Shihoko Koyama

Development of an instrument for community-level health related social capital among Japanese older people: The JAGES Project

Background We developed and validated an instrument to measure community-level social capital based on data derived from older community dwellers in Japan. Methods We used cross-sectional data from the Japan Gerontological Evaluation Study, a nationwide survey involving 123,760 functionally independent older people nested within 702 communities (i.e., school districts). We conducted exploratory and confirmatory factor analyses on survey items to determine the items in a multi-dimensional scale to measure community social capital. Internal consistency was checked with Cronbachs alpha. Convergent construct validity was assessed via correlating the scale with health outcomes. Results From 53 candidate variables, 11 community-level variables were extracted: participation in volunteer groups, sports groups, hobby activities, study or cultural groups, and activities for teaching specific skills; trust, norms of reciprocity, and attachment to ones community; received emotional support; provided emotional support; and received instrumental support. Using factor analysis, these variables were determined to belong to three sub-scales: civic participation (eigenvalue = 3.317, α = 0.797), social cohesion (eigenvalue = 2.633, α = 0.853), and reciprocity (eigenvalue = 1.424, α = 0.732). Confirmatory factor analysis indicated the goodness of fit of this model. Multilevel Poisson regression analysis revealed that civic participation score was robustly associated with individual subjective health (Self-Rated Health: prevalence ratio [PR] 0.96; 95% confidence interval [CI], 0.94–0.98; Geriatric Depression Scale [GDS]: PR 0.95; 95% CI, 0.93–0.97). Reciprocity score was also associated with individual GDS (PR 0.98; 95% CI, 0.96–1.00). Social cohesion score was not consistently associated with individual health indicators. Conclusions Our scale for measuring social capital at the community level might be useful for future studies of older community dwellers.

Tooth Loss and Decline in Functional Capacity: A Prospective Cohort Study from the Japan Gerontological Evaluation Study

To describe associations between tooth loss and changes in higher‐level functional capacity.

Residential relocation and change in social capital: A natural experiment from the 2011 Great East Japan Earthquake and Tsunami

Group residential relocation of survivors helps to preserve social connections in the aftermath of a disaster. Social connections in the community (“social capital”) represent an important source of resilience in the aftermath of major disasters. However, little is known about how residential relocation due to housing destruction affects survivors’ social capital. We examined changes in social capital among survivors of the 2011 Great East Japan Earthquake and Tsunami. People who lost their homes were resettled to new locations by two primary means: (i) group relocation to public temporary trailer housing or (ii) individual relocation, in which victims moved into government-provided housing by lottery or arranged for their own accommodation (market rental housing or private purchase/new construction). The baseline for our natural experiment was established 7 months before the 11 March 2011 disaster, when we conducted a survey of older community-dwelling adults who lived 80-km west of the earthquake epicenter. Approximately 2.5 years after the disaster, the follow-up survey gathered information about personal experiences of disaster as well as health status and social capital. Among 3421 people in our study, 79 people moved via group relocation to public temporary trailer housing, whereas 96 people moved on their own. The individual fixed-effects model showed that group relocation was associated with improved informal socializing and social participation (β coefficient = 0.053, 95% confidence interval: 0.011 to 0.095). In contrast, individual relocation was associated with declining informal socializing and social participation (β coefficient = −0.039, 95% confidence interval: −0.074 to −0.003). Group relocation, as compared to individual relocation, appeared to preserve social participation and informal socializing in the community.

Community social capital and tooth loss in Japanese older people: a longitudinal cohort study

Objective To date, no study has prospectively examined the association between social capital (SC) in the community and oral health. The aim of this longitudinal cohort study was to examine the association between both community-level and individual-level SC and tooth loss in older Japanese people. Design Prospective cohort study Setting We utilised data from the Japan Gerontological Evaluation Study (JAGES) performed in 2010 and 2013 and conducted in 525 districts. Participants The target population was restricted to non-institutionalised people aged 65 years or older. Participants included 51 280 people who responded to two surveys and who had teeth at baseline. Primary outcome measure The primary outcome measure was loss of remaining teeth, measured by the downward change of any category of remaining teeth, between baseline and follow-up. Results The mean age of the participants was 72.5 years (SD=5.4). During the study period, 8.2% (n=4180) lost one or more of their remaining teeth. Among three community-level SC variables obtained from factor analysis, an indicator of civic participation significantly reduced the risk of tooth loss (OR 0.93; 95% CI 0.88 to 0.99). The individual-level SC variables ‘hobby activity participation’ and ‘sports group participation’ were also associated with a reduced risk of tooth loss (OR 0.88; 95% CI 0.81 to 0.95 and OR 0.90; 95% CI 0.82 to 0.99, respectively). Conclusions Living in a community with rich SC and individuals with good SC is associated with lower incidence of tooth loss among older Japanese people.

