A diagnostic prediction model for hypertension in Han and Yugur population from the China National Health Survey (CNHS).

BACKGROUND: The prevalence of hypertension is high among Chinese adults, thus, identifying non-hypertensive individuals at high risk for intervention will help to improve the efficiency of primary prevention strategies. METHODS: The cross-sectional data on 9699 participants aged 20 to 80 years were collected from the China National Health Survey in Gansu and Hebei provinces in 2016 to 2017, and they were nonrandomly split into the training set and validation set based on location. Multivariable logistic regression analysis was performed to develop the diagnostic prediction model, which was presented as a nomogram and a website with risk classification. Predictive performances of the model were evaluated using discrimination and calibration, and were further compared with a previously published model. Decision curve analysis was used to calculate the standardized net benefit for assessing the clinical usefulness of the model. RESULTS: The Lasso regression analysis identified the significant predictors of hypertension in the training set, and a diagnostic model was developed using logistic regression. A nomogram with risk classification was constructed to visualize the model, and a website ( https://chris-yu.shinyapps.io/hypertension_risk_prediction/ ) was developed to calculate the exact probabilities of hypertension. The model showed good discrimination and calibration, with the C-index of 0.789 (95% confidence interval [CI]: 0.768, 0.810) through internal validation and 0.829 (95% CI: 0.816, 0.842) through external validation. Decision curve analysis demonstrated that the model was clinically useful. The model had a higher area under receiver operating characteristic curves in training and validation sets compared with a previously published diagnostic model based on Northern China population. CONCLUSION: This study developed and validated a diagnostic model for hypertension prediction in Gansu Province. A nomogram and a website were developed to make the model conveniently used to facilitate the individualized prediction of hypertension in the general population of Han and Yugur.

Cost-Effectiveness of a Household Salt Substitution Intervention: Findings From 20 995 Participants of the Salt Substitute and Stroke Study.

BACKGROUND: SSaSS (Salt Substitute and Stroke Study), a 5-year cluster randomized controlled trial, demonstrated that replacing regular salt with a reduced-sodium, added-potassium salt substitute reduced the risks of stroke, major adverse cardiovascular events, and premature death among individuals with previous stroke or uncontrolled high blood pressure living in rural China. This study assessed the cost-effectiveness profile of the intervention. METHODS: A within-trial economic evaluation of SSaSS was conducted from the perspective of the health care system and consumers. The primary health outcome assessed was stroke. We also quantified the effect on quality-adjusted life-years (QALYs). Health care costs were identified from participant health insurance records and the literature. All costs (in Chinese yuan [¥]) and QALYs were discounted at 5% per annum. Incremental costs, stroke events averted, and QALYs gained were estimated using bivariate multilevel models. RESULTS: Mean follow-up of the 20 995 participants was 4.7 years. Over this period, replacing regular salt with salt substitute reduced the risk of stroke by 14% (rate ratio, 0.86 [95% CI, 0.77-0.96]; P=0.006), and the salt substitute group had on average 0.054 more QALYs per person. The average costs (¥1538 for the intervention group and ¥1649 for the control group) were lower in the salt substitute group (¥110 less). The intervention was dominant (better outcomes at lower cost) for prevention of stroke as well as for QALYs gained. Sensitivity analyses showed that these conclusions were robust, except when the price of salt substitute was increased to the median and highest market prices identified in China. The salt substitute intervention had a 95.0% probability of being cost-saving and a >99.9% probability of being cost-effective. CONCLUSIONS: Replacing regular salt with salt substitute was a cost-saving intervention for the prevention of stroke and improvement of quality of life among SSaSS participants.

Long-term exposure to ambient nitrogen dioxide and ozone modifies systematic low-grade inflammation: The CHCN-BTH study.

