Fumiya Tanji

Association of marital status with the incidence of suicide: A population-based Cohort Study in Japan (Miyagi cohort study)

BACKGROUND Marital status is one of the most frequently replicated predictors of suicide. The purpose of this study was to examine the effect of marital status on the risk of suicide by gender, using a large population-based cohort in Japan. METHODS The Miyagi cohort study was a population-based, prospective cohort study of Japanese adults aged between 40 and 64 years. Between June and August 1990, 47,604 participants residing in 14 municipalities of Miyagi Prefecture, Japan, completed a questionnaire on various health-related lifestyles, including marital status. During 18 years of follow-up, 146 of the participants committed suicide. We used the Cox proportional hazards regression model to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) for suicide mortality according to marital status with adjustment for potential confounders. RESULTS A total of 106 and 40 deaths from suicide were recorded during 344,813 and 365,524 person-years of follow-up among 20,671 men and 21,076 women, respectively. We found that marital status was significantly associated with the risk of completing suicide only in men. Among men, after multivariate adjustment, HRs in reference to married were as follows: widowed or divorced, 2.84 (95% CI: 1.37-5.90); unmarried, 1.56 (95% CI: 0.67-3.64). A significantly increased risk of suicidal death was observed among widowed or divorced men, whereas no such trend was evident for women. CONCLUSIONS Our results suggest that men who are widowed or divorced, or unmarried, are at increased risk of suicide, whereas no such risk is evident for women.

Cigarette smoking and lung cancer risk according to histologic type in Japanese men and women

Although cigarette smoking is a well‐known risk factor for lung cancer, histology‐specific risk has not been fully clarified in Japan. This case‐control study evaluated the associations between smoking and lung cancer risk according to sex and histologic type. From among patients aged 30 years and over admitted to a single hospital in Japan between 1997 and 2009, 1670 lung cancer cases and 5855 controls were selected. History of smoking, quantity and duration of smoking, and passive smoking from spouses were assessed using a self‐administered questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) for each exposure were estimated by unconditional logistic regression. Ever‐smoking was significantly associated with a higher risk of squamous cell and small cell carcinoma. The OR for these two histologic types combined was larger in women (OR = 24.98, 95% CI: 13.50–46.23) than in men (OR = 9.43, 95% CI: 5.73–15.51). Analysis of the quantity and duration of smoking showed that the OR for each exposure level tended to be larger in women than in men. For adenocarcinoma, clear positive associations with quantity and duration‐related factors were observed among men, and a significant positive association with passive smoking from spouses was found among non‐smoking women (OR = 1.44, 95% CI: 1.06–1.95). These results suggest sex‐ and histologic type‐ differences in the association of smoking with lung cancer risk. Although smoking control should be continued to prevent lung cancers, further studies are required to better clarify differences in smoking‐related lung cancer risk between the sexes and histologic types.

Personality and suicide risk: the impact of economic crisis in Japan.

Background The interactive effect of personal factors and social factors upon suicide risk is unclear. We conducted prospective cohort study to investigate whether the impact of the economic crisis in 1997–1998 upon suicide risk differed according to Neuroticism and Psychoticism personality traits. Methods The Miyagi Cohort Study in Japan with a follow-up for 19 years from 1990 to 2008 has 29 432 subjects aged 40–64 years at baseline who completed a questionnaire about various health habits and the Japanese version of the Eysenck Personality Questionnaire – Revised Short Form in 1990. Results The suicide mortality rate increased from 4.6 per 100 000 person-years before 1998 to 27.8 after 1998. Although both Neuroticism and Psychoticism were significantly associated with an increased risk of mortality during the whole period from 1990 to 2008, the impact of the economic crisis upon suicide risk differed between the Neuroticism and Psychoticism personality traits. Compared with the lowest category, the hazard ratios (HRs) for the highest Neuroticism increased from 0.66 before 1998 to 2.45 after 1998. On the other hand, the HRs for the highest Psychoticism decreased from 7.85 before 1998 to 2.05 after 1998. Conclusions The impact of the 1997–1998 economic crisis upon suicide risk differed according to personality. Suicide risk increased among these with higher Neuroticism after the economic crisis, but this was not the case for other personality subscales.

