McLaren Lindsay, Sumar Nureen, Barberio Amanda M, Trieu Kathy, Lorenzetti Diane L, Tarasuk Valerie, Webster Jacqui, Campbell Norman Rc
Department of Community Health Sciences, Faculty of Medicine, University of Calgary, 3rd floor TRW, 3280 Hospital Dr. NW, Calgary, Alberta, Canada, T2N 4Z6.
Cochrane Database Syst Rev. 2016 Sep 16;9(9):CD010166. doi: 10.1002/14651858.CD010166.pub2.
Excess dietary sodium consumption is a risk factor for high blood pressure, stroke and cardiovascular disease. Currently, dietary sodium consumption in almost every country is too high. Excess sodium intake is associated with high blood pressure, which is common and costly and accounts for significant burden of disease. A large number of jurisdictions worldwide have implemented population-level dietary sodium reduction initiatives. No systematic review has examined the impact of these initiatives.
• To assess the impact of population-level interventions for dietary sodium reduction in government jurisdictions worldwide.• To assess the differential impact of those initiatives by social and economic indicators.
We searched the following electronic databases from their start date to 5 January 2015: the Cochrane Central Register of Controlled Trials (CENTRAL); Cochrane Public Health Group Specialised Register; MEDLINE; MEDLINE In Process & Other Non-Indexed Citations; EMBASE; Effective Public Health Practice Project Database; Web of Science; Trials Register of Promoting Health Interventions (TRoPHI) databases; and Latin American Caribbean Health Sciences Literature (LILACS). We also searched grey literature, other national sources and references of included studies.This review was conducted in parallel with a comprehensive review of national sodium reduction efforts under way worldwide (Trieu 2015), through which we gained additional information directly from country contacts.We imposed no restrictions on language or publication status.
We included population-level initiatives (i.e. interventions that target whole populations, in this case, government jurisdictions, worldwide) for dietary sodium reduction, with at least one pre-intervention data point and at least one post-intervention data point of comparable jurisdiction. We included populations of all ages and the following types of study designs: cluster-randomised, controlled pre-post, interrupted time series and uncontrolled pre-post. We contacted study authors at different points in the review to ask for missing information.
Two review authors extracted data, and two review authors assessed risk of bias for each included initiative.We analysed the impact of initiatives by using estimates of sodium consumption from dietary surveys or urine samples. All estimates were converted to a common metric: salt intake in grams per day. We analysed impact by computing the mean change in salt intake (grams per day) from pre-intervention to post-intervention.
We reviewed a total of 881 full-text documents. From these, we identified 15 national initiatives, including more than 260,000 people, that met the inclusion criteria. None of the initiatives were provided in lower-middle-income or low-income countries. All initiatives except one used an uncontrolled pre-post study design.Because of high levels of study heterogeneity (I > 90%), we focused on individual initiatives rather than on pooled results.Ten initiatives provided sufficient data for quantitative analysis of impact (64,798 participants). As required by the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) method, we graded the evidence as very low due to the risk of bias of the included studies, as well as variation in the direction and size of effect across the studies. Five of these showed mean decreases in average daily salt intake per person from pre-intervention to post-intervention, ranging from 1.15 grams/day less (Finland) to 0.35 grams/day less (Ireland). Two initiatives showed mean increase in salt intake from pre-intervention to post-intervention: Canada (1.66) and Switzerland (0.80 grams/day more per person. The remaining initiatives did not show a statistically significant mean change.Seven of the 10 initiatives were multi-component and incorporated intervention activities of a structural nature (e.g. food product reformulation, food procurement policy in specific settings). Of those seven initiatives, four showed a statistically significant mean decrease in salt intake from pre-intervention to post-intervention, ranging from Finland to Ireland (see above), and one showed a statistically significant mean increase in salt intake from pre-intervention to post-intervention (Switzerland; see above).Nine initiatives permitted quantitative analysis of differential impact by sex (men and women separately). For women, three initiatives (China, Finland, France) showed a statistically significant mean decrease, four (Austria, Netherlands, Switzerland, United Kingdom) showed no significant change and two (Canada, United States) showed a statistically significant mean increase in salt intake from pre-intervention to post-intervention. For men, five initiatives (Austria, China, Finland, France, United Kingdom) showed a statistically significant mean decrease, three (Netherlands, Switzerland, United States) showed no significant change and one (Canada) showed a statistically significant mean increase in salt intake from pre-intervention to post-intervention.Information was insufficient to indicate whether a differential change in mean salt intake occurred from pre-intervention to post-intervention by other axes of equity included in the PROGRESS framework (e.g. education, place of residence).We identified no adverse effects of these initiatives.The number of initiatives was insufficient to permit other subgroup analyses, including stratification by intervention type, economic status of country and duration (or start year) of the initiative.Many studies had methodological strengths, including large, nationally representative samples of the population and rigorous measurement of dietary sodium intake. However, all studies were scored as having high risk of bias, reflecting the observational nature of the research and the use of an uncontrolled study design. The quality of evidence for the main outcome was low. We could perform a sensitivity analysis only for impact.