The potential effect of long-term exposure to ambient air pollutants on low-grade systematic inflammation has seldom been evaluated taking indoor air pollution and self-protection behaviors on smog days into account. A total of 24,346 participants at baseline were included to conduct a cross-sectional study. The annual (2016) average pollutant concentrations were assessed by air monitoring stations for PM2.5, PM10, SO2, NO2, O3 and CO. Associations between annual ambient air pollution and low-grade systematic inflammation (hsCRP>3 mg/L) were estimated by generalized linear mixed models. Stratification analysis was also performed based on demographic characteristics, health-related behaviors and disease status. Annual ambient NO2 and O3 were all associated with low-grade systematic inflammation in single-pollutant models after adjusting for age, sex, blood lipids, blood pressure, lifestyle risk factors, cooking fuel, heating fuel and habits during smog days (NO2 per 10 µg/m3: OR = 1.057, P = 0.018; O3 per 10 µg/m3: OR = 0.953, P = 0.012). The 2-year and 3-year ozone concentrations were consistently associated with lower systematic inflammation (2-year O3 per 10 µg/m3: OR = 0.959, P = 0.004; 3-year O3 per 10 µg/m3: OR = 0.961, P = 0.014). In two-pollutant models, the estimated effects of annual NO2 and O3 on low-grade systematic inflammation remained stable. The effect size of annual pollutants on inflammation increased in participants without air-purifier usage (NO2 per 10 µg/m3: OR = 1.079, P = 0.009; O3 per 10 µg/m3: OR = 0.925, P = 0.001), while the association was null in the air-purifier usage group. Thus, long-term exposure to ambient NO2 and O3 was associated with low-grade systemic inflammation, and the results were generally stable after sensitivity analysis. The usage of air purifiers on smog days can modify the association between gaseous pollutants and systematic inflammation.

Factors Associated With the Use of a Salt Substitute in Rural China.

Importance: Lowering sodium intake reduces blood pressure and may reduce the risk of cardiovascular diseases. The use of reduced-sodium salt (a salt substitute) may achieve sodium reduction, but its effectiveness may be associated with the context of its use. Objective: To identify factors associated with the use of salt substitutes in rural populations in China within the Salt Substitute and Stroke Study, a large-scale cluster randomized trial. Design, Setting, and Participants: This sequential mixed-methods qualitative evaluation, conducted from July 2 to August 28, 2018, in rural communities across 3 provinces in China, included a quantitative survey, collection of 24-hour urine samples, and face-to-face interviews. A random subsample of trial participants, selected from the 3 provinces, completed the quantitative survey (n = 1170) and provided urine samples (n = 1025). Interview respondents were purposively selected from the intervention group based on their different ranges of urinary sodium excretion levels. Statistical analysis was performed from September 18, 2018, to February 22, 2019. Exposures: The intervention group of the Salt Substitute and Stroke Study was provided with the free salt substitute while the control group continued to use regular salt. Main Outcomes and Measures: Knowledge, attitudes, and behaviors regarding the use of the salt substitute were measured using quantitative surveys, and urinary sodium levels were measured using 24-hour urine samples. Contextual factors were explored through semistructured interviews and integrated findings from surveys and interviews. Results: A total of 1170 individuals participated in the quantitative survey. Among the 1025 participants with successful urine samples, the mean (SD) age was 67.4 (7.5) years, and 502 (49.0%) were female. The estimated salt intake of participants who believed that high salt intake was good for health was higher; however, it was not significantly different (0.84 g/d [95% CI, -0.04 to 1.72 g/d]) from those who believed that high salt intake was bad for health. Thirty individuals participated in the qualitative interviews (18 women [60.0%]; mean [SD] age, 70.3 [6.0] years). Quantitative and qualitative data indicated high acceptability of and adherence to the salt substitute. Contextual factors negatively associated with the use of the salt substitute included a lack of knowledge about the benefits associated with salt reduction and consumption of high-sodium pickled foods. In addition, reduced antihypertensive medication was reported by a few participants using the salt substitute. Conclusions and Relevance: This study suggests that lack of comprehensive understanding of sodium reduction and salt substitutes and habitual consumption of high-sodium foods (such as pickled foods) were the main barriers to the use of salt substitutes to reduce sodium intake. These factors should be considered in future population-based, sodium-reduction interventions.

Effect of Salt Substitution on Cardiovascular Events and Death.

