studies are warranted for other strategies.

Keywords: hypertension; nutrition & dietetics; public health.

PubMed Disclaimer

Conflict of interest statement

Competing interests: YW has received a small research fund from Chongqing Jiankangyuan Health Technology to study the effect of a new salt substitute with very low sodium.

Figures

Figure 1
Figure 1
Flow diagram for study selection. RCT, randomised controlled trial.
Figure 2
Figure 2
Risk of bias summary by study and methodological domain. FM, family members of hypertensives; HD, haemodialysis; HE, health education; HT, hypertensives; ISH, isolated systolic hypertensives; NISH, not isolated systolic hypertensives; NT, normotensives; PD, peritoneal dialysis; SRD, salt restriction diet; SRS, salt restriction spoon; SS, salt substitute.
Figure 3
Figure 3
Forest plot of salt reduction interventions on effect in lowering systolic blood pressure among studies with high quality. ES, effect size.
Figure 4
Figure 4
Forest plot of salt reduction interventions on effect in lowering diastolic blood pressure among studies with high quality. ES, effect size.
See this image and copyright information in PMC

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