Journal of Epidemiology Vol. 27(2017) No. 8

Japan's population is aging more rapidly than that of any other country. Frailty has recently been recognized as an important priority. Understanding the basic epidemiology of frailty in Japan, which is an example of a rapidly aging society, will be beneficial for Japan as well as other countries expecting an aging population. A systematic literature search of 11 electronic databases was conducted in March 2016 using a comprehensive set of Medical Subject Heading and text terms for any studies published in 2000 or later that report the prevalence of frailty among Japanese community-dwelling older people aged 65 years or older. A total of 1529 studies were identified in the systematic search, of which five studies were included in this review. The pooled prevalence of frailty, prefrailty, and robustness was 7.4% (95% confidence interval [CI], 6.1%–9.0%), 48.1% (95% CI, 41.6%–54.8%), and 44.4% (95% CI, 37.2%–51.7%), respectively. A significant degree of heterogeneity was observed. There was no evidence of publication bias. Age-stratified meta-analyses of four studies showed the pooled prevalence of frailty was 1.9%, 3.8%, 10.0%, 20.4%, and 35.1% for those aged 65–69, 70–74, 75–79, 80–84, and ≥85 years, respectively. Pooled prevalence of frailty was 8.1% for women and 7.6% for men. This review showed an overall pooled prevalence of frailty among Japanese community-dwelling older people of 7.4%. The age-stratified analysis suggested that Japanese older people are less frail before their late 70's but frailer in later life than older people in other countries. These findings provide important basic information for all parties involved in Japanese frailty research.

Background: The aim of this study was to examine the attribution of each cardiovascular risk factor in combination with abdominal obesity (AO) on Japanese health expenditures.

Methods: The health insurance claims of 43,469 National Health Insurance beneficiaries aged 40–75 years in Ibaraki, Japan, from the second cohort of the Ibaraki Prefectural Health Study were followed-up from 2009 through 2013. Multivariable health expenditure ratios (HERs) of diabetes mellitus (DM), high low-density lipoprotein cholesterol (LDL-C), low high-density lipoprotein cholesterol (HDL-C), and hypertension with and without AO were calculated with reference to no risk factors using a Tweedie regression model.

Results: Without AO, HERs were 1.58 for DM, 1.06 for high LDL-C, 1.27 for low HDL-C, and 1.31 for hypertension (all P < 0.05). With AO, HERs were 1.15 for AO, 1.42 for DM, 1.03 for high LDL-C, 1.11 for low HDL-C, and 1.26 for hypertension (all P < 0.05, except high LDL-C). Without AO, population attributable fractions (PAFs) were 2.8% for DM, 0.8% for high LDL-C, 0.7% for low HDL-C, and 6.5% for hypertension. With AO, PAFs were 1.0% for AO, 2.3% for DM, 0.4% for low HDL-C, and 5.0% for hypertension.

Conclusions: Of the obesity-related cardiovascular risk factors, hypertension, independent of AO, appears to impose the greatest burden on Japanese health expenditures.

Background: The relative and absolute risks of stroke and heart failure attributable to atrial fibrillation (AF) have not been sufficiently examined.

Methods: A prospective study of 23,731 community-dwelling Japanese individuals was conducted. Participants were divided into two groups based on the presence or absence of prevalent AF (n = 338 and n = 23,393, respectively). Excess events (EE) due to AF and relative risks (RRs) determined using the non-AF group as the reference for incident stroke and heart failure were estimated using Poisson regression stratified by age groups (middle-aged: 40–69 years old; elderly: 70 years of age or older) after adjustment for sex and age.

Results: There were 611 cases of stroke and 98 cases of heart failure during the observation period (131,088 person-years). AF contributed to a higher risk of stroke both in middle-aged individuals (EE 10.4 per 1000 person-years; RR 4.88; 95% confidence interval [CI], 2.88–8.29) and elderly individuals (EE 18.3 per 1000 person-years; RR 3.05; 95% CI, 2.05–4.54). AF also contributed to a higher risk of heart failure in middle-aged individuals (EE 3.7 per 1000 person-years; RR 8.18; 95% CI, 2.41–27.8) and elderly individuals (EE 15.4 per 1000 person-years; RR 7.82; 95% CI, 4.11–14.9). Results obtained from multivariate-adjusted analysis were similar (stroke: EE 8.9 per 1000 person-years; RR 4.40; 95% CI, 2.57–7.55 in middle-aged and EE 17.4 per 1000 person-years; RR 2.97; 95% CI, 1.99–4.43 in elderly individuals; heart failure: EE 3.1 per 1000 person-years; RR 7.22; 95% CI, 2.06–25.3 in middle-aged and EE 14.1 per 1000 person-years; RR 7.41; 95% CI, 3.86–14.2 in elderly individuals).

Conclusions: AF increased the risk of stroke by the same magnitude as that reported previously in Western countries. AF increased the RR of heart failure more than that in Western populations.

Background: Previous studies suggest that neighborhood social capital is associated with children's mental health. The purpose of this study was to examine the association between neighborhood collective efficacy and children's psychosocial development.

Methods: We used data on children and their parents (n = 918) who were part of the Japanese study of Stratification, Health, Income, and Neighborhood (JSHINE) from 2010 to 2013 (wave 1 and wave 2). Households were recruited from the Tokyo metropolitan area through clustered random sampling. Changes in children's psychosocial development (assessed using a child behavioral checklist) between waves 1 and 2 were regressed on parents' perceptions of changes in neighborhood collective efficacy (social cohesion and informal social control).