BACKGROUND: Salt substitutes with reduced sodium levels and increased potassium levels have been shown to lower blood pressure, but their effects on cardiovascular and safety outcomes are uncertain. METHODS: We conducted an open-label, cluster-randomized trial involving persons from 600 villages in rural China. The participants had a history of stroke or were 60 years of age or older and had high blood pressure. The villages were randomly assigned in a 1:1 ratio to the intervention group, in which the participants used a salt substitute (75% sodium chloride and 25% potassium chloride by mass), or to the control group, in which the participants continued to use regular salt (100% sodium chloride). The primary outcome was stroke, the secondary outcomes were major adverse cardiovascular events and death from any cause, and the safety outcome was clinical hyperkalemia. RESULTS: A total of 20,995 persons were enrolled in the trial. The mean age of the participants was 65.4 years, and 49.5% were female, 72.6% had a history of stroke, and 88.4% a history of hypertension. The mean duration of follow-up was 4.74 years. The rate of stroke was lower with the salt substitute than with regular salt (29.14 events vs. 33.65 events per 1000 person-years; rate ratio, 0.86; 95% confidence interval [CI], 0.77 to 0.96; P = 0.006), as were the rates of major cardiovascular events (49.09 events vs. 56.29 events per 1000 person-years; rate ratio, 0.87; 95% CI, 0.80 to 0.94; P<0.001) and death (39.28 events vs. 44.61 events per 1000 person-years; rate ratio, 0.88; 95% CI, 0.82 to 0.95; P<0.001). The rate of serious adverse events attributed to hyperkalemia was not significantly higher with the salt substitute than with regular salt (3.35 events vs. 3.30 events per 1000 person-years; rate ratio, 1.04; 95% CI, 0.80 to 1.37; P = 0.76). CONCLUSIONS: Among persons who had a history of stroke or were 60 years of age or older and had high blood pressure, the rates of stroke, major cardiovascular events, and death from any cause were lower with the salt substitute than with regular salt. (Funded by the National Health and Medical Research Council of Australia; SSaSS ClinicalTrials.gov number, NCT02092090.).

Protocol for the economic evaluation of the China Salt Substitute and Stroke Study (SSaSS).

INTRODUCTION: Cardiovascular diseases (CVDs) are the leading causes of death and disability worldwide. Reducing dietary salt consumption is a potentially cost-effective way to reduce blood pressure and the burden of CVD. To date, economic evidence has focused on sodium reduction in food industry or processed food with blood pressure as the primary outcome. This study protocol describes the planned within-trial economic evaluation of a low-sodium salt substitute intervention designed to reduce the risk of stroke in China. METHODS AND ANALYSES: The economic evaluation will be conducted alongside the Salt Substitute and Stroke Study: a 5-year large scale, cluster randomised controlled trial. The outcomes of interest are quality of life measured using the EuroQol-5-Dimensions and major adverse cardiovascular events. Costs will be estimated from a healthcare system perspective and will be sought from the routinely collected data available within the New Rural Cooperative Medical Scheme. Cost-effectiveness and cost-utility analyses will be conducted, resulting in the incremental cost-effectiveness ratio expressed as cost per cardiovascular event averted and cost per quality-adjusted life year gained, respectively. ETHICS AND DISSEMINATION: The trial received ethics approval from the University of Sydney Ethics Committee (2013/888) and Peking University Institutional Review Board (IRB00001052-13069). Informed consent was obtained from each study participant. Findings of the economic evaluation will be published in a peer-reviewed journal and presented at international conferences. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT02092090).

Environmental and Genetic Determinants of Major Chronic Disease in Beijing-Tianjin-Hebei Region: Protocol for a Community-Based Cohort Study.

Introduction: Personal lifestyle and air pollution are potential risk factors for major non-communicable diseases (NCDs). However, these risk factors have experienced dramatic changes in the Beijing-Tianjin-Hebei (BTH) region in recent years, and few cohorts have focused on identifying risk factors for major NCDs in this specific region. The current study is a large, prospective, long-term, population-based cohort study that investigated environmental and genetic determinants of NCDs in BTH areas. The results of this study may provide scientific support for efforts to develop health recommendations for personalized prevention. Methods: About 36,000 participants 18 years or older would be obtained by multistage, stratified cluster sampling from five cities for the baseline assessment. Participants underwent seven examinations primarily targeting respiratory and circulatory system function and filled out questionnaires regarding lifestyle behavior, pollutant exposure, medical and family history, medication history, and psychological factors. Biochemistry indicators and inflammation markers were tested, and a biobank was established. Participants will be followed up every 2 years. Genetic determinants of NCDs will be demonstrated by using multiomics, and risk prediction models will be constructed using machine learning methods based on a multitude of environmental exposure, examination data, biomarkers, and psychosocial and behavioral assessments. Significant spatial and temporal differentiation is well-suited to demonstrating the health determinants of NCDs in the BTH region, which may facilitate public health strategies with respect to disease prevention and survivorship-related aspects.

