Background: Identifying which exposures cause disease and quantifying their impacts is essential in promoting and monitoring public health. When multiple exposures are involved, measuring individual contributions becomes challenging.

Methods: The authors propose a disease attribution method based on aggregate data or summary statistics of individual-level data, possibly from multiple data sources.

Results: Using the proposed method, the burden of disease is apportioned to the independent and interaction effects of each of its major risk factors and all the other factors as a whole. This scheme guarantees that 100% is the total share of the burden.

Conclusion: The calculation is simple and straightforward; therefore, it is recommended for use in studies on disease burden.

Background: This longitudinal study aimed to investigate how psychological distress levels changed from early to middle phases of the new coronavirus (COVID-19) pandemic depending on the living arrangements of individuals.

Methods: An internet-based, longitudinal survey of 2,400 Japanese people was conducted every 5–6 weeks between February 2020 and January 2021. The presence of severe psychological distress (SPD) was measured using the Kessler’s psychological distress scale. Living arrangements were classified into two groups (ie, living alone or living with others). Mixed-effects logistic regression analysis was performed to assess whether changes in SPD status were different depending on living arrangements.

Results: Of 2,400 respondents, 446 (18.5%) lived alone. Although the proportion of SPD in both individuals living alone and those living with others increased to the same extent in the early phase of the pandemic, the distress levels decreased after the early phase of the pandemic in the group living with others, compared with the group living alone, for which SPD remained high. The odds ratio (OR) of developing SPD in interaction term with survey phases tended to be higher among those who lived alone than those who lived with others in Phase 6 (OR 1.89; 95% confidence interval [CI], 0.99–3.64) and Phase 7 (OR 1.88; 95% CI, 0.97–3.63).

Conclusion: During the COVID-19 pandemic, those living alone are persistently at a higher risk of SPD compared to those living with others. Effective countermeasures targeting those living alone, such as enhancing online communication or providing psychological therapies, are essential.

Background: It has not been determined whether mentally active sedentary behavior (MASB) and passive sedentary behavior (PSB) differentially affect cognitive function, and whether these associations differ according to physical activity (PA) level. We examined the comparative impacts of MASB and PSB on dementia onset and aimed to understand whether the associations differed by PA level.

Methods: A 5-year longitudinal study involving all community-dwelling older adults in a rural area in Japan (n = 5,323). Dementia onset was examined using long-term care insurance data. PA was evaluated using the International Physical Activity Questionnaire and categorized as low (<2.5 MET-h/week), moderate (<16.0 MET-h/week), or high (≥16.0 MET-h/week). We also assessed PSB (TV-watching time; <1 h/day, <3 h/day, ≥3 h/day) and MASB (Book-reading time; <10 min/day, <30 min/day, ≥30 min/day). To examine the associations of MASB and PSB with dementia onset, we performed the Fine-Gray models accounting for competing risk of death.

Results: During the follow-up period, 606 (11.4%) participants developed dementia. MASB was independently associated with a lower risk of dementia; the magnitude of the impact was significant at higher PA levels. There was no association between PSB and developing dementia across all PA levels. Furthermore, dementia risk for individuals with high PA levels and moderate or high MASB levels was approximately 60% lower than those with low PA levels and low MASB.

Conclusions: Providing interventions to promote MASB, which reduces dementia risk, and PA, which increases MASB's effect on dementia incidence, can be beneficial in delaying or preventing dementia onset.

Background: The association between hobby engagement and risk of dementia reported from a short-term follow-up study for individuals aged ≥65 years may be liable to reverse causation. We examined the association between hobby engagement in age of 40-69 years and risk of dementia in a long-term follow-up study among Japanese including individuals in mid-life, when the majority of individuals have normal cognitive function.

Methods: A total of 22,377 individuals aged 40–69 years completed a self-administered questionnaire in 1993–1994. The participants answered whether they had hobbies according to the three following responses: having no hobbies, having a hobby, and having many hobbies. Follow-up for incident disabling dementia was conducted with long-term care insurance data from 2006 to 2016.

Results: During 11.0 years of median follow-up, 3,095 participants developed disabling dementia. Adjusting for the demographic, behavioral, and psychosocial factors, the multivariable hazard ratios (95% confidence intervals) of incident disabling dementia compared with “having no hobbies” were 0.82 (0.75–0.89) for “having a hobby” and 0.78 (0.67–0.91) for “having many hobbies”. The inverse association was similarly observed in both middle (40-64 years) and older ages (65-69 years). For disabling dementia subtypes, hobby engagement was inversely associated with the risk of dementia without a history of stroke (probably non-vascular type dementia), but not with that of post-stroke dementia (probably vascular type dementia).

Conclusions: Hobby engagement in both mid-life and late-life was associated with a lower risk of disabling dementia without a history of stroke.