Impact of Loss of Removable Dentures on Oral Health after the Great East Japan Earthquake: A Retrospective Cohort Study

PURPOSE The Great East Japan Earthquake in March 2011 destroyed many communities, and as a result many older victims lost their removable dentures. No previous studies have documented the prevalence of denture loss after a natural disaster or examined its negative impact. Therefore, investigation of the consequences of such a disaster on oral health is of major importance from a public health viewpoint. MATERIALS AND METHODS Three to five months after the disaster, questionnaire surveys were conducted in two coastal towns, Ogatu and Oshika, located in the area of Ishinomaki city, Miyagi prefecture. Among the survey participants, 715 individuals had used one or more removable dentures before the disaster, and these comprised the population analyzed. The effect of denture loss on oral health-related quality life (OHRQoL) was examined by a modified Poisson regression approach with adjustment for sex, age, subjective household economic status, dental caries, tooth mobility, psychological distress (K6), access to a dental clinic, physical activity, and town of residence. RESULTS There were 123 (17.2%) participants who had lost their dentures. In comparison with participants who had not lost their dentures, those lacking dentures showed a significantly higher relative risk for eating difficulties (RR = 2.65, 95%CI = 1.90-3.69), speech problems (RR = 4.37, 95%CI = 2.46-7.76), embarrassment upon smiling, laughing, or showing their teeth (RR = 5.32, 95%CI = 2.34-12.1), emotional distress (RR = 2.38, 95%CI = 1.41-4.03), and problems related to social interaction (RR = 6.97, 95%CI = 1.75-27.7). CONCLUSIONS Denture loss appeared to impair eating and speaking ability, thus discouraging communication with others. Public health intervention after major natural disasters should include dental care.

Dental Status and Compression of Life Expectancy with Disability

This study examined whether the number of teeth contributes to the compression of morbidity, measured as a shortening of life expectancy with disability, an extension of healthy life expectancy, and overall life expectancy. A prospective cohort study was conducted. A self-reported baseline survey was given to 126,438 community-dwelling older people aged ≥65 y in Japan in 2010, and 85,161 (67.4%) responded. The onset of functional disability and all-cause mortality were followed up for 1,374 d (follow-up rate = 96.1%). A sex-stratified illness-death model was applied to estimate the adjusted hazard ratios (HRs) for 3 health transitions (healthy to dead, healthy to disabled, and disabled to dead). Absolute differences in life expectancy, healthy life expectancy, and life expectancy with disability according to the number of teeth were also estimated. Age, denture use, socioeconomic status, health status, and health behavior were adjusted. Compared with the edentulous participants, participants with ≥20 teeth had lower risks of transitioning from healthy to dead (adjusted HR, 0.58 [95% confidence interval (CI), 0.50–0.68] for men and 0.70 [95% CI, 0.57–0.85] for women) and from healthy to disabled (adjusted HR, 0.52 [95% CI, 0.44–0.61] for men and 0.58 [95% CI, 0.49–0.68] for women). They also transitioned from disabled to dead earlier (adjusted HR, 1.26 [95% CI, 0.99–1.60] for men and 2.42 [95% CI, 1.72–3.38] for women). Among the participants aged ≥85 y, those with ≥20 teeth had a longer life expectancy (men: +57 d; women: +15 d) and healthy life expectancy (men: +92 d; women: +70 d) and a shorter life expectancy with disability (men: –35 d; women: –55 d) compared with the edentulous participants. Similar associations were observed among the younger participants and those with 1 to 9 or 10 to 19 teeth. The presence of remaining teeth was associated with a significant compression of morbidity: older Japanese adults’ life expectancy with disability was compressed by 35 to 55 d within the follow-up of 1,374 d.

Risk of mortality during and after the 2011 Great East Japan Earthquake and Tsunami among older coastal residents

The Japan Gerontological Evaluation Study is a nationwide cohort study of individuals aged 65 years and older established in July 2010. Seven months later, one of the study field sites was directly in the line of the 2011 Great East Japan Earthquake and Tsunami. Despite the 1-hour warning interval between the earthquake and tsunami, many coastal residents lost their lives. We analyzed the risk of all-cause mortality on the day of the disaster as well as in the 38-month interval after the disaster. Among 860 participants, 33 (3.8%) died directly because of the tsunami and an additional 95 people died during the 38-month follow-up period. Individuals with depressive symptoms had elevated risk of mortality on the day of the disaster (odds ratio = 3.90 [95% CI: 1.13, 13.47]). More socially connected people also suffered increased risk of mortality, although these estimates were not statistically significant. In contrast, after the disaster, frequent social interactions reverted back to predicting improved survival (hazard ratio = 0.46 (95% CI: 0.26, 0.82)). Depressive symptoms and stronger social connectedness were associated with increased risk of mortality on the day of the disaster. After the disaster, social interactions were linked to improved survival.