Association of long-term exposure to ambient particulate pollution with stage 1 hypertension defined by the 2017 ACC/AHA Hypertension Guideline and cardiovascular disease: The CHCN-BTH cohort study.

BACKGROUND: Evidence regarding the effects of ambient air pollution on new stage 1 hypertension defined by the 2017 ACC/AHA Hypertension Guideline remains sparse. OBJECTIVES: To investigate the association of long-term exposure to ambient PM2.5 with stage 1 hypertension and to explore the mediating and modifying effects of PM2.5 on cardiovascular disease (CVD). METHODS: A total of 32,135 participants aged 18-80 years were recruited in 2017. The three-year (2014-2016) average PM2.5 concentrations were assessed by a spatial statistical model. Blood pressure (BP) was divided into four categories according to the 2017 ACC/AHA Hypertension Guideline: normal BP (SBP<120 mmHg and DBP<80 mmHg), elevated BP (SBP 120-129 mmHg and DBP<80 mmHg), stage 1 hypertension (SBP 130-139 mmHg or DBP 80-89 mmHg), and stage 2 hypertension (SBP≥140 mmHg or DBP≥90 mmHg or taking antihypertensive medications). The associations of PM2.5 with BP categories were estimated by two-level generalized linear mixed models. Analyses stratified by age, mediation and interaction analyses of PM2.5 and stage 1 hypertension with CVD were performed. RESULTS: We detected a positive significant association between long-term exposure to PM2.5 and stage 1 hypertension. Compared to normal BP, the OR was 1.05 (95% CI: 1.02, 1.08) per 10 µg/m3 increase in PM2.5. The association was stronger than that of elevated BP but weaker than that of stage 2 hypertension. Stage 1 hypertension only partially mediated the association between PM2.5 and CVD, and the mediation proportions ranged from 1.55% to 11.00%. However, it modified the association between PM2.5 and CVD, which was greater in participants with stage 1 hypertension (OR: 1.66; 95% CI: 1.43, 1.93) than in participants with normal BP (OR: 1.32; 95% CI: 1.11, 1.57), with Pinteraction<0.001. In the analysis stratified by age, the above associations were age-specific, and significant associations were only observed in the young and middle-aged (<60 years) groups. CONCLUSIONS: Long-term exposure to ambient PM2.5 was significantly associated with stage 1 hypertension. This earlier stage of hypertension may be a trigger BP range for adverse effects of air pollution in the development of hypertension and CVD, especially in young and middle-aged individuals.

Elevated lipoprotein(a) and risk of coronary heart disease according to different lipid profiles in the general Chinese community population: the CHCN-BTH study.