Background: Desired longevity represents how strongly people esteem possible extensions of their own lifetime. The association between desired longevity and mortality risk has been reported in only one prospective study, which examined a small sample of older participants. We aimed to examine the hypothesis that desired longevity at middle-age predicted long-term survival.

Methods: In the prospective cohort study, residents aged 40–64 years were asked how long they would like to live and asked to choose one from three options: longer than, as long as, or shorter than the life expectancy. We used Cox proportional hazards model to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality according to the three groups for desired longevity, treating the “longer than” group as the reference. We conducted mediation analysis to investigate the mechanism for the association between desired longevity and mortality.

Results: 39,902 residents were recruited to the study. Risk of all-cause mortality was significantly higher in the “shorter than” group (HR 1.12; 95% CI, 1.04-1.21). The association was independent of sex, age, marital status, education, medical history and health status. Regarding cause of death, mortality risk of cancer (HR 1.14; 95% CI, 1.00-1.29) and suicide (HR 2.15; 95% CI, 1.37-3.38) were also higher in the “shorter than” group. The unhealthy lifestyle mediated this association with all-cause mortality by 30.4%.

Conclusions: Shorter desired longevity was significantly associated with an increased risk of all-cause mortality, and mortality from cancer and suicide. Lifestyle behaviors particularly mediated this association.

Background: No studies have examined the associations between adult height and ischemic stroke subtypes.

Methods: We conducted a population-based case-control study that included 2,451 thrombotic and 687 embolic stroke cases, as well as 1,623 intracerebral and 768 subarachnoid hemorrhage cases without history of stroke aged 40–79 years, and the same number of sex- and age-matched controls. Cases and controls were grouped according to the quintile cut-off values of height in controls, and the third quintile, which was approximately the average height group, was used as the reference group. Height divided by one standard deviation of height in controls was also examined as a continuous variable. The analyses were carried out separately for participants aged 40–59 years and 60–79 years.

Results: In both younger and older men, height was linearly inversely associated with total and thrombotic strokes, and the shortest quintile compared to the reference group was associated with increased risks of these strokes. Although height was linearly inversely associated with embolic stroke and intracerebral hemorrhage in younger men, the shortest quintile did not show increased risks of these strokes. Height did not seem to be associated with total stroke and any stroke subtypes in younger women. In contrast, the tallest quintile was significantly associated with increased risks of total stroke and intracerebral hemorrhage, and height tended to be positively associated with these strokes in older women.

Conclusion: We reported the associations between adult height and ischemic stroke subtypes for the first time, which differed according to sex and age group.

Background: Stress coping strategies are related to health outcomes. However, there is no clear evidence for sex differences between stress-coping strategies and mortality. We investigated the relationship between all-cause mortality and stress-coping strategies, focusing on sex differences among Japanese adults.

Methods: A total of 79,580 individuals aged 35–69 years participated in the Japan Multi-Institutional Collaborative Cohort Study between 2004 and 2014 and were followed up for mortality. The frequency of use of the five coping strategies was assessed using a questionnaire. Sex-specific, multivariable-adjusted hazard ratios (HRs) for using each coping strategy (“sometimes,” and “often/very often” use versus “very few” use) were computed for all-cause mortality. Furthermore, relationships were analyzed in specific follow-up periods when the proportion assumption was violated.

Results: During the follow-up (median: 8.5 years), 1,861 mortalities were recorded. In women, three coping strategies were related to lower total mortality. The HRs for “sometimes” were 0.81 (95% confidence interval [CI], 0.67–0.97) for emotional expression, 0.79 (95% CI, 0.66–0.95) for emotional support-seeking, and 0.80 (95% CI, 0.66–0.98) for disengagement. Men who “sometimes” used emotional expression and sometimes or often used problem-solving and positive reappraisal had a 15–41% lower HRs for all-cause mortality. However, those relationships were dependent on the follow-up period. There was evidence that sex modified the relationships between emotional support-seeking and all-cause mortality (P for interaction = 0.03).

Conclusion: In a large Japanese sample, selected coping strategies were associated with all-cause mortality. The relationship of emotional support-seeking was different between men and women.

Background: The EU LifeCycle Project was launched in 2017 to combine, harmonize, and analyze data from more than 250,000 participants across Europe and Australia, involving cohorts participating in the EU-funded LifeCycle Project. The purpose of this cohort description is to provide a detailed overview of the major measures within mental health domains that are available in 17 European and Australian cohorts participating in the LifeCycle Project.

Methods: Data on cognitive, behavioral, and psychological development has been collected on participants from birth until adulthood through questionnaire and medical data. We developed an inventory of the available data by mapping individual instruments, domain types, and age groups, providing the basis for statistical harmonization across mental health measures.

