Study design
The Ministry of Health, Labour and Welfare (MHLW) in Japan started the “Specific Health Check-up Project” nationally in 2008. This study was one part of the project, which was implemented in Soka City in Saitama Prefecture, Japan, with a population of about 233,000 [20, 21].
The present study employed a non-randomized controlled trial design. The program was provided from 2008 to 2010, including a 6-month intervention program and an 18-month follow-up program.
Participants
About 50,000 residents aged from 40–74 were invited to receive a health check-up. As shown in Figure 1, 12,961 residents aged 40–75 years old underwent health check-ups in 2008 and completed the baseline lifestyle questionnaire. Of these 12,961 subjects, 1,983 were selected for the study according to the following inclusion criteria [22], which were separated into two steps: (1) waist circumferences of the subjects as follows: ①waist circumference > =85 cm for males,> = 90 cm for females; ②waist circumference < 85 cm for males, <90 cm for females, and body mass index (BMI) > =25 kg/m2; (2) at least one of the following: hemoglobin (HbA1c) >5.2% (JDS, Japan Diabetes Society) (equal to >5.6% [NGSP, National Glycohemoglobin Standardization Program]) [23] or taking diabetes medication; triglycerides (TG) >150 mg/dl or high-density-lipoprotein cholesterol (HDL-C) <40 mg/dl or taking lipid-lowering medication; systolic blood pressure (SBP) > =130 mmHg or diastolic blood pressure (DBP) > =85 mmHg or taking hypertension medication; and having a history of smoking. The subjects who were taking diabetes, lipid-lowering and hypertension medication and were diagnosed as hypertension (SBP/DBP > = 140/90 mmHg), hyperlipidemia (LDL > =140 mg/dl or HDL <40 mg/dl or TG > = 150 mg/dl), diabetes (Fasting blood glucose > = 126 mg/dl or HbA1c > = 6.1% (JDS) (equal to > =6.5% [NGSP])) were advised to be seen by physicians, and were withdrawn from this study. The 1,983 subjects were informed about the program by direct mail and were then allocated into either the intervention or the control group according to the participants’ desire. The numbers of subjects in the intervention and control groups were 347(200 males and 147 females) and 1,636 (999 males and 637 females), respectively. After 6-month follow-up, 1,288 (251 in the intervention group and 1,037 in the control group) participants underwent the second health check-up and completed the lifestyle questionnaire. Finally, after the 18-month follow-up, 1,278 participants (238 in the intervention group and 1,040 in the control group) completed the final health check-up and lifestyle questionnaire in 2010 (Figure 1).
Risk factor measurements
All of the measurements were provided by medical institutions. Body weight and height were measured with no shoes and excess clothing removed on the same calibrated scale at the baseline, 6-month and 18-month follow-up. BMI was calculated as body weight (kg) divided by the square of the height (m2). Waist circumference was measured by nurses. SBP and DBP were measured using auto-manometers (Omron Co., Tokyo, Japan). Fasting blood samples from all subjects were obtained and TG, low-density lipoprotein cholesterol (LDL-C), HDL-C and HbA1c were measured at a laboratory (Saitama, Japan).
Subjects with overweight were defined as having a BMI > =25 kg/m2; subjects with hypertension risk were defined as having at least one of the following: SBP > =130 mmHg or DBP > =85 mmHg; subjects with dyslipidemia risk were defined as having at least one of the following: HDL-C <40 mg/dl, LDL-C > =140 mg/dl or TG > =150 mg/dl; subjects with diabetes risk were defined as having a HbA1c > 5.2% (JDS) (equal to >5.6% [NGSP]).
We used the Framingham risk score, which is based on age, TC, HDL-C, SBP and current smoking status, in order to establish risk scores [8]. HDL-C was classified into 4 levels (> = 60, 50–59, 40–49, <40 mg/dl). SBP was classified into 5 levels (<120,120-129,130-139,140-159,> = 160 mmHg). TC was calculated according to the Friedewald equation [24]. Estimated 10-year CHD risk was evaluated according to the Framingham risk score [8]. Moreover, we also used intermediate 10-year CHD risk with a definition of > =10% [8].