BACKGROUND: To evaluate the contributions of elevated lipoprotein(a) [Lp(a)] to the risk of coronary heart disease (CHD) in the general Chinese community population according to different lipid profiles. METHODS: We recruited individuals aged over 18 years from the baseline survey of the Cohort Study on Chronic Disease of Communities Natural Population in Beijing, Tianjin and Hebei (CHCN-BTH) using a stratified, multistage cluster sampling method. Data were collected through questionnaire surveys, anthropometric measures and laboratory tests. Restricted cubic spline (RCS) functions, multivariate logistic regression, sensitivity analyses and stratified analyses were used to evaluate the association between Lp(a) and CHD. RESULTS: A total of 25,343 participants were included, with 1,364 (5.38%) identified as having CHD. Elevated Lp(a) levels were linearly related to an increased risk of CHD (Poverall-association<0.0001 and Pnonlinear-association=0.8468). Multivariate logistic regression analysis indicated that subjects with Lp(a) ≥300 mg/L had a higher risk of CHD [OR (95% CI): 1.36 (1.17, 1.57)] than did individuals with Lp(a) <300 mg/L. Compared with individuals with Lp(a) <119.0 mg/L (<50th percentile), the ORs (95% CI) for CHD in the 51st-80th, 81st-95th and >95th percentiles were 1.07 (0.93, 1.23), 1.26 (1.07, 1.50) and 1.68 (1.30, 2.17), respectively (P for trend <0.0001). This association was also found among the subgroup of subjects without dyslipidemia, including those with normal total cholesterol (TC) (<6.2 mmol/L), triglycerides (TG) (<2.3 mmol/L), high-density lipoprotein cholesterol (HDL-C) (≥1.0 mmol/L) and low-density lipoprotein cholesterol (LDL-C) (<4.1 mmol/L). Elevated Lp(a) and dyslipidemia significantly contributed to a higher risk of CHD with synergistic effects. Stratified analyses showed that elevated Lp(a) concentrations were significantly associated with an increased risk of CHD in the subgroups of individuals who were noncurrent drinkers, overweight individuals, individuals with hypertension, individuals who engaged in moderate physical activity, those without diabetes mellitus and individuals in Beijing and Tianjin. CONCLUSIONS: Elevated Lp(a) concentrations were linearly associated with a higher risk of CHD in the general Chinese community population, especially in normolipidemic subjects. Both dyslipidemia and elevated Lp(a) independently or synergistically contributed to the risk of CHD. Our results suggest that more attention should be paid to the levels of Lp(a) in normolipidemic subjects, which may be an early predictor of CHD.

Association of chronic diseases with depression, anxiety and stress in Chinese general population: The CHCN-BTH cohort study.

Background Large-scale epidemiological surveys focusing on characteristic differences in psychological and physical health conditions in Chinese adults are lacking. Objective To investigate the association of noncommunicable chronic diseases (NCDs) with depression, anxiety and stress in the Chinese general population. Methods A total of 13784 participants were recruited from the baseline survey of the Cohort Study on Chronic Disease of Communities Natural Population in Beijing, Tianjin and Hebei (CHCN-BTH) from 2017 to 2019. Sociodemographic characteristics, lifestyle and NCDs were assessed via questionnaire. Stress, anxiety and depression were assessed by the Depression-Anxiety-Stress Scale (DASS-21). The relationship of NCDs with psychological symptoms was determined through logistic regression analysis. Results Multivariate logistic regression analysis revealed that the prevalence of stress (OR = 1.640; 95% CI: 1.381-1.949), anxiety (OR = 1.654; 95% CI: 1.490-1.837) and depression (OR = 1.460; 95% CI: 1.286-1.658) symptoms were all significantly higher in patients with NCDs. Multimorbidities were associated with a higher risk of stress (OR = 2.310; 95% CI: 1.820-2.931), anxiety (OR = 2.119; 95% CI: 1.844-2.436) and depression (OR = 2.785; 95% CI: 1.499-2.126) than single NCDs. A course of disease within 1 year or more than 5 years also was associated with a higher risk. Limitations The cross-sectional design could not examine the causal link between psychological symptoms and NCDs. Conclusion Psychological symptoms were more prevalent among individuals with NCDs in the Chinese general population. This study suggests that more attention should be paid to the mental health problems of patients with NCDs.

Feasibility and validity of using death surveillance data and SmartVA for fact and cause of death in clinical trials in rural China: a substudy of the China salt substitute and stroke study (SSaSS).

