Study population
In our previous paper, we described the characteristics of the study in detail [8]. From January 2001 to August 2003, we enrolled residents older than 35 years in order to evaluate the prevalence rate, morbidity rate and historical process of CVD in villages of Liaoning Province in the Northeast area of China. The excluded criteria has been mentioned previously [12].
Pregnant subjects and those who had a mental disorder or malignant tumors were excluded in the present research. We asked 14016 eligible residents from different villages who aged more than 35 years to attend our research. Of the 14016 residents, 85.3% responded, agreed to participate and completed the research. This research was proved by the Ethics Committee of the Chinese Medical University (China Shen Yang, AF-SDP-07-1,0-01). We performed the research procedures following the ethically normative criteria. Participants’ welfare, medical plans and confidentiality agreements associated to their contact details have been informed ahead of the research starting. Then written consent form was given to the participants. In the present study report, we only used the data from participants who were older than 65 years, so the final sample count was 6837 (3150 men and 3687 women).
Data Collecting and Measurements
Both cardiologist and nurses with skilled training will sit face to face with study subjects during the interview and retrieved data using a standardized questionnaire. An organized training meeting from training center was held to qualified investigators [8, 12]. After the training, trainers will have a test to figure out whether they are qualified as investigators to collect data. More guidance and backed up will be supplied to them during the investigation. The specific aspects acquired in the interview has been mentioned before, like family annual income, food habits, socioeconomic characteristics [8, 12]. The central steering committee and quality control committee are responsible to guide this study. In this research, we evaluated subject’s education situation, sleep during and annual family income and the specific categories have been described. We also estimated subjects’ daily frequency of beans or soy products consumption and tea consumption as previously reported [8]. As for blood pressure (BP) measurement, we used a standard protocol as many guidelines have recommended. Participants should be at rest for at least five minutes and without caffeinated drinks or exercise before BP measurement. Omron Healthcare automatic electronic sphygmomanometers (HEM-907; Omron Healthcare, Kyoto, Japan) were used to measure participants BP. We used the average of three times BP measurements in all the analyses. While measuring height and weight, we asked subjects to wear light clothes and take off shoes. We took down the measurement of height and weight to the accuracy of 0.1cm and 0.1 kg. Subjects’ waist circumference (WC) were also measured with nonelastic tape at the umbilicus (0.1cm). BMI= body weight (kg)/ height (m) 2.
Participants were required to fast at least twelve hours and taken fasting blood specimens in the morning. As previous described, we used enzymatic analysis to exam total cholesterol (TC), triglycerides (TGs), fasting blood glucose (FPG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) by an automatic biochemical analyzer and biochemical indicators [8, 9]. Technician calibrated the laboratory equipment before using and the specimen analyses were repeated by using blind specimens.
We took M-mode measurements at end diastole and end systole according to the American Society of Echocardiography (ASE) recommendations [13]. The detail of the procedures has been reported previously [8]. Average five consecutive cardiac cycles were used to calculate the echocardiographic data. A single cardiologist read those images under the circumstance that without knowing the subjects’ clinical characteristics.
Definitions
At present, there is no uniform definition of HHcy. According to the WHO standard, the average level of Hcy for healthy adults is 5–15 μmol/L, with an Hcy level >15 μmol/L representing HHcy [14]. MetS was diagnosed according to the modified NCEP ATP III criteria. At least 3 or more of the following 5 components were needed to diagnose MetS:
Components
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Criteria
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Elevated WC
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≥ 90 cm (Male);
≥ 80 cm (Female)
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Elevated TG
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> 150 mg/dL (1.7 mmol/L)
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Reduced HDL-C
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< 40 mg/dL or 1.04 mmol/L (Male)
< 50 mg/dL or 1.29 mmol/L (Female)
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Hypertension or elevated BP
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≥130/85 mmHg
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Diabetes or elevated FPG
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≥ 5.6 mmol/L
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WC ≥ 88 cm for females and WC ≥ 102 cm for males was defined as abdominal obesity [16].
TC ≥ 6.21 mmol/L (240 mg/dL) means high TC while high LDL-C was diagnosed as the concentration of LDL-C ≥ 4.16 mmol/L (160 mg/dL). According to the WHO criteria, FPG ≥ 7 mmol/L (126 mg/dL) and/or being on treatment for diabetes was diagnosed as diabetes [17].
The LVM was calculated according to the formula of Devereux and Reichek [18]:
LVM (g)=1.04×[(LV end-diastolic dimension (LVEDD)*+end-diastolic interventricular septum thickness (IVSd)#+end-diastolic LV posterior wall septum thickness (PWd)$)3-(LVEDD)3]-13.6
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* LVEDD is the end-diastolic LV internal diameter; # IVSd is the ventricular septal thickness; $ PWd is the posterior LV wall thickness
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It was indexed by both body surface area (LVMI) and by height raised to a power of 2.7 (LVMH2.7), as suggested by De Simone et al. [18].
We used cutoff point of 51 gm-2.7 in either sex to separate normal left ventricular thickness from LVH due to its value was related to prognostics [19]. In line with the ASE recommendations, high LVMI was defined as LVMI larger than 115 g/m2 for male patients and larger 95 g/m2 for female patients. Participants who were never smoking or drinking defined as never smokers or never drinker and who are smoking presently were defined as current smokers or current drinkers. Physical activity was evaluated using questions that have been described in many previous studies which were similar to those used and validated in the “Seven Countries Study” [20].
Statistical Analysis
Continuous variables which were expressed using standard deviations and averages and categorical variables which were expressed using percentages and numbers were calculated using a nonparametric test, ANOVA, Student’s t-test, or the χ2-test, as appropriate, to assess the differences among diverse groups. Multivariate logistic regression analysis was used to estimate the independent elements correlated with cardiac metabolic syndrome. The corresponding 95% confidence intervals (CIs) and odds ratios (ORs) were calculated to infer the possible relationship. Basic multivariate logistic regression models were used to estimate the relationship among different social hierarchies. All statistical analyses were carried out using SPSS version 17.0 software (SPSS Inc., Chicago, IL, US), and P values <0.05 were deemed to be of statistical value.