Effectiveness of Cluster Level Behavioral Interventions to Reduce Salt Intake: A Systematic Review and Meta-analysis

BackgroundThe mean global salt intake is estimated at 10g/day much higher when compared to the WHO recommendation of less than 5g/day. Behavioral change interventions are most effective when applied at groups instead of individuals. The previous reviews on the topic did not compile evidence on cluster interventions. ObjectivesWe conducted a systematic review and meta-analysis to find out the effectiveness of cluster-level dietary interventions in reducing average daily salt intake and mean 24-hr urinary sodium excretion among general population. Search MethodsWe searched the following research databases using search terms relevant to this review - PubMed, EmBASE, Web of Science, Global Index Medicus, LILACS, Cochrane CENTRAL, TRoPHI databases, CTRI and WHO-ICTRP. Selection criteriaWe included published randomized controlled trials and quasi-experimental studies with interventions for population groups that reflect the resident communities. There were no restrictions for age or gender. We excluded the studies targeting patient groups with specific underlying health conditions. The primary outcomes were mean reduction in daily salt intake in g/day and the mean reduction in daily 24-hr Urine sodium output. Data collection and analysisTwo authors independently screened the titles, abstracts and full-text articles. Two review authors independently extracted data and assessed the risk of bias. We classified the complex interventions into six categories based on the principles of health promotion. The duration of follow-up (outcome assessment after the intervention) was classified as short ([&le;] 6 months), medium (6 to < 12 months) or long-term([&ge;] 12 months). Risk of bias was assessed using RoB2 tool for cluster RCTs and ROBINS-I tool for Non-randomized studies of intervention. We pooled effect size estimates from individual studies using generic inverse variance method using a random-effects model. Main resultsWe included 15 studies based on the selection criteria including 10 RCTs and 5 Non-randomised studies of Interventions (NRSI). Information and counselling measures, in the short-term, reduced the salt intake by 1.25g/day (95% CI: -1.9 to -0.6). At the medium-term, it was 0.47 g/day (95% CI: -0.81 to -0.14). On long term follow-up, it was 1.51g/day (95% CI: -2.62 to -0.4). Use of salt-monitoring tools reduced salt intake by 2.48 g/day (95% CI: -4.66 to -0.3). Environmental modification measures did not reduce salt intake significantly. DiscussionInformation and counselling interventions in conjunction with other measures effectively reduced the salt intake. When quantified, there was an average reduction up to 1.5g/day. Salt monitoring tools showed a greater effect in reducing dietary salt. A total of nine RCTs were assessed for risk of bias, of which five high-risk of bias. Among five Non-randomized studies of intervention, four of them showed serious risk of bias. An updated review in the future is likely to resolve these issues. Registration No.: PROSPERO (registration ID: CRD42020168783)