BACKGROUND: In rural China, mortality surveillance data may be an alternative to primary data collection in clinical trials; SmartVA (verbal autopsy) is also a potential alternative for endpoint adjudication. The feasibility and validity of both need to be assessed. METHODS: We used mortality data from the first 24 months of the China Salt Substitute and Stroke Study (SSaSS) trial and assessed the agreement between (1) mortality surveillance data and face-to-face visits for fact of death; (2) mortality surveillance data and SSaSS adjudication for causes of death; (3) SmartVA and SSaSS adjudication for causes of death; (4) cause-specific mortality fraction of different methods. Face-to-face visits and SSaSS adjudication were taken as reference methods. The agreement was measured by sensitivity, specificity and positive predictive value (PPV) across different 10th Revision of International Statistical Classification of Diseases chapters. RESULTS: One thousand three hundred and sixty-five deaths were included. Mortality surveillance data had 82% sensitivity for fact of death and 81% sensitivity for causes of death, with substantial variances across different disease types and reasonable quality for circulatory death (91% sensitivity and 94% PPV). The sensitivity of SmartVA for causes of death was 61%, with reasonable quality for deaths of external causes of morbidity (90% sensitivity). The leading causes of death from different sources were the same with some variances in the fractions. CONCLUSION: Using mortality surveillance data for fact of death in clinical trials need to account for under-reporting. A face-to-face visit to all participants at the completion of trials may be warranted. Neither mortality surveillance data nor SmartVA provided valid data source for endpoint events.

Associations of long-term exposure to ambient air pollution with cardiac conduction abnormalities in Chinese adults: The CHCN-BTH cohort study.

BACKGROUND: Evidence regarding the effects of long-term and high-level ambient air pollution exposure on cardiac conduction systems remains sparse. OBJECTIVES: To investigate the associations of long-term exposure to air pollution and cardiac conduction abnormalities in Chinese adults and explore the susceptibility characteristics. METHODS: In 2017, a total of 27,047 participants aged 18-80 years were recruited from the baseline survey of the Cohort Study on Chronic Disease of Communities Natural Population in Beijing, Tianjin and Hebei (CHCN-BTH). The three year (2014-2016) average pollutant concentrations were assessed by a spatial statistical model for PM2.5 and air monitoring stations for PM10, SO2, NO2, O3 and CO. Residential proximity to a roadway was calculated by neighborhood analysis. Associations were estimated by two-level generalized linear mixed models. Stratified analyses related to demographic characteristics, health behaviors, and cardiometabolic risk factors were performed. Two-pollutant models were used to evaluate the possible role of single pollutants. RESULTS: We detected significant associations of long-term air pollutant exposure with increased heart rate (HR), QRS and QTc, such that an interquartile range increase in PM2.5 was associated with 3.63% (95% CI: 3.07%, 4.19%), 1.21% (95% CI: 0.83%, 1.60%), and 0.13% (95% CI: 0.07%, 0.18%) changes in HR, QRS and QTc, respectively. Compared to the other pollutants, the estimates of PM2.5 remained the most stable across all two-pollutant models. Similarly, significant associations were observed between living closer to a major roadway and higher HR, QRS and QTc. Stratified analyses showed generally greater association estimates in older people, males, smokers, alcohol drinkers, and those with obesity, hypertension and diabetes. CONCLUSIONS: Long-term exposure to ambient air pollution was associated with cardiac conduction abnormalities in Chinese adults, especially in older people, males, smokers, alcohol drinkers, and those with cardiometabolic risk factors. PM2.5 may be the most stable pollutant to reflect the associations.

Smoking Prevalence, Patterns, and Cessation Among Adults in Hebei Province, Central China: Implications From China National Health Survey (CNHS).

As part of the China National Health Survey, the objective of this study was to explore the prevalence, patterns, and influencing factors of smoking, and understand reasons for smoking cessation among adults in Hebei Province, central China. Using a multi-stage stratified cluster sampling method, 6,552 adults (2,594 males) aged 20-80 were selected in 2017. Demographic, socioeconomic, and tobacco use information were collected by questionnaire interview. The prevalence of ever-smoking, current smoking, and ex-smoking was 28.94, 21.08, and 7.86%, respectively. Male participants had a much higher prevalence of ever-smoking and current smoking (67.39 and 48.77%) than females (3.74 and 2.93%). In male participants, the daily cigarette consumption was 16.61, and the mean age of smoking initiation was 20.95, decreasing with birth year (27.50 in people born before 1946 vs. 17.9 for those born after 1985, p for trend < 0.001). Over 40% of male ever-smokers initiated regular smoking before 20. Compared with never drinking, the ORs (95% CI) of ever-smoking for low, moderate, and high alcohol consumption in male participants were 1.44 (1.11-1.86), 2.80 (1.91-4.11), and 2.40 (1.72-3.33), respectively. Among 479 male ex-smokers, 50.94% stopped smoking because of illness and 49.06% by choice. Among male ex-smokers, hypertensive men were more likely to quit smoking than the normotensive individuals (OR: 1.48, 95% CI: 1.13-1.96). For CVD patients, this effect was estimated as 2.27 (95% CI: 1.56-3.30). This study revealed a high prevalence of ever-smoking, especially in men, in a representative population in central China. Health education focus on tobacco control could be integrated with alcohol consumption reduction to achieve additional benefit.

