The Ohsaki Cohort 2006 Study: design of study and profile of participants at baseline.

BACKGROUND: Large-scale cohort studies conducted in Japan do not always include psychosocial factors as exposures. In addition, such studies sometimes fail to satisfactorily evaluate disability status as an outcome. METHODS: This prospective cohort study comprised 49 603 (22 438 men and 27 165 women) community-dwelling adults aged 40 years or older who were included in the Residential Registry for Ohsaki City, Miyagi Prefecture, in northeastern Japan. The baseline survey, which included psychosocial factors, was conducted in December 2006. Follow-up of death, immigration, cause of death, cancer incidence, and long-term care insurance certification was started on 1 January 2007. RESULTS: The response rate was 64.2%. In general, lifestyle-related conditions in the study population were similar to those of the general Japanese population; however, the proportion of male current smokers was higher in the cohort. The association between age and the proportion of those reporting psychological distress showed a clear U-shaped curve, with a nadir at age 60 to 69 years in both men and women, although more women were affected by such distress than men. The proportion of those who reported a lack of social support was highest among those aged 40 to 49 years. Most men and women surveyed did not participate in community activities. Among participants aged 65 years or older, 10.9% of participants were certified beneficiaries of the long-term care insurance system at baseline. CONCLUSIONS: The Ohsaki Cohort 2006 Study is a novel population-based prospective cohort study that focuses on psychosocial factors and long-term care insurance certification.

Factors associated with psychological distress in a community-dwelling Japanese population: the Ohsaki Cohort 2006 Study.

BACKGROUND: In Asia, there has been no population-based epidemiological study using the K6, a 6-item instrument that assesses nonspecific psychological distress. METHODS: Using cross-sectional data from 2006, we studied 43,716 (20,168 men and 23,548 women) community-dwelling people aged 40 years or older living in Japan. We examined the association between psychological distress and demographic, medical, lifestyle, and social factors by using the K6, with psychological distress defined as 13 or more points out of a total of 24 points. RESULTS: The following variables were significantly associated with psychological distress among the population: female sex, young and old age, a history of serious disease (hypertension, diabetes mellitus, stroke, myocardial infarction, or cancer), current smoking, former alcohol drinking, low body mass index, shorter daily walking time, lack of social support (4 of 5 components), and lack of participation in community activities (4 of 5 components). Among men aged 40 to 64 years, only "lack of social support for consultation when in trouble" and a history of diabetes mellitus remained significant on multivariate analysis. Among men aged 65 years or older, age was not significantly associated with psychological distress, and the significant association with current smoking disappeared on multivariate analysis. Among women aged 40 to 64 years, a history of stroke was not associated with psychological distress. Among women aged 65 years or older, the significant association with current smoking disappeared on multivariate analysis. CONCLUSIONS: A number of factors were significantly associated with psychological distress, as assessed by the K6. These factors differed between men and women, and also between middle-aged and elderly people.

Time spent walking and risk of colorectal cancer in Japan: the Miyagi Cohort study.

Higher levels of physical activity have been consistently associated with a lower risk of colon cancer in earlier epidemiological studies. The specific benefits of walking, however, remain relatively unexplored. In 1990, 20 519 men and 21 469 women in Japan completed a self-administered questionnaire including a question on time spent walking per day. During 7 years of follow-up, 260 cases of colorectal cancer were documented in 305 790 person-years. We used the Cox proportional hazards regression model to estimate the relative risk of incident cancer (colorectal, colon, and rectal) according to three levels of walking. Time spent walking was inversely associated with risk of colorectal cancer incidence in men. Compared with men who walked 0.5 h or less per day, the multivariate relative risks were 1.06 (95% confidence interval 0.72-1.57) for men who walked between 0.5 and 1 h per day, and 0.57 (95% confidence interval 0.38-0.83) for men who walked 1 h or more per day (P for trend=0.003). Time spent walking per day was associated with a lower risk of colon cancer in Japanese men but not in women, and there was no association between time spent walking and the risk of rectal cancer.

Walking and mortality in Japan: the Miyagi Cohort Study.

BACKGROUND: Although many studies in western populations demonstrated that time spent walking was associated with a reduced risk of all-cause mortality, data on Japanese has been sparse. METHODS: In 1990, 20,004 men and 21,159 women in Miyagi Prefecture in rural northern Japan (40-64 year of age) completed a self-administered questionnaire including a question on time spent walking. Cox regression was used to estimate relative risk (RR) of mortality according to three levels of walking (30 minutes or less, between 30 minutes and one hour, and one hour or more), with adjustment for age, education, marital status, past history of diseases, smoking, drinking, body mass index, and dietary variables. During 11 years of follow-up, 1,879 subjects had died. RESULTS: Time spent walking was inversely associated with risk of all-cause mortality: compared with men and women who walked one hour or more per day, multivariate RR (95% confidence intervals) was 1.06 (0.95-1.19) for subjects who walked between 30 minutes and one hour per day, and 1.16 (1.04-1.29) for subjects who walked 30 minutes or less per day (P for trend=0.007). Shorter duration of walking was associated with increased mortality among men who were never smokers (P for trend=0.081) and past smokers (P for trend=0.026), but not among currently smoking men (P for trend=0.751). We observed similar effect modification for women. CONCLUSIONS: Time spent walking was associated with a reduced risk for all-cause mortality, especially among nonsmoking men and women.

Health practices and mortality in Japan: combined effects of smoking, drinking, walking and body mass index in the Miyagi Cohort Study.

BACKGROUND: Evidence is limited regarding the association between the combinations of multiple health practices and mortality. METHODS: In 1990, 28,333 men and women in Miyagi Prefecture in rural northern Japan (40-64 year of age) completed a self-administered questionnaire. A lifestyle score was calculated by adding the number of high-risk practices (smoking, consuming > or = 22.8 g alcohol/d, walking < 1 hr/d, body mass index < 18.5 or > or = 30.0). Cox regression was used to estimate relative risk (RR) of mortality according to the lifestyle score, with adjustment for age, education, marital status, past history of diseases, and dietary variables. During 11 years of follow-up, 1,200 subjects had died. RESULTS: We observed linear increase in risk of death associated with increasing number of high-risk practices: compared with men who had no high-risk practices, multivariate RRs for men who had 1 to 4 practices were 1.20, 1.66, 1.94, and 3.96, respectively (P for trend<0.001), and corresponding RRs for women were 1.31, 2.14, 3.98, 5.56, respectively (P for trend<0.001). A unit increase in the number of high-risk practices corresponded to being 2.8 and 4.8 years older for men and women, respectively. CONCLUSIONS: In this prospective cohort study of middle-aged men and women in rural Japan, a larger number of high-risk practices was associated with linear increase in risk of all-cause mortality.