title: Methodological issues for a large-scale intervention trial of lifestyle modification: Interim assessment of the high-risk and population strategy for occupational health promotion (HIPOP-OHP) study.
abstract: OBJECTIVE
  To clarify the methodological issues for the High-risk and population Strategy for Occupational Health Promotion Study (HIPOP-OHP study), which is a 4-year non-randomized control trial, an interim assessment of male participants was performed 3 years after the baseline survey.
  
  
  METHODS
  We had approximately 2,500 and 4,000 participants in the intervention and control groups, respectively. The population measures and prevalence of risk factors at each year, and between the baseline and 4th examinations were compared between the two groups. The personal trends of returning participants who were in the study at the 1(st) and 4(th) examinations were also evaluated.
  
  
  RESULTS
  During the 3 years, an increase in serum HDL cholesterol (2.7 mg/dl), and a reduction in the prevalence of hypertriglycemia detected with fasting blood samples (3.6%) and current smokers (5.4%) were observed in the intervention group. The mean HDL cholesterol level was significantly higher in the intervention group than in the control group at the 4th examination, reversed from the baseline survey. The serum non-HDL cholesterol level was significantly increased only in the control group. There was also a significant increase in the prevalence of hypertriglycemia nad high plasma glucose detected with fasting blood samples in the control group. The return participation rate after 3 years was 72.2% for the intervention group and 74.9% for the control group. The above-mentioned changes for risk factors were mainly due to returning participants at each examination.
  
  
  CONCLUSIONS
  These interventional methods may be effective in improving overall cardiovascular risk factors in the population. However, the low return participation rate will dilute the effect of the intervention.
authors: Department of Health Science, Shiga University of Medical Science Seta, Tsukinewa-cho, 520-2192, Otsu, Japan, tokamura@belle.saiga-med.ac.jp.
authors: Tomonori
authors: T
authors: Okamura
authors: Taichiro
authors: T
authors: Tanaka
authors: Toru
authors: T
authors: Takebayashi
authors: Hideaki
authors: H
authors: Nakagawa
authors: Hiroshi
authors: H
authors: Yamato
authors: Katsushi
authors: K
authors: Yoshita
authors: Takashi
authors: T
authors: Kadowaki
authors: Akira
authors: A
authors: Okayama
authors: Hirotsugu
authors: H
authors: Ueshima