Interim effects of salt substitution on urinary electrolytes and blood pressure in the China Salt Substitute and Stroke Study (SSaSS).

The Salt Substitute and Stroke Study is an ongoing 5-year large-scale cluster randomized trial investigating the effects of potassium-enriched salt substitute compared to usual salt on the risk of stroke. The study involves 600 villages and 20,996 individuals in rural China. Intermediate risk markers were measured in a random subsample of villages every 12 months over 3 years to track progress against key assumptions underlying study design. Measures of 24-hour urinary sodium, 24-hour urinary potassium, blood pressure and participants' use of salt substitute were recorded, with differences between intervention and control groups estimated using generalized linear mixed models. The primary outcome of annual event rate in the two groups combined was determined by dividing confirmed fatal and non-fatal strokes by total follow-up time in the first 2 years. The mean differences (95% CI) were -0.32 g (-0.68 to 0.05) for 24-hour urinary sodium, +0.77 g (+0.60 to +0.93) for 24-hour urinary potassium, -2.65 mmHg (-4.32 to -0.97) for systolic blood pressure and +0.30 mmHg (-0.72 to +1.32) for diastolic blood pressure. Use of salt substitute was reported by 97.5% in the intervention group versus 4.2% in the control group (P<.0001). The overall estimated annual event rate for fatal and non-fatal stroke was 3.2%. The systolic blood pressure difference and the annual stroke rate were both in line with the statistical assumptions underlying study design. The trial should be well placed to address the primary hypothesis at completion of follow-up.

A town level comprehensive intervention study to reduce salt intake in China: protocol for a cluster randomised controlled trial.

INTRODUCTION: Salt intake in China (≈12 g/day) is more than twice the upper limit recommended by the WHO (5 g/day). To reduce salt intake, Action on Salt China (ASC) was launched in 2017. As one of four randomised controlled trials (RCTs) in the ASC programme, a comprehensive intervention study was designed to test whether all the components of the interventions adopted by other RCTs are acceptable, scalable and effective when provided to a region in the real world. METHODS AND ANALYSIS: Using a cluster RCT design, 2688 participants were selected from 48 towns (clusters) in 12 counties in 6 provinces and assigned to the intervention group or the control group. Randomisation was performed after the baseline survey was completed. Information on salt-related knowledge, attitude and practice (KAP), blood pressure and 24-hour urinary sodium were collected. The intervention includes government engagement, health education and other intervention components targeting restaurants, home cooks and primary school students and their families that have been used in other RCTs. The control group will not receive the intervention. The project will be followed up for 2 years, with the intervention being carried out for the first year only. The primary outcome is salt intake measured by 24-hour urinary sodium excretion after 1 year. The secondary outcomes are the long-lasting effectiveness on salt intake and blood pressure measured by the same method, as well as salt-related KAP and blood pressure at the 1-year and 2-year follow-ups. Process evaluation and health economics analysis will be conducted as well. ETHICS AND DISSEMINATION: The study was reviewed and approved by the Institutional Review Board of the National Center for Chronic and Noncommunicable Disease Control and Prevention, the Chinese Center for Disease Control and Prevention, and Queen Mary Research Ethics Committee. Results will be disseminated through presentations, publications and social media. TRIAL REGISTRATION NUMBER: ChiCTR1800018119.

Prevalence and risk factors for pterygium: a cross-sectional study in Han and Manchu ethnic populations in Hebei, China.

