Study design and participants
The study population was selected from the Henan Rural Cohort Study, which is a prospective study of chronic non-communicable disease with a large sample of rural people established in Henan Province, China during 2015–2017.In brief, the cohort used a multistage stratified cluster sampling method to recruit participantsaged from 18 to 79 years. With a response rate of 93.7%, 39259 individuals were included in the cohort study. Detailed information of the cohort has been described elsewhere30. The participants were excluded if they: (1) were diagnosed with CHD (n=1734); (2) were diagnosed with Stroke (n=2642); (3)were missed information needed in the present study excluded (n=124). Finally, 35018 adults were ultimately included in the study. Before the study commenced, participants were informed of the study’s purpose, health benefits, and potential hazards. Participants were required to provide informed consent and both the researchers and respondents agreed to use the data for scientific research purposes only.
Data collection
A standard questionnaire was conducted by well-trained research staffby face to face interviews to obtain information regarding participants’ demographic characteristics, lifestyles, Food Frequency Questionnaire (FFQ),individual history of diseasesand medication. Demographic characteristics included age, gender, educational level (elementary school or below, junior high school and high school or above), marital status (married/cohabitating and unmarried/divorced/widowed), per capita monthly income (< 500, 500~ and ≥ 1000 renminbi (RMB)).
Lifestyle factorsincluded smoking (current smoker, non-current smoker), drinking (current drinking, non-current drinker) and physical activity. International Physical Activity Questionnaire (IPAQ 2001) was used to assess the levels of physical activity31. The FFQ, covered questions about thirteen main food groups, including staple foods, livestock, poultry, fish, eggs, dairy, fruits, vegetables, beans, nuts, pickles, cereal and animal oil, which based on the Dietary Guidelines for Chinese Residents and the eating habits of Henan people.Participants were asked generally about the frequency (daily, weekly, monthly, yearly, or never) and amount (in liang (50 g)) of their consumption of each food or food group in the past 12 months. Previous studies have shown that the FFQ has good reproducibility and validity32. Individual history of disease and medication were self-reported by the participants, including CVD (coronary heart disease, myocardial infarction, stroke, or heart failure), hypertension, diabetes mellitus, hyperlipidemia, and the use of antihypertensive, cholesterol-lowering, or glucose-lowering medications.
Weight and height were measured twice in light clothing with shoes offand recorded to the nearest 0.1kg and 0.1cm respectively and we calculated the average of the two measures. Body mass index (BMI) was computed as body weight (kg) divided by height square (m2) based on the measurement.WC was also measured twice with a standard tape around the waist about 1 cm above the navel and parallel to the ground. Blood pressure was measured three times by electronic sphygmomanometer (Omron HEM-7071A, Japan) in the right arm of sitting position after at least 5 min rest. There were 30s intervals between the three measurements.
The venous blood samples were collected from subjects after overnight fasting for at least 8 hours and stored in -80°C cryogenic refrigerator before analysis. The fasting blood glucose (FBG) was analyzed with via glucose oxidative method (GOD-PAP) by ROCHE Cobas C501 automatic biochemical analyzer30. Total cholesterol, triglyceride, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were measured by Roche Cobas C501 automatic biochemical analyzer.
Definitions
Tracking disease was easy because all respondents were covered by the New Rural Cooperative Medical System (NRCMS) and each participant had a unique medical insurance card number and ID. NRCMS medical records reviews of CVD were confirmed by rural doctor after self-reporting the history of CVD, and further determined by the outcome committee which is composed of a physician, an endocrinologist, a cardiologist, and an epidemiologist according to standardization recommended by World Health Organization criteria3334.
Smoking status was classified into current smoker who smoked more than one cigarette per day in the past six months and non-current smoker including ever smoker and never smoker. Alcohol drinking status was categorized into current drinking who consumed alcoholic drinks for twelve or more times in the past one year, whether spirits, beer, wine or other forms of alcoholic beverage, and non-current drinker including ever drinker and never drinker.WC < 90 cm for men and WC <80 cm for women were classified as normal waist circumference, and WC ≥ 90 cm for men and WC ≥ 80 cm for women were classified as abdominal obesity.
Ideal Cardiovascular Health metrics
According to the AHA definitions of ideal cardiovascular health(ICH)8, each of the 7 cardiovascular health metrics (smoking, physical activity, BMI, diet, total cholesterol, blood pressure and fasting plasma glucose) was categorized as ideal and non-ideal, respectively. ICH metrics were as follows: ideal smoking status, never smoker; ideal BMI, BMI < 25 kg/m2; ideal physical activity (PA), PA ≥ 150 min/wk of moderate intensity or ≥ 75 min/wk of vigorous intensity or ≥ 150 min/wk of moderate-vigorous intensity combination; ideal diet, ≥4 components; ideal total cholesterol (TC), TC < 5.18 mmol/L untreated; ideal blood pressure (BP), BP <120/< 80 mm Hg untreated, and ideal fasting plasma glucose (FPG), FPG < 5.6 mmol/L untreated. Furthermore, ICH was defined according to the American Heart Association’s 2020 Strategic Impact Goals as follows: the simultaneous presence of 4 ideal health behaviors (ideal smoking status, ideal BMI, ideal PA, and ideal diet) and 4 ideal health factors (ideal smoking status, ideal TC, ideal BP, and ideal FPG) in the absence of a history of cardiovascular disease.
We made some adaptations as appropriate for the healthy diet score. Ideal diet was defined as healthy diet score ≥ 4 components35 (fruits and vegetables ≥ 500 g/d; fish ≥ 200 g/week; soybean products ≥ 125 g/d; red meat < 75 g/d; drinking tea).
Statistical analysis
All analyses were performed separately for men and women. Continuous variables presented as mean ± SD were compared by using the t-test or analysis of variance, while categorical variables presented as numbers and proportions were compared by using chi-square test. The prevalence was standardized by using the direct method according to the Chinese Population Census 2010.We calculated the ICH scores by summing the total number of ideal metrics for each participant, ranging from 0 to 7, and ICH scores was further categorized into Non-CVH (0–4 scores) and Ideal CVH (5–7 scores) based on the total number of ideal indices. Ideal health behaviors (IHB) scores was calculated by summing the total number of IHB metrics ranging from 0 to 4, and IHB scores was further categorized into Non-HB (0–3 scores) and Ideal HB (4 scores). Ideal health factors (IHF) scores was calculated by summing the total number of IHF metrics ranging from 0 to 4, and IHF scores was further categorized into Non-HF (0–3 scores) and Ideal HF (4 scores) The association between socioeconomic factors and the prevalence of Ideal CVH, Ideal HB and Ideal HF were estimated by the multivariable logistic regression models, and were shown by odds ratio (OR) and 95% confidence interval (CI). All selected characteristics were included in multivariable logistic regression models. Besides, the three indices including age groups, educational attainment and per capita monthly income were taken as continuous variables to explore whether there was a linear trend of ORs. A p-value less than 0.05 (two tailed) was applied to assess the statistical significance. Statistical analyses were performed by SPSS software V.26.0 and R version 3.6.3.