The Effects of a Community-Based Sodium Reduction Program in Rural China – A Cluster-Randomized Trial

Background
Average sodium intake and stroke mortality in northern China are both among the highest in the world. An effective, low-cost strategy to reduce sodium intake in this population is urgently needed.
Objective
We sought to determine the effects of a community-based sodium reduction program on salt consumption in rural northern China.
Design
This study was a cluster-randomized trial done over 18 months in 120 townships (one village from each township) from five provinces. Sixty control villages were compared to 60 intervention villages that were given access to a reduced-sodium, added-potassium salt substitute in conjunction with a community-based health education program focusing on sodium reduction. The primary outcome was the difference in 24-hour urinary sodium excretion between randomized groups.
Results
Among 1,903 people with valid 24-hour urine collections, mean urinary sodium excretion in intervention compared with control villages was reduced by 5.5% (-14mmol/day, 95% confidence interval -26 to -1; p = 0.03), potassium excretion was increased by 16% (+7mmol/day, +4 to +10; p<0.001), and sodium to potassium ratio declined by 15% (-0.9, -1.2 to -0.5; p<0.001). Mean blood pressure differences were -1.1 mm Hg systolic (-3.3 to +1.1; p = 0.33) and -0.7 mm Hg diastolic (-2.2 to +0.8, p = 0.35) and the difference in the proportion with hypertension was -1.3% (-5.1 to 2.5, p = 0.56).
Conclusion
There were clear differences in population sodium and potassium intake between villages that were most likely a consequence of increased use of salt substitute. The absence of effects on blood pressure reflects the moderate changes in sodium and potassium intake achieved.
Trial Registration
Clinicaltrials.gov identifier: NCT01259700.

背景：中国北方地区居民的人均钠摄入量与脑卒中死亡率均位列全球高位，该人群亟需一种高效、低成本的减钠干预策略。
研究目的：本研究旨在评估以社区为基础的减钠干预项目对中国北方农村地区居民食盐摄入量的影响。
研究设计：本研究为整群随机对照试验（cluster-randomized trial），于中国北方五省的120个乡镇（每个乡镇选取1个行政村）开展，研究周期为18个月。研究将60个对照村与60个干预村进行对比：干预村可获得低钠高钾盐替代盐（reduced-sodium, added-potassium salt substitute），并配套实施以减钠为核心的社区健康教育项目。本研究的主要结局指标为随机分组两组间24小时尿钠排泄量的差值。
研究结果：在完成有效24小时尿液样本采集的1903名研究对象中，干预村居民的平均尿钠排泄量较对照村降低5.5%（日均减少14mmol，95%置信区间：-26至-1；P=0.03）；尿钾排泄量升高16%（日均增加7mmol，95%置信区间：+4至+10；P<0.001）；钠钾比降低15%（差值为-0.9，95%置信区间：-1.2至-0.5；P<0.001）。收缩压平均差值为-1.1mmHg（95%置信区间：-3.3至+1.1；P=0.33），舒张压平均差值为-0.7mmHg（95%置信区间：-2.2至+0.8；P=0.35）；高血压患病率的组间差值为-1.3%（95%置信区间：-5.1至2.5；P=0.56）。
研究结论：干预村与对照村居民的钠、钾摄入水平存在显著差异，这极有可能源于居民对低钠高钾盐替代盐使用量的增加。本研究未观察到干预对血压的显著影响，这或与本次研究中钠、钾摄入的变化幅度相对温和有关。
试验注册：ClinicalTrials.gov注册号：NCT01259700。