AIMS: To investigate the prevalence, ethnic differences and associated risk factors for pterygium in Han and Manchu populations aged 40-79 years in Hebei province, China. DESIGN: Cross-sectional study, as a part of the China National Health Survey. SETTING: Hebei province, China. PARTICIPANTS: A multistage cluster sampling method with urbanisation level-based stratification was used to select participants for this study. A total of 4591 individuals over 40 years were recruited for this study. Inclusive criteria: (1) residents who had been living in Hebei for more than 1 year; (2) Han individuals with both parents being Han, or Manchu individuals with both parents being Manchu; (3) underwent ophthalmic examinations and (4) information in the questionnaire was complete. MAIN OUTCOME MEASURES: Multiple logistic regression analysis was used to evaluate the association between pterygium prevalence and factors of interest. RESULTS: A total of 3790 individuals (2351 Hans and 1439 Manchus) met the study criteria, of which 248 were diagnosed with pterygium (6.5%). There was no significant difference between the prevalence rates in Hans (6.2%) and Manchus (7.2%) (p=0.232). Multivariate analysis revealed that the risk factors for grade 2 or higher pterygium were increasing age (p<0.001) and rural residence (OR 1.83; 95% CI 1.11 to 3.02; p=0.018), while the protective factors include gender (female) (OR 0.58; 95% CI 0.37 to 0.88; p=0.011), cigarette smoking (OR 0.53; 95% CI 0.34 to 0.83; p=0.005) and myopia (OR 0.50; 95% CI 0.33 to 0.77; p=0.002). Premature menopause (OR 2.66; 95% CI 1.05 to 6.72; p=0.038) increased the risk of grade 2 or higher pterygium in females, while higher high-density lipoprotein (HDL) (OR 1.94; 95% CI 1.08 to 3.47; p=0.027) was a risk factor of grade 2 or higher pterygium in males. CONCLUSION: The overall prevalence of pterygium in Han and Manchu population in Hebei, China was approximately 6.1%. There were no differences in the prevalence of pterygium between Hans and Manchus, and the race was not a risk factor. This is the first study to report on the positive association between premature menopause and pterygium in females and between higher HDL levels and pterygium in males.

Spot urine samples compared with 24-h urine samples for estimating changes in urinary sodium and potassium excretion in the China Salt Substitute and Stroke Study.

Background: The capacity of spot urine samples for detecting changes in population sodium and potassium excretion is unclear. Methods: Changes in urinary sodium and potassium excretion, over a 6-month to 2-year interval, were measured from 24-h urine samples and estimated from spot urine samples using several published methods in 3270 Chinese. Additional estimates were made by multiplying individual spot sodium and potassium concentrations by a single estimated 24-h urine volume derived from external data. Results: The measured difference in 24-h urinary excretion between intervention and control groups was -0.35 g (95% CI: -0.68 to -0.02; P = 0.039) for sodium and 0.66 g (95% CI: 0.52 to 0.80; P < 0.001) for potassium, based upon 24-h urine samples. The corresponding estimates of sodium differences for the Tanaka (-0.06 g), Kawasaki (-0.09 g), Intersalt without potassium (-0.09 g) and Intersalt with potassium (-0.14 g) equations were all smaller and identified no reduction in sodium excretion (all P > 0.10). The estimates were -0.65 g for sodium and 1.11 g for potassium using individual spot urine concentrations and an externally derived standard urine volume (both P < 0.01). Conclusions: The published equations were unable to detect the differences in sodium excretion measured by 24-h urine samples. A method based upon spot urine electrolyte concentrations and a standard urine volume may offer an alternative approach to measuring differences in sodium and potassium excretion between population groups without requiring 24-h urine, but will need further investigation.

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.

Use of Smartphone for Verbal Autopsy.

Traditionally, verbal autopsies (VA) are collected on paper-based questionnaires and reviewed by physicians for cause of death assignment, it is resource intensive and time consuming. The Population Health Metrics Research Consortium VA questionnaires was made available on an Android-based application and cause of death was derived using the Tariff method. Over one year, all adult deaths occurring in 48 villages in 4 counties were identified and a VA interview was conducted using the smartphone VA application. A total of 507 adult deaths were recorded and VA interviews were conducted. Cardiovascular disease was the leading cause of death (35.3%) followed by injury (14.6%) and neoplasms (13.5%). The total cost of the pilot study was USD28 835 (USD0.42 per capita). The interviewers found use of smartphones to conduct interviews to be easier. The study showed that using a smartphone application for VA interviews was feasible for implementation in rural China.