AUTHORS' CONCLUSIONS: Population-level interventions in government jurisdictions for dietary sodium reduction have the potential to result in population-wide reductions in salt intake from pre-intervention to post-intervention, particularly if they are multi-component (more than one intervention activity) and incorporate intervention activities of a structural nature (e.g. food product reformulation), and particularly amongst men. Heterogeneity across studies was significant, reflecting different contexts (population and setting) and initiative characteristics. Implementation of future initiatives should embed more effective means of evaluation to help us better understand the variation in the effects.
过量摄入膳食钠是高血压、中风和心血管疾病的一个风险因素。目前，几乎每个国家的膳食钠摄入量都过高。过量的钠摄入与高血压相关，高血压很常见且成本高昂，造成了重大的疾病负担。全球许多司法管辖区都实施了针对全体人群的膳食钠减少倡议。尚无系统评价对这些倡议的影响进行过考察。
•评估全球政府司法管辖区针对全体人群的膳食钠减少干预措施的影响。•评估这些倡议根据社会和经济指标产生的差异影响。
我们检索了以下电子数据库，检索时间从其建库起始日期至2015年1月5日：Cochrane对照试验中心注册库（CENTRAL）；Cochrane公共卫生小组专业注册库；MEDLINE；MEDLINE在研及其他未索引引文；EMBASE；有效公共卫生实践项目数据库；科学引文索引；促进健康干预试验注册库（TRoPHI）数据库；以及拉丁美洲和加勒比健康科学文献数据库（LILACS）。我们还检索了灰色文献、其他国家来源以及纳入研究的参考文献。本评价与一项正在进行的对全球各国钠减少努力的全面评价（Trieu 2015）并行开展，通过该评价我们直接从国家联系人处获得了更多信息。我们未对语言或出版状态加以限制。
我们纳入了针对全体人群的膳食钠减少倡议（即针对全球范围内的全体人群，在本案例中为政府司法管辖区），且具有至少一个干预前数据点以及至少一个可比司法管辖区的干预后数据点。我们纳入了所有年龄段的人群以及以下几种研究设计类型：整群随机、对照前后、中断时间序列和非对照前后。在评价过程中的不同阶段，我们与研究作者联系以索要缺失的信息。
两名评价作者提取数据，两名评价作者评估每个纳入倡议的偏倚风险。我们通过使用膳食调查或尿液样本中钠摄入量的估计值来分析倡议的影响。所有估计值均转换为一个通用指标：每日盐摄入量（克）。我们通过计算从干预前到干预后盐摄入量（克/天）的平均变化来分析影响。
我们共检索了881篇全文文献。从中，我们确定了15项国家倡议，涉及超过260,000人，符合纳入标准。没有一项倡议来自中低收入或低收入国家。除一项倡议外，所有倡议均采用非对照前后研究设计。由于研究异质性水平较高（I²>90%），我们关注的是单个倡议而非汇总结果。10项倡议提供了足够的数据用于影响的定量分析（64,798名参与者）。根据推荐分级、评估、制定与评价（GRADE）方法的要求，由于纳入研究存在偏倚风险，以及各研究间效应方向和大小的差异，我们将证据质量评为极低。其中5项倡议显示从干预前到干预后人均每日盐摄入量平均下降，范围从减少1.15克/天（芬兰）到减少0.35克/天（爱尔兰）。两项倡议显示从干预前到干预后盐摄入量平均增加：加拿大（增加1.66克/天）和瑞士（每人每天增加0.80克）。其余倡议未显示出具有统计学意义的平均变化。10项倡议中有7项是多组分的，并纳入了结构性干预活动（如食品配方改革、特定环境下的食品采购政策）。在这7项倡议中，4项显示从干预前到干预后盐摄入量有统计学意义的平均下降，范围从芬兰到爱尔兰（见上文），1项显示从干预前到干预后盐摄入量有统计学意义的平均增加（瑞士；见上文）。9项倡议允许按性别（分别为男性和女性）对差异影响进行定量分析。对于女性，3项倡议（中国、芬兰、法国）显示有统计学意义的平均下降，4项（奥地利,荷兰,瑞士,英国）无显著变化，2项（加拿大,美国）显示从干预前到干预后盐摄入量有统计学意义的平均增加。对于男性，5项倡议（奥地利、中国、芬兰、法国、英国）显示有统计学意义的平均下降，3项（荷兰、瑞士、美国）无显著变化，1项（加拿大）显示从干预前到干预后盐摄入量有统计学意义的平均增加。信息不足，无法表明在PROGRESS框架所包含的其他公平性维度（如教育、居住地点）上，从干预前到干预后平均盐摄入量是否发生了差异变化。我们未发现这些倡议有任何不良影响。倡议数量不足以进行其他亚组分析，包括按干预类型、国家经济状况和倡议持续时间（或起始年份）分层。许多研究具有方法学优势，包括大规模、具有全国代表性的人群样本以及对膳食钠摄入量的严格测量。然而，所有研究的偏倚风险评分均为高，这反映了研究的观察性本质以及使用非对照研究设计。主要结局的证据质量较低。我们仅能对影响进行敏感性分析。
政府司法管辖区针对全体人群的膳食钠减少干预措施有可能使人群从干预前到干预后盐摄入量出现总体下降，特别是如果这些措施是多组分的（不止一项干预活动）且纳入了结构性干预活动（如食品配方改革），尤其是在男性中。研究间的异质性显著，反映了不同的背景（人群和环境）以及倡议特征。未来倡议的实施应采用更有效的评估方法，以帮助我们更好地理解效果的差异。