Results: The mental health data in LifeCycle contain longitudinal and cross-sectional data from birth throughout the life course, covering domains across a wide range of behavioral and psychopathology indicators and outcomes, including executive function, depression, ADHD, and cognition. These data span a unique combination of qualitative data collected through behavioral/cognitive/mental health questionnaires and examination, as well as data from biological samples and indices in the form of imaging (MRI, fetal ultrasound) and DNA methylation data. Harmonized variables on a subset of mental health domains have been developed, providing statistical equivalence of measures required for longitudinal meta-analyses across instruments and cohorts.

Conclusion: Mental health data harmonized through the LifeCycle project can be used to study life-course trajectories and exposure-outcome models that examine early life risk factors for mental illness and develop predictive markers for later-life disease.

Background Little is known about the association between a plant-based diet and the risk of Gallstone disease (GD), especially in developing counties. We tested the hypothesis that the shifting dietary pattern would be related to the risk of GD, and the Mediterranean diet (MED) adjusted for China was still beneficial for the lower risk of GD.

Methods Data were extracted from the baseline survey of the China Multi-Ethnic Cohort study. An alternative Mediterranean diet (aMED) score was accessed based on the food frequency questionnaire and three posteriori dietary patterns (the modern dietary pattern, the coarse grain dietary pattern, and the rice dietary pattern) were identified by factor analysis. Multivariable logistic regression models were developed to evaluate the association between dietary patterns and GD risks.

Results A total of 89 544 participants were included. The prevalence of GD was 7.5%. Comparing the highest with lowest quintiles, aMED was associated with an increased risk of GD (OR:1.13; 95% CI:1.04-1.24; p trend = 0.003), whereas the rice dietary pattern was inversely related to GD risk (OR: 0.79; 95% CI:0.71-0.87; p trend < 0.001). After the stratified analysis, the rice dietary pattern has a stronger inverse association in the subgroup of female, the older, the urban, the fat, and diabetes—factors associated with higher rates of GD in previous studies.

Conclusion Higher adherence to the rice dietary pattern was associated with a lower risk of GD. For the high-risk populations, making some shift to a traditional agricultural diet might help with the primary prevention of GD.

Background: White rice is a staple food for Japanese, a population at high risk for colorectal cancer (CRC). We investigated the association between white rice intake and CRC among Japanese Americans in the Multiethnic Cohort (MEC) study.

Methods: The MEC study is a prospective study established in Hawaii and California in 1993–1996. Usual dietary intake was assessed using a validated quantitative food frequency questionnaire at baseline. Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for quartiles of intake and to perform trend tests across sex-specific quartiles with adjustment for relevant confounders.

Results: We identified 1,553 invasive CRC cases among 49,136 Japanese Americans (23,595 men and 25,541 women) during a mean follow-up of 19 years. White rice consumption was not associated with overall CRC incidence in men (P_trend = 0.11) or women (P_trend = 0.56). After excluding participants with a history of diabetes, the inverse associations were significant for CRC (P_trend = 0.03, HR for quartile 4 [Q4] vs quartile 1 [Q1], 0.81; 95% CI, 0.64–1.03) and tumors of the distal colon (P_trend = 0.006, HR for Q4 vs Q1, 0.66; 95% CI, 0.44–0.99) among men but not women.

Conclusion: White rice consumption was not associated with an increased risk of overall CRC among Japanese Americans. An inverse association was observed with risk of CRC and distal colon cancer in men without a history of diabetes.

Background: Developmental dysplasia of the hip (DDH) is a cluster of hip development disorders that affects infants. The incidence of DDH-related dislocation (DDH-dislocation) is reportedly 0.1–0.3%; however, the nationwide incidence of DDH-dislocation in Japan has not been previously reported. The primary aim of this study was to report the nationwide incidence of DDH-dislocation in Japan using the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB), and to examine its regional variation across Japan.

Methods: This was a retrospective birth cohort study using the NDB. Data on patients born between 2011 and 2013 and assigned DDH-dislocation-related disease codes during 2011–2018 were extracted. Among these, patients who underwent treatment for DDH-dislocation between 2011 and 2018 were defined as patients with DDH-dislocation.

Results: Across the 2011, 2012, and 2013 birth cohorts, 2,367 patients were diagnosed with DDH-dislocation, yielding the nationwide incidence of 0.076%. Region-specific incidence rates were almost similar across Japan. Secondary analyses revealed that 273 (11.5%) patients were diagnosed at the age of ≥1 year. The effect of birth during the cold months on the incidence of DDH-dislocation was significant (relative risk [RR] = 1.89, 95% confidence interval [CI]: 1.75–2.06). The risk of DDH-dislocation among girls was approximately seven times higher than that among boys.