Sense of life worth living (ikigai) and incident functional disability in elderly Japanese: The Tsurugaya Project

OBJECTIVE To test the hypothesis that elderly persons who feel ikigai (a sense of life worth living) have a lower risk of incident functional disability than those who do not. Recent studies have suggested that ikigai impacts on mortality. However, its impact upon disability is unknown. The aim of the present study was to investigate the association between ikigai and incident functional disability among elderly persons. METHODS We conducted a prospective cohort study of 830 Japanese elderly persons aged ≥70 years as a comprehensive geriatric assessment in 2003. Information on ikigai was collected by self-reported questionnaire. Data on functional disability were retrieved from the public Long-term Care Insurance database in which participants were followed up for 11 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incidence of functional disability were calculated for three groups delineated according to the presence of ikigai (“no”, “uncertain” or “yes”) using the Cox proportional hazards regression model. RESULTS The 11-year incidence of functional disability was 53.3% (442 cases). As compared with the “no” group, the multiple-adjusted HR (95% CI) of incident functional disability was 0.61 (0.36–1.02) for the “uncertain” group and 0.50 (0.30–0.84) for the “yes” group. CONCLUSION A stronger degree of ikigai is significantly associated with a lower risk of incident functional disability.

Psychological distress and the incident risk of functional disability in elderly survivors after the Great East Japan Earthquake

BACKGROUND We conducted a prospective cohort study to investigate whether psychological distress would have increased the incident risk of functional disability after the 2011 Great East Japan Earthquake. METHODS First phase data pertaining to psychological distress and other lifestyle factors were collected from 1037 subjects aged ≥ 65 years, from June to December 2011, in four affected areas of Miyagi prefecture in Japan. Psychological distress was measured by the Kessler 6-item psychological distress scale (K6), and classified into three categories (K6 score ≤ 9, 10-12, ≥ 13). Outcome data on functional disability were collected from the public Long-term Care Insurance database. Participants were followed up for about 2.6 years. The Cox model was used to calculate the multivariate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS During the follow-up period, 118 participants were certified as incident disability (43.8 disability events per 1000 person-years). Compared with the lowest category (K6 score ≤ 9), participants in the highest category (K6 score ≥ 13) had a significantly higher risk of functional disability (HR = 2.65, 95% CI = 1.35-5.18, p = 0.002). In order to consider reverse causality, we conducted analysis excluding all incidents and deaths that occurred within the first year of follow-up, but our findings remained unchanged. LIMITATIONS We did not consider all potential confounders and use of appropriate medication. CONCLUSIONS The present study has demonstrated that psychological distress was associated with an increased risk of functional disability among elderly survivors of a natural disaster.

Body mass index and the risk of incident functional disability in elderly Japanese: The OHSAKI Cohort 2006 Study.

Abstract The relationship between the body mass index (BMI) and the incidence of cause-specific disability remains unclear. We conducted a prospective cohort study of 12,376 Japanese individuals aged ≥65 years who were followed up for 5.7 years. Information on BMI and other lifestyle factors was collected via a questionnaire in 2006. Functional disability data were retrieved from the public Long-term Care Insurance database. BMI was divided into 6 groups (<21, 21–<23, 23–<25, 25–<27[reference], 27–<29 and ≥29). Hazard ratios and 95% confidence intervals for cause-specific disability were estimated using Cox proportional hazards regression models. A U-shaped relationship between BMI and functional disability was observed, with a nadir at 26. The nadir BMI values with the lowest disability risk were 28 for dementia, 25 for stroke, and 23 for joint disease. A low BMI (<23) was a risk factor for disability due to dementia, the HR values (95% CI) being 2.48 (1.70–3.63) for BMI <21 and 2.25 (1.54–3.27) for BMI 21 to <23; a high BMI (≥29) was a risk factor for disability due to joint disease, the HR value (95% CI) being 2.17 (1.40–3.35). There was no significant relationship between BMI and disability due to stroke. The BMI nadirs for cause-specific disability differed: a low BMI (<23) was a risk factor for disability due to dementia, and a high BMI (≥29) was a risk factor for disability due to joint disease. Because BMI values of 23 to <29 did not pose a significantly higher risk for each cause of disability, this range should be regarded as the optimal one for the elderly population.

Nutritional characteristics of the Japanese diet: A cross-sectional study of the correlation between Japanese Diet Index and nutrient intake among community-based elderly Japanese

OBJECTIVES To our knowledge, the overall nutritional quality of the Japanese diet has not been assessed previously. The aim of this study was to investigate the relationship between adhering to a Japanese diet and nutrient intake. METHODS We conducted a cross-sectional study of 1129 Japanese persons ≥70 y of age. Dietary habits were assessed using a food frequency questionnaire. The primary outcome was nutrient intake (12 components of NRF9.3 index). The overall nutrient adequacy (ONA) score was applied for assessing the potential of nutrient density. Correlation analysis was performed to compare the Japanese Diet Index (JDI) and nutrient intake, and multiple regression analysis was used to simulate the modified JDI (MJDI). RESULTS The JDI was positively correlated with all nine beneficial nutrients, and negatively correlated with two nutrients (saturated fat and sugar). The JDI was significantly correlated with the ONA score (Spearmans coefficient = 0.248). The MJDI, which was defined by the coefficients for seven food items, was significantly correlated with the ONA score (Spearmans coefficient = 0.515). However, the JDI and MJDI were correlated with higher sodium intake. CONCLUSIONS The present findings suggest that adhering to a Japanese diet defined by the JDI score is associated with better nutrient intake. However, this dietary pattern also appears to be associated with high sodium intake.