Assessment of lifestyle variables
Information on lifestyle factors such as smoking, drinking alcohol, dietary behaviors and physical activity, medical history and sleeping was obtained by a self-administered questionnaire at the baseline, 6 and 18 months.
Current smokers were defined as those who had been smoking for 6 months or had smoked over 100 cigarettes and were still smoking in the previous month. Drinking alcohol was indicated by the frequency of drinking and the amount of alcohol consumption per day. Dietary behaviors included eating speed, usual time for eating supper, eating snacks and skipping breakfast. Physical activity included regular exercise, daily physical activity and walking speed. Sleeping status was categorized as well or not well.
In this study, the preferable lifestyle behaviors were defined as follows: no smoking, exercise over 30 minutes and 2 times per week, walking or having physical activity over 1 hour every day, walking faster than their peers, not eating fast, not eating dinner less than 2 hours before sleeping, not eating snacks over 3 times every week, not skipping breakfast over 3 times every week, not drinking alcohol every day, drinking alcohol less than 22 g and sleeping well.
Intervention
All subjects in the intervention and control groups were given 3 health checkups and 3 lifestyle surveys at the baseline, 6-month follow-up, and 18-month follow-up.
The common program consisted of a lecture regarding the purpose of health promotion at the baseline and newsletters featuring general health information provided by local community health workers during the 18-month period.
For the intervention group, a comprehensive program consisting of a 6-month intervention was provided. The 6-month intervention program included individual counseling and group sessions, in addition to the common program.
Individual counseling
Individual counseling was conducted on the basis of the results of health check-ups and health assessment charts on lifestyle at the baseline (60 minutes per person).
Group sessions
The group sessions focused on nutrition and exercise (a total of 12 times of 60–120 minutes duration). The nutrition group sessions included talks, a lecture, cooking demonstrations and motivational interviewing. The exercise group sessions included aerobic exercises, stretching, walking and other exercises in a gym or local health or community center. The same program was provided during the daytime and at night for the convenience of participants. Through these approaches, participants were encouraged to set their own goals for lifestyle modification.
Other interventions by telephone and letter
The other interventions included contact by telephone (a total of 3 times of 5–15 minutes duration) and letter (a total of 3 times). Through telephone calls and letters, subjects were advised to attend the group sessions and motivated to change their lifestyle behaviors. Those who were absent from the group sessions were also followed up by telephone or letter to inquire about the reason. The changes in lifestyle behaviors among the subjects were also evaluated by questions over the telephone.
Statistical analysis
We selected lifestyle behaviors and cardiovascular disease risks as outcome measures in this study. Lifestyle behaviors included smoking, dietary behaviors, physical activity, drinking alcohol and sleeping. Cardiovascular disease risks included weight, BMI, waist circumference, SBP, DBP, HDL-C, LDL-C, TG and HbA1c.
Baseline cardiovascular disease risk and lifestyle behavior differences were analyzed by Student’s t-test for continuous variables, Mann–Whitney test for nonparametric variables and Chi-squared test for categorical variables.
The mean differences in changes in cardiovascular disease risk factors at 6 and 18 months between the intervention and control groups were assessed by covariance analysis adjusted for the baseline value, age, sex and intervention times. Comparisons of lifestyle behaviors at 6 and 18 months between the intervention and control groups were conducted by multiple logistic regression analysis adjusted for the baseline category, age and sex. The odds ratios (OR) and 95% confidence interval (95% CI) were used to indicate the relative risk ratio between the intervention and control groups. In addition, we determined the probability of risk in subjects with overweight, hypertension risk, dyslipidemia risk, diabetes risk, metabolic syndrome and 10-year CHD risk by multiple logistic regression analysis adjusted for the baseline category, age, sex and intervention times. All statistical analyses were performed using an assumed type I error rate of 0.05. Statistical analyses were performed using SPSS Statistics 20.0 for Windows (SPSS Japan Inc., Tokyo, Japan).
Ethical consideration
Ethical approval was given by the ethics committee at Dokkyo Medical University (No2057).