Conclusion: This is the first study to report the nationwide incidence of DDH-dislocation in Japan, which was estimated at 0.076%. The regional variation was trivial and unlikely to be clinically significant. Thus, the incidence rates were approximately equal across all regions in Japan.

Background: Postpartum depression (PPD) has been associated with adverse health outcomes, including maternal suicide. Mode of delivery has been suggested to be a risk factor for PPD, but no large cohort study has examined the association between mode of delivery and PPD. We aimed to examine the association between mode of delivery and risks of PPD at 1 and 6 months after childbirth.

Methods: In a nationwide study of 89,954 mothers with a live singleton birth, we examined the association between mode of delivery and risks of PPD. PPD was evaluated using the Edinburgh Postnatal Depression Scale (≥13) at 1 and 6 months after childbirth. Odds ratios (ORs) with 95% confidence intervals (CIs) of PPD were calculated using multivariable logistic regression analyses after adjustment of antenatal physical, socioeconomic, and mental factors.

Results: Among 89,954 women, 3.7% and 2.8% had PPD at 1 and 6 months after childbirth, respectively. Compared with unassisted vaginal delivery, cesarean section (CS) was marginally associated with PPD at 1 month but not at 6 months; adjusted ORs were 1.10 (95% CI, 1.00–1.21) and 1.01 (95% CI, 0.90–1.13), respectively. The association with PPD at 1 month was evident in women with antenatal psychological distress (adjusted OR 1.15; 95% CI, 1.03–1.28). The observed associations were attenuated after adjusting for infant feeding method.

Conclusion: Women who had antenatal psychological distress and underwent CS delivery may be regarded as a target for monitoring PPD.

Background: Metabolic syndrome (MetS) has been associated with various chronic diseases that may lead to long-term sickness absence (LTSA), but there is lacking information on the direct association between MetS and LTSA. The present study aimed to investigate the all-cause and cause-specific associations between MetS and the risk of medically certified LTSA among Japanese workers.

Methods: We recruited 67,403 workers (57,276 men and 10,127 women), aged 20–59 years from 13 companies in Japan during their health check-ups in 2011 (11 companies) and 2014 (2 companies), and we followed them for LTSA events (≥30 consecutive days) until March 31, 2020. MetS was defined according to the Joint Interim Statement. A Cox proportional hazards regression model was used to estimate hazard ratios (HRs) and its 95% confidence intervals (CIs) for LTSA associated with MetS and its components.

Results: During 408,324 person-years of follow-up, 2,915 workers experienced LTSA. The adjusted HR for all-cause LTSA was 1.54 (95% CI, 1.41–1.68) among those with MetS compared to those without MetS. In cause-specific analysis, HRs associated with MetS significantly increased for LTSA due to overall physical disorders (1.76); cardiovascular diseases (3.16); diseases of the musculoskeletal system and connective tissue (2.01); cancers (1.24); obesity-related cancers (1.35); mental, behavioral, and neurodevelopmental disorders (1.28); reaction to severe stress and adjustment disorders (1.46); and external causes (1.46). The number of MetS components were also significantly associated with increased LTSA risk.

Conclusion: MetS was associated with an increase in the risk of LTSA due to various diseases among Japanese workers.

Background: The number of people with cognitive impairment, including dementia, in the world is steadily increasing. Although the consumption of isoflavones and soy is associated with a reduced risk of cardiovascular disease, it might also be associated with cognitive impairment. The low number of studies investigating the association between soy/isoflavone intake and cognitive function warrant additional research.

Methods: The Japan Public Health Center-based prospective (JPHC) Study is a large population-based cohort. Midlife dietary intake of soy and the isoflavone genistein was assessed on two occasions: in the years 1995 and 2000. In 2014–2015, 1,299 participants from Nagano prefecture completed a mental health screening. Of these, a total of 1,036 participants were included in analyses. Logistic regression was used to determine Odds Ratios (OR) and 95% Confidence Intervals (CI) for the association between midlife energy-adjusted genistein and soy food intake and cognitive impairment.

Results: There were 392 cases of cognitive impairment (346 cases of MCI and 46 cases of dementia). Compared to the lowest dietary quartile of energy-adjusted genistein intake, the highest quartile was significantly associated with cognitive impairment (OR = 1.51; 95% CI, 1.02–2.24; P for trend = 0.03) in the final multivariable analysis.

Conclusion: High midlife intake of the isoflavone genistein is associated with late-life cognitive impairment.

Background: In Japan, ten percent of single-parent households are led by fathers. Taking care of children as a single father is very stressful and could put a strain on their health. It is very important to prevent and identify psychological distress among fathers for both their own health and to avoid negative impacts on children. This study aims to determine the prevalence of and factors associated with psychological distress among single fathers and understand how it is different from partnered fathers.

