Results
REGRESSION, POSITIVE
We recruited 60 communities (10 in each province) into the study in October 2018. A total of 1576 participants from 788 families completed the baseline survey. The mean age was 55.8 (standard deviation 10.8) years, and 775 (49.2%) were male. During the trial, 157 (10%) participants were lost to follow-up as they moved to another county or were unable to attend follow-up assessments (Flowchart of participantsBaseline characteristics. Values are numbers (percentages) unless stated otherwiseSD=standard deviation.The establishment of a supportive environment intervention covered all the people living in the intervention communities. Data collected during the intervention showed that 953 posters were put up, and 10 510 leaflets and 5265 manuals were distributed to people living in the intervention communities. Short videos were played in the health service stations of 25 communities in five provinces (not in Qinghai). Loudspeaker broadcasts were played in 25 communities in five provinces (not in Sichuan). Six lectures and six salt intake monitoring activities were organised in all communities in the intervention group as planned. The number of people who took part in the lectures was 4975 (on average, 28 for each lecture in each community).The mean baseline urinary sodium excretion was 4418.7 (standard deviation 1973.7) mg per 24 hours in the control group and 4368.7 (1880.3) mg per 24 hours in the intervention group. During the 12 month trial, we observed decreases in sodium excretion in the two groups after adjustment for confounders. After adjustment, the mean difference between the intervention group and the control group was −336.8 (95% confidence interval −545.7 to −127.9) mg per 24 hours, which is equivalent to a 0.9 g per 24 hours decrease in salt intake (Results for 24 h urinary sodium excretion, potassium excretion, sodium-to-potassium ratio, and blood pressureCI=confidence interval; SD=standard deviation.Results were obtained from mixed linear model with random intercept of participants nested within family and random intercept of family nested within communities; all values for urinary outcomes were adjusted for age, sex, body mass index at baseline and follow-up, province, and education level. All values for blood pressure were further adjusted for outdoor temperature at baseline and follow-up, physical activity, and alcohol drinking status.Comparison of means within each group. Positive values indicate increase from baseline to 12 month follow-up; negative values indicate decrease from baseline to 12 month follow-up.Comparison between intervention group and control group in changes from baseline to 12 month follow-up. Positive values indicate that intervention group had greater increase or smaller decrease from baseline to 12 month follow-up compared with control group; negative values indicate that intervention group had greater decrease or smaller increase from baseline to 12 month follow-up compared with control group.Results for 24 hour urinary sodium excretion by subgroup (mg/24 h)CI=confidence interval; SD=standard deviation.Results were obtained from mixed linear model with random intercept of participants nested within family and random intercept of family nested within communities; all values for urinary outcomes were adjusted for age, sex, body mass index at baseline and follow-up, city, and education level.Comparison of means within each group. Positive values indicate increase from baseline to 12 month follow-up; negative values indicate decrease from baseline to 12 month follow-up.Comparison between intervention group and control group in changes from baseline to 12 month follow-up. Positive values indicate that intervention group had greater increase or smaller decrease from baseline to 12 month follow-up compared with control group; negative values indicate that intervention group had greater decrease or smaller increase from baseline to 12 month follow-up compared with control group.Age was defined as natural cubic spline with internal knots at 25th, 50th, and 75th centiles.
Results for knowledge, attitude, and behavioursCI=confidence interval; OR=odds ratio.Results were obtained from mixed effect logistic regression model with random intercept of participants nested within family and random intercept of family nested within communities; all values were adjusted for age, sex, body mass at baseline and follow-up, city, and education level.Questionnaires about using low sodium salt substitutes were filled out by people who had heard about low sodium salt substitutes.Supplementary tables E and F show the results of the sensitivity analyses. The mean effects on urinary sodium (−318.4 (−527.0 to −109.7) mg per 24 hours) and blood pressure (systolic −1.3 (−2.8 to 0.2) mm Hg; diastolic −0.7 (−1.7 to 0.2 ) mm Hg) were smaller if not adjusted for the confounders (supplementary table E). The mean effect was similar to the main results when possibly incomplete 24 hour urine collections were included (supplementary table F).