Results: Change in perception of neighborhood social cohesion was inversely associated with change in child total problems (β = −0.22; 95% confidence interval [CI]: −0.37 to −0.001; effect size d = −0.03). Change in perceptions of neighborhood informal social control was inversely associated with change in children's externalizing problems (β = −0.16; 95% CI: −0.30 to −0.03; d = −0.02).

Conclusions: The results of these fixed-effects models suggest that strengthening neighborhood collective efficacy is related to improvements in child psychosocial development.

Background: Little is known about the nationwide epidemiology of the annual rate, causative substance, and clinical course of overdose-related admission. We aimed to describe the epidemiology of overdose episodes from the period prior to hospitalization for drug poisoning until discharge to home.

Methods: We assessed all cases of admission due to overdose (21,663 episodes) in Japan from October 2012 through September 2013 using the National Database of Health Insurance Claims and Specific Health Checkups of Japan.

Results: The annual rate of overdose admission was 17.0 per 100,000 population. Women exhibited two peaks in admission rates at 19–34 years (40.9 per 100,000) and ≥75 years (27.8 per 100,000). Men exhibited one peak in the admission rate at ≥75 years (23.7 per 100,000). Within 90 days prior to overdose, ≥60% and ≥9% of patients aged 19–49 years received a prescription for benzodiazepines and barbiturates, respectively. In addition, 59% of patients aged ≥75 years received a prescription for benzodiazepines prior to overdose, 47% had a history of congestive heart failure, and 24% had a diagnosis of poisoning by cardiovascular drugs. The proportion of patients with recent psychiatric treatments decreased with age (65.1% in those aged 35–49 years and 13.9% in those aged ≥75 years).

Conclusions: The findings emphasize the need for overdose prevention programs that focus on psychiatric patients aged 19–49 years who are prescribed benzodiazepines or barbiturates and on non-psychiatric patients aged ≥75 years who are prescribed benzodiazepines or digitalis.

Introduction: The literature on stroke mortality and neighborhood effect is characterized by studies that are often Western society-oriented, with a lack of racial and cultural diversity. We estimated the effect of cross-level interaction between individual and regional socioeconomic status on the survival after onset of ischemic stroke.

Methods: We selected newly diagnosed ischemic stroke patients from 2002 to 2013 using stratified representative sampling data of 1,025,340 subjects. A total of 37,044 patients over the 10 years from 2004 to 2013 had newly diagnosed stroke. We calculated hazard ratios (HR) of 12- and 36-month mortality using the Cox proportional hazard model, with the reference group as stroke patients with high income in advantaged regions.

Results: For the middle income level, the patients in advantaged regions showed low HRs for overall mortality (12-month HR 1.27; 95% confidence interval [CI], 1.13–1.44; 36-month HR 1.25; 95% CI, 1.14–1.37) compared to the others in disadvantaged regions (12-month HR 1.36; 95% CI, 1.19–1.56; 36-month HR 1.30; 95% CI, 1.17–1.44). Interestingly, for the low income level, the patients in advantaged regions showed high HRs for overall mortality (12-month HR 1.27; 95% CI, 1.13–1.44; 36-month HR 1.33; 95% CI, 1.22–1.46) compared to the others in disadvantaged regions (12-month HR 1.25; 95% CI, 1.09–1.43; 36-month HR 1.30; 95% CI, 1.18–1.44).

Conclusion: Although we need to perform further investigations to determine the exact mechanisms, regional deprivation, as well as medical factors, might be associated with survival after onset of ischemic stroke in low-income patients.

Background: This study was designed to evaluate whether changes in lifestyle behaviors are correlated with the incidence of chronic kidney disease (CKD).

Methods: The subjects consisted of 316 men without a history of cardiovascular disease, stroke, or renal dysfunction or dialysis treatment. The following lifestyle behaviors were evaluated using a standardized self-administered questionnaire: habitual moderate exercise, daily physical activity, walking speed, eating speed, late-night dinner, bedtime snacking, skipping breakfast, and drinking and smoking habits. The subjects were divided into four categories according to the change in each lifestyle behavior from baseline to the end of follow-up (healthy–healthy, unhealthy–healthy, healthy–unhealthy and unhealthy–unhealthy).

Results: A multivariate analysis showed that, with respect to habitual moderate exercise and late-night dinner, maintaining an unhealthy lifestyle resulted in a significantly higher odds ratio (OR) for the incidence of CKD than maintaining a lifestyle (OR 8.94; 95% confidence interval [CI], 1.10–15.40 for habitual moderate exercise and OR 4.00; 95% CI, 1.38–11.57 for late-night dinner). In addition, with respect to bedtime snacking, the change from a healthy to an unhealthy lifestyle and maintaining an unhealthy lifestyle resulted in significantly higher OR for incidence of CKD than maintaining a healthy lifestyle (OR 4.44; 95% CI, 1.05–13.93 for healthy–unhealthy group and OR 11.02; 95% CI, 2.83–26.69 for unhealthy–unhealthy group).

Conclusions: The results of the present study suggest that the lack of habitual moderate exercise, late-night dinner, and bedtime snacking may increase the risk of CKD.