Methods: We used data from the Comprehensive Survey of Living Conditions 2016. Psychological distress, assessed using the K6 scale, was analyzed among 868 single and 43,880 partnered fathers. Logistic regression analysis was performed to assess the risk factors for psychological distress, such as employment type, sleep hours, and smoking and drinking habits.

Results: Single fathers had a higher proportion (8.5%) of psychological distress compared to partnered fathers (5.0%). A larger percentage of single fathers had a lower educational level and were more likely to be non-regular workers, self-employed, or unemployed than partnered fathers. Among single fathers, the crude and adjusted odds ratio for employment type and sleep hours were significantly associated with psychological distress.

Conclusion: As single parents who are self-employed or directors are likely to have significantly reduced psychological distress than those with regular jobs, measures are needed to improve the work-family balance for non-self-employed fathers. There is a need to provide greater financial assistance and other social welfare support to single parents to ensure their and their children’s good health.

Background: Limited data on electronic cigarette prevalence, patterns, and settings of use are available from several European countries.

Methods: Within the TackSHS project, a face-to-face survey was conducted in 2017–2018 in 12 European countries (Bulgaria, England, France, Germany, Greece, Ireland, Italy, Latvia, Poland, Portugal, Romania and Spain). Overall, 11,876 participants, representative of the population aged ≽15 years in each country, provided information on electronic cigarette.

Results: 2.4% (95% confidence interval [CI], 2.2–2.7%) of the subjects (2.5% among men and 2.4% among women; 0.4% among never, 4.4% among current- and 6.5% among ex-smokers) reported current use of electronic cigarette, ranging from 0.6% in Spain to 7.2% in England. Of the 272 electronic cigarette users, 52.6% were dual users (ie, users of both electronic and conventional cigarettes) and 58.8% used liquids with nicotine. In all, 65.1% reported using electronic cigarette in at least one indoor setting where smoking is forbidden; in particular, at workplaces (34.9%) and bars and restaurants (41.5%). Multivariable logistic regression analysis showed that electronic cigarette use was lower among older individuals (P for trend <0.001) and higher among individuals with high level of education (P for trend = 0.040). Participants from countries with higher tobacco cigarette prices more frequently reported electronic cigarette use (odds ratio 3.62; 95% CI, 1.80–7.30).

Conclusion: Considering the whole adult population of these 12 European countries, more than 8.3 million people use electronic cigarettes. The majority of users also smoked conventional cigarettes, used electronic cigarettes with nicotine, and consumed electronic cigarettes in smoke-free indoor areas.

Background: Pathological gaming (PG) has emerged as one of the major public health concerns worldwide. We aimed to assess PG and its associated factors among elementary school children in Japan.

Methods: We conducted a school-based observational study in Toyama, Japan in 2018. In total, 13,413 children in the 4th–6th grades (mean age, 10.5 years) participated in the study. We distributed questionnaires and inquired about their lifestyle, irritability, and school and family environments. Referring to criteria of gaming disorder in the International Statistical Classification of Disease (ICD-11), we asked about three core symptoms: impaired control over gaming, increasing priority given to gaming over other activities, and continuation of gaming despite the negative consequences. Children who had all three criteria in the questionnaire were defined as PG.

Results: The response rate was 97.6%, and 11,826 children were included in our analyses (88.2%). The prevalence of PG was 5.6% (7.8% in boys, 3.2% in girls). Besides sex, PG was significantly associated with lifestyles, including skipping breakfast (odds ratio [OR] 1.33; 95% confidence interval [CI], 1.05–1.68), physical inactivity (OR 2.23; 95% CI, 1.63–3.05 for rare), late bed time (OR 2.52; 95% CI, 1.96–3.25 for ≥11 p.m.), frequent irritability (OR 1.89; 95% CI, 1.47–2.43), frequent feeling of school avoidance (OR 1.92; 95% CI, 1.49–2.46), fewer close friends (OR 1.30; 95% CI, 1.08–1.56 for some), low academic performance (OR 1.53; 95% CI, 1.13–2.08), no child–parent interaction (OR 1.34; 95% CI, 1.02–1.75), and no rules at home (OR 1.21; 95% CI, 1.02–1.43).

Conclusion: Unhealthy lifestyles, irritability, and low functioning in school and family environments were associated with PG. Besides having a healthy lifestyle, parental involvement appears to be an indispensable countermeasure for PG in children.

Background: This 3.6-year prospective study examined combined impacts of physical activity, dietary variety, and social interaction on incident disability and estimated population-attributable fraction for disability reduction in older adults.