Psychological distress and completed suicide in Japan: A comparison of the impact of moderate and severe psychological distress

It has already been established that severe psychological distress is a major risk factor for completed suicide. However, the impact (population attributable fraction; PAF) of moderate psychological distress on completed suicide has not been clarified. The present study investigated the association between various severities of psychological distress and completed suicide. We analyzed follow-up data covering a 7.3-year period (2006-2014) for 43,473 adults (aged ≥ 40 years) participating in a community-based, prospective cohort study. Psychological distress was measured using the K6 psychological distress scale at the baseline. Participants were classified into three groups according to their K6 score (low: 0-4; moderate: 5-12; severe: 13-24). Completed suicide was determined from a Japanese national database. The Cox model was used to estimate hazard ratios (HRs) for completed suicide. The PAFs of moderate and severe psychological distress for completed suicide were also estimated. The multivariate-adjusted HRs (95% confidence interval) for completed suicide were 2.37 (1.49-3.78) among participants with moderate psychological distress, and 4.16 (2.13-8.15) among those with severe psychological distress, relative to those with low psychological distress (P for trend < 0.001). The PAF of the moderate group for completed suicide was 26.8%, whereas that of the severe group was 10.9%. Not only severe but also moderate psychological distress was significantly associated with an increased risk of completed suicide. The PAF of moderate psychological distress for completed suicide was larger than that of severe psychological distress. Public health actions for suicide prevention should focus on moderate as well as severe psychological distress.

Association between social participation and incident risk of functional disability in elderly Japanese: The Ohsaki Cohort 2006

BACKGROUND Although several longitudinal studies have examined the relationship between social participation and incident functional disability, the related mechanisms have remained unclear. The aim of this study was to examine the mechanisms linking social participation to incident functional disability. METHODS We analyzed follow-up data for 11,992 older adults (≥65 years) participating in a community-based, prospective cohort study covering a 9-year period. At the baseline, the subjects were asked about three types of participation in community activities (volunteering, hobbies, and neighborhood associations) and the frequency of their participation. Data on incident functional disability were retrieved from the public Long-term Care Insurance database. The Cox model was used to estimate the multivariate-adjusted hazard ratios of incident functional disability. We then conducted mediation analysis to assess the magnitude of the mediating effect. RESULTS Among 84,760 person-years of follow-up, there were 3,984 cases of incident functional disability. The hazard ratio was 0.79 (95% CI: 0.73-0.86) for participating in one type of activity, 0.82 (95% CI: 0.74-0.90) for two types of activity and 0.70 (95% CI: 0.64-0.77) for three types of activity in comparison with no participation in any activity. Among the estimated mediating effects, cognitive activity accounted for 9.3%, time spent walking for 8.3%, psychological state for 4.6%, and social support for 2.8% of the reduced risk of incident functional disability. CONCLUSION The results of this population-based cohort study indicate that cognitive activity and time spent walking are important mechanisms linking social participation to incident functional disability.

Weight change since age 20 and incident risk of obesity-related cancer in Japan: A pooled analysis of the Miyagi Cohort Study and the Ohsaki Cohort Study

It is unclear whether weight change during adulthood affects the risk of obesity‐related cancers such as those of the esophagus, colorectum, pancreas, breast, endometrium, and kidney among Japanese, where obesity is less frequent and less severe. We examined the association between weight change during adulthood and the risk of obesity‐related cancer among Japanese by conducting a pooled analysis of two prospective studies of residents in Miyagi Prefecture, Japan. A total of 78,743 persons (40,422 women and 38,321 men) aged 40–79 years participated in the Miyagi Cohort Study in 1990 and in the Ohsaki Cohort Study in 1994. Weight change since age 20 was divided into four categories (weight loss; stable weight; moderate weight gain; high weight gain). Cox proportional hazards regression analysis was used to estimate the multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) for obesity‐related cancer incidence. During 1,057,899 person‐years of follow up, 4,467 cases of obesity‐related cancer (women; 1,916 cases, men; 2,551cases) were identified. In women, compared to the stable weight, weight gain was associated with an increased risk of obesity‐related cancer (moderate weight gain; HRs = 1.10, 95%CIs: 0.97–1.26, high weight gain; HRs = 1.29, 95%CIs: 1.14–1.47). The results indicate that weight gain since age 20 was associated with a significantly increased risk of obesity‐related cancer among Japanese women. By contrast, in men, our study found that weight change is not associated with the incidence of obesity‐related cancer.