Does Type of Residential Housing Matter for Depressive Symptoms in the Aftermath of a Disaster? Insights From the Great East Japan Earthquake and Tsunami

Abstract The 2011 Great East Japan Earthquake and Tsunami resulted in widespread property destruction and over 250,000 displaced residents. We sought to examine whether the type of housing arrangement available to the affected victims was associated with a differential incidence of depressive symptoms. In this prospective cohort study, which comprised participants aged ≥65 years from Iwanuma as a part of the Japan Gerontological Evaluation Study, we had information about the residents’ mental health both before the disaster in 2010 and 2.5 years afterward. The Geriatric Depression Scale was used. Type of accommodation after the disaster was divided into 5 categories: no move, prefabricated housing (temporary housing), existing private accommodations (temporary apartment), newly established housing, and other. Poisson regression analysis was adopted, with and without multiple imputation. Among the 2,242 participants, 16.2% reported depressive symptoms at follow-up. The adjusted rate ratio for depressive symptoms among persons moving into prefabricated housing, compared with those who did not, was 2.07 (95% confidence interval: 1.45, 2.94). Moving into existing private accommodations or other types of accommodations was not associated with depression. The relationship between living environment and long-term mental health should be considered for disaster recovery planning.

Generalized and particularized trust for health between urban and rural residents in Japan: A cohort study from the JAGES project

Previous studies on trust and health have not fully considered the nature of trust in relation to types of trust and socio-cultural background. The present study aimed to examine whether generalized trust (trust in general people; GT) and particularized trust (trust in particular people; PT) in urban and rural areas had different associations with health. This prospective cohort study on older adults used panel data obtained in 2010 and 2013. Surveys were conducted in 24 municipalities in Japan. Of 20,209 respondents, 13,657 participants were followed up. The independent variables were GT and PT in neighbors; the dependent variable was self-rated health (SRH) at follow-up. We examined the interaction term between population density and each trust variable. Age, sex, SRH at the baseline, and other potential confounders were adjusted. The median age was 72 years (females: 53.4%). Percentages of high GT and high PT were 21.0% and 72.4%, respectively. Prevalence of poor SRH at the follow-up was 15.5% and 28.5% in high and low GT, respectively, and 16.9% and 32.8% in high and low PT, respectively. After adjusting for covariates in logistic regression models, low GT and PT were significantly associated with higher odds ratios (ORs) for poor SRH compared to high trust (GT: OR = 1.43 [95% confidence interval (95%CI) = 1.17, 1.75] and PT: OR = 1.44 [95%CI = 1.15, 1.81]). Associations of low PT with poor SRH significantly strengthened when population density increased (interaction term of low PT: OR = 1.16 [95%CI = 1.04, 1.27]). On the other hand, associations of GT with SRH were not significantly interacted by population density. The mediation analysis showed that the direct effects of PT influenced SRH in urban areas only. In urban areas with high social uncertainty, trust in particular neighbors was more beneficial to health.

Does cigarette smoking increase traffic accident death during 20 years follow-up in Japan?: The Ibaraki Prefectural Health Study

Background Annually, more than 1.2 million deaths due to road traffic accidents occur worldwide. Although previous studies have examined the association between cigarette smoking and injury death, the mortality outcome often included non-traffic accident-related deaths. This study aimed to examine the association between cigarette smoking and traffic accident death. Methods We conducted a prospective cohort study using data from the Ibaraki Prefectural Health Study conducted from 1993 through 2013. The cohort included 97,078 adults (33,138 men and 63,940 women) living in Ibaraki Prefecture who were aged 40–79 years at an annual health checkup in 1993. We divided participants into four smoking status groups: non-smokers, ex-smokers, and current smokers who smoked <20 and ≥20 cigarettes per day. Hazard ratios (HRs) of traffic accident death were calculated using a Cox proportional hazards model. Results During 20 years of follow-up, the average person-years of follow-up were 16.8 and 18.2 in men and women, respectively. Among men, after adjusting for age and alcohol intake, HRs for traffic accident death among current smokers of <20 cigarettes/day and ≥20 cigarettes/day compared to non-smokers were 1.32 (95% confidence interval [CI], 0.79–2.20) and 1.54 (95% CI, 0.99–2.39), respectively. In contrast, among women, we found no association between smoking status and traffic accident deaths. Conclusion In this prospective cohort study, we found a positive association, though marginally significant, between smoking and traffic accident death among men in Japan. Among women, because of the smaller number of deaths among smokers, adequate estimation could not be obtained.