Methods: Participants were 7,822 initially non-disabled residents (3,966 men and 3,856 women) aged 65–84 years of Ota City, Tokyo, Japan. Sufficiency of moderate-to-vigorous-intensity physical activity (MVPA) ≥150 min/week, dietary variety score (DVS) ≥3 (median), and social interaction (face-to-face and/or non-face-to-face) ≥1 time/week was assessed using self-administered questionnaires. Disability incidence was prospectively identified using the long-term care insurance system’s nationally unified database.

Results: During a follow-up of 3.6 years, 1,046 (13.4%) individuals had disabilities. Independent multivariate-hazard ratios (HRs) and 95% confidence intervals (CIs) of MVPA, DVS, and social interaction sufficiency for incident disability were 0.68 (95% CI, 0.59–0.78), 0.87 (95% CI, 0.77–0.99), and 0.90 (95% CI, 0.79–1.03), respectively. Incident disability HRs gradually reduced with increased frequency of satisfying these behaviors (any one: HR 0.82; 95% CI, 0.65–1.03; any two: HR 0.65; 95% CI, 0.52–0.82; and all three behaviors: HR 0.54; 95% CI, 0.43–0.69), in an inverse dose-response manner (P < 0.001 for trend). Population-attributable fraction for disability reduction in satisfying any one, any two, and all three behaviors were 4.0% (95% CI, −0.2 to 7.9%), 9.6% (95% CI, 4.8–14.1%), and 16.0% (95% CI, 8.7–22.8%), respectively.

Conclusion: Combining physical activity, dietary variety, and social interaction substantially enhances the impacts on preventing disability among older adults, with evidence of an inverse dose-response manner. Improving insufficient behavior elements through individual habits and preexisting social group activities may be effective in preventing disability in the community.

Background: Ginseng, an herbal remedy, has been commonly used in Asian countries to promote longevity and health for over 2000 years. However, the association of ginseng consumption on all-cause and cause-specific mortality is still unclear. We analyzed the association of total and major cause-specific mortality (cardiovascular disease (CVD), cancer, and other death) with consumption of ginseng (primarily American and white ginseng).

Methods: This study included 56,183 female participants with an average follow-up of 14.7 years in the Shanghai Women’s Health Study (SWHS), an ongoing prospective cohort study. Data were assessed via an in-person interview conducted at baseline recruitment. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for ginseng-mortality associations after adjusting for confounders.

Results: Compared with those who never used ginseng, regular ginseng use was associated with a significantly reduced all-cause mortality (HR=0.92, 95% CI: 0.87-0.98). This inverse association was seen primarily among those who consumed ginseng for perceived general health benefit (HR=0.90, 95% CI: 0.85-0.96). A significant dose-response association was observed between duration of ginseng use and total mortality (HR=0.85, for using ≥ 6 years vs never use, P for trend < 0.001), CVD mortality (HR=0.83, P for trend = 0.019), and other-cause mortality (HR=0.76, P for trend = 0.001). However, no dose-response association was observed between amount of ginseng consumption and mortality outcomes.

Conclusion: Regular ginseng consumption, particularly over a long duration, was associated with decreased risk of all causes of death, death due to CVD, and certain other diseases.

Background: Tobacco exposure during pregnancy is associated with several adverse outcomes in infants. We investigated the association between tobacco exposure during pregnancy (both active and second-hand) and various infections in infants up to 1 year.

Methods: This prospective cohort study used a fixed dataset (jecs-an-20180131) from the Japan Environment and Children’s Study of registered births in Japan during 2011–2014 that included 104,065 fetal records from enrolled pregnant women. Based on the participants’ responses to the questionnaire on smoking status, mothers were first divided into “Never smoked,” “Quit smoking,” and “Current smoker” groups and then into “No second-hand smoking (SHS)” and “SHS” groups. Infectious diseases included central nervous system infection, otitis media (OM), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), gastroenteritis (GI), and urinary tract infection. Adjusted odds ratios (aORs) and 95% confidence intervals (CI) were calculated using logistic regression analysis and adjusted for maternal, socioeconomic, and postnatal confounding factors.

Results: Among the 73,205 newborns enrolled, multivariable analysis revealed that the aOR (95% CI) of LRTI and GI was 1.20 (1.07-1.33) and 1.18 (1.04-1.35), respectively, for the “Current smoker with/without SHS” group compared with the “Never smoked without SHS” group. “Quit smoking without SHS” was not associated with the risk of LRTI. SHS was associated with an increased risk of OM, URTI, LRTI, and GI, especially with LRTI and GI.

Conclusions: Exposure to tobacco smoke during pregnancy was associated with an increased risk of OM, URTI, LRTI, and GI in infants during their first year of life.

Background: The association between changes in estimated glomerular filtration rate (eGFR) over time and the risk of stroke remains inconclusive. We aimed to evaluate the relation of eGFR change during the China Stroke Primary Prevention Trial (CSPPT) with the risk of first stroke during the subsequent post-trial follow-up.

