The High-risk and Population Strategy for Occupational Health Promotion (HIPOP-OHP) study: study design and cardiovascular risk factors at the baseline survey

In order to establish the methodology of a population strategy for improving cardiovascular risk factors, we have planned the High-risk and Population Strategy for Occupational Health Promotion Study (HIPOP-OHP study). This study is a nonrandomized control trial in approximately 6500 participants in six intervention and six control companies. Our population strategy is based on three factors, nutrition, physical activity, and smoking. For each factor, a researcher's working team was organized and has been supporting the intervention. A standardized method to obtain comparable data has also been established. In the baseline survey, urinary sodium excretion in male subjects was higher, and urinary potassium excretion was lower in both genders in the intervention group compared to the control group. The prevalence of hypertension for both genders was also higher in the intervention group. Male subjects in the intervention group had higher serum total cholesterol than controls, while high-density lipoprotein cholesterol was lower in both genders in the intervention group compared to the control group. These differences were reflected by our finding that the predicted relative risk of coronary heart disease for male subjects was significantly higher in the intervention group (relative risk, RR: 1.17; 95% confidence interval, 95% CI.: 1.09, 1.25) and significantly lower in the control group (RR: 0.93; 95% CI.: 0.89, 0.98) compared to a model Japanese population. Similar results were observed in the female subjects. Taken together, these findings indicate that it is possible to compare trends of predicted relative risk for coronary heart disease between two groups.