Methods: A total of 11,742 hypertensive participants with two eGFR measurements (median measure interval, 4.4; interquartile range, 4.2–4.6 years) and without a history of stroke from the CSPPT were included in this analysis.

Results: Over a median post-trial follow-up of 4.4 years, 729 first strokes were identified, of which 635 were ischemic, 88 were hemorrhagic, and 6 were uncertain types of strokes. Compared with those with 1 to <2% per year increase in eGFR (with the lowest stroke risk), those with an increase in eGFR of ≥4% per year had significantly increased risks of first stroke (adjusted hazard ratio [HR] 1.96; 95% confidence interval [CI], 1.10–3.50) and first ischemic stroke (adjusted HR 2.14; 95% CI, 1.17–3.90). Similarly, those with a decline in eGFR of ≥5% per year also had significantly increased first stroke (adjusted HR 2.13; 95% CI, 1.37–3.31) and first ischemic stroke (adjusted HR 1.89; 95% CI, 1.19–3.02) risk. However, there was no significant association between eGFR change and first hemorrhagic stroke. A similar result was found when the change in eGFR was quantified as an absolute annual change.

Conclusion: In Chinese hypertensive patients, both the decline and increase of eGFR levels were independently associated with the risks of first stroke or first ischemic stroke.

Background: New tobacco products, particularly heated tobacco products (HTPs), have been introduced across several international markets as alternatives to combustible products, such as cigarettes. However, there are limited studies on physicians’ perceptions of HTPs. This study analyzes the awareness of HTPs among physicians and assesses their concerns and attitudes toward patients using HTPs.

Methods: A self-administered questionnaire was sent to a sample of 7,500 member physicians (6,000 male and 1,500 female) from the Japan Medical Association (JMA). The smoking status of physicians was categorized as never smokers, ever HTP smokers, current HTP smokers, and ever and current smokers of other products. Physicians’ awareness and attitudes toward patients using HTPs were analyzed using descriptive statistics. The correlation between the outcomes was examined using logistic regression models, whereas physicians’ concerns about HTPs were analyzed using descriptive statistics.

Results: Data were obtained from 5,492 physicians (21.9% women; aged 60.4±12.1 years) with a response rate of 74.6%. Overall, 76.7% of the physicians had awareness of HTP, and about half of whom asked patients about using HTPs. Physicians who took longer to discuss cessation were more likely to discourage patient use. Smoking status was associated with discouraging HTP use in patients. Physicians who had experience with HTP use were primarily concerned about the products’ long-term safety and less about product regulation.

Conclusions: Japanese physicians do not have sufficient information and knowledge about HTPs. Therefore, evidence-based guidelines are required to support physicians in advising patients against HTP use.

Background

Progress in reducing the global low birthweight (LBW) has been insufficient. Although the focus has been on preventing preterm birth, evidence regarding LBW in term births is limited. Despite its low preterm birth prevalence, Japan has a higher LBW proportion than other developed countries. This study aimed to examine the prevalence of LBW in term singleton births and its associated factors using a national database.

Methods

We retrospectively analyzed the data of neonates registered in the Japan Society of Obstetrics and Gynecology Successive Pregnancy Birth Registry System who were born 2013-2017. Exclusion criteria included stillbirths, delivery after 42 gestational weeks, and missing data. Logistic regression analyses were performed to investigate the maternal and perinatal factors associated with LBW in term singletons using the data of 715 414 singleton neonates.

Results

The overall prevalence of LBW was 18.3%, and 35.7% of LBWs originated from singleton term pregnancies. Multiple logistic regression analyses indicated that both modifiable and non-modifiable factors were independently associated with LBW in term neonates. The modifiable maternal factors included pre-pregnancy underweight, inadequate gestational weight gain, and smoking during pregnancy, while the non-modifiable factors included younger maternal age, nulliparity, hypertensive disorders of pregnancy, cesarean section delivery, female offspring, and congenital anomalies.

Conclusions

Using the Japanese pregnancy birth registry data, more than one-third of LBWs were found to originate from singleton term pregnancies. Both modifiable and non-modifiable factors were independently associated with LBW in term neonates. Prevention strategies on modifiable risk factor control will be effective in reducing LBW worldwide.

Background: Logistic regression models are widely used to evaluate the association between a binary outcome and a set of covariates. However, when there are few study participants at the outcome and covariate levels, the models lead to bias of the odds ratio (OR) estimated using the maximum likelihood (ML) method. This bias is known as sparse data bias, and the estimated OR can yield impossibly large values because of data sparsity. However, this bias has been ignored in most epidemiological studies.

Methods: We review several methods for reducing sparse data bias in logistic regression. The primary aim is to evaluate the Bayesian methods in comparison with the classical methods, such as the ML, Firth’s, and exact methods using a simulation study. We also apply these methods to a real data set.

Results: Our simulation results indicate that the bias of the OR from the ML, Firth’s, and exact methods is considerable. Furthermore, the Bayesian methods with hyper-ɡ prior modeling of the prior covariance matrix for regression coefficients reduced the bias under the null hypothesis, whereas the Bayesian methods with log F-type priors reduced the bias under the alternative hypothesis.

Conclusion: The Bayesian methods using log F-type priors and hyper-ɡ prior are superior to the ML, Firth’s, and exact methods when fitting logistic models to sparse data sets. The choice of a preferable method depends on the null and alternative hypothesis. Sensitivity analysis is important to understand the robustness of the results in sparse data analysis.

Background: We aimed to develop census-linked longitudinal mortality data for Japan and assess their validity as a new resource for estimating socioeconomic inequalities in health.

Methods: Using deterministic linkage, we identified, from national censuses for 2000 and 2010 and national death records, persons and deceased persons who had unique personal identifiers (generated using sex, birth year/month, address, and marital status). For the period 2010–2015, 1,537,337 Japanese men and women aged 30–79 years (1.9% in national census) were extracted to represent the sample population. This population was weighted to adjust for confounding factors. We estimated age-standardized mortality rates (ASMRs) by education level and occupational class. The slope index of inequality (SII) and relative index inequality (RII) by educational level were calculated as inequality measures.

Results: The reweighted sample population’s mortality rates were somewhat higher than those of the complete registry, especially in younger age-groups and for external causes. All-cause ASMRs (per 100,000 person-years) for individuals aged 40–79 years with high, middle, and low education levels were 1,078 (95% confidence interval [CI], 1,051–1,105), 1,299 (95% CI, 1,279–1,320), and 1,670 (95% CI, 1,634–1,707) for men, and 561 (95% CI, 536–587), 601 (95% CI, 589–613), and 777 (95% CI, 745–808) for women, respectively, during 2010–2015. SII and RII by educational level increased among both sexes between 2000–2005 and 2010–2015, which indicates that mortality inequalities increased.

Conclusions: The developed census-linked longitudinal mortality data provide new estimates of socioeconomic inequalities in Japan that can be triangulated with estimates obtained with other methods.

Background: Leaving children alone at home is considered child neglect in some countries but is not prohibited in Japan. We investigated the association between being left alone at home and dental caries of children aged 6–7 years in Japan.

Methods: The data on first graders in all 69 public elementary schools in Adachi, Tokyo, obtained from repeated cross-sectional surveys in 2015, 2017, and 2019 were analyzed. Caregivers answered the questionnaire, and the data were linked to the information on children’s dental caries evaluated in school dental health checkups (N = 12,029). Poisson regression analysis with propensity score matching (PSM) was applied to account for confounders.

Results: Leaving children alone at home for ≥1 hour during the weekdays was reported by 46.4% of the caregivers, which did not vary across years. The PSM analysis showed that, compared with children never being left alone at home, children being left alone at home for ≥1 time per week had more dental caries (mean ratio [MR] 1.11; 95% confidence interval (CI), 1.02–1.21; P = 0.016), while <1 time per week was not associated (MR 0.97; 95% CI, 0.92–1.03; P = 0.345). The difference between those being left alone at home for <1 time per week and those being left alone for ≥1 time per week was not significant after applying Bonferroni correction (MR 1.12; 95% CI, 1.00–1.26; P = 0.041).

Conclusion: Leaving children alone at home for ≥1 hour every week might be a risk factor for dental caries of children aged 6–7 years.

Background: Recent innovations in information and communication technology have made it possible to assess diet using web-based methods; however, their applicability in the general population remains unclear. Hence, we aimed to examine the applicability of a web-based 24-hour dietary recall (24HR) tool to large-scale epidemiological studies by determining the sampling rate and characteristics of randomly selected participants (partially entire population) from a Japanese cohort study.

Methods: In total, 5,013 individuals were recruited from a cohort of 21,537 individuals, and 975 agreed to participate in this study. The participants selected either self-administered web-based dietary 24HR (self-administered 24HR) or interviewer-administered telephone-based 24HR (interviewer-administered 24HR) as the method for the dietary assessment and answered questions regarding the acceptability of the system.

Results: The response rate of the 975 participants was 19.4%, and approximately 4.5% of the total study population. About half of them chose the self-administered 24HR (46.9%). The median time required for the self-administered and interviewer-administered 24HR was 25 and 27 minutes, respectively. In the self-administered 24HR, older people, regardless of sex, tended to require a longer time, and approximately 60% of the participants rated the ease of use of the system as “somewhat difficult” or “difficult.”

Conclusions: Characteristics of the participants in this study were not systemically different from those of the entire study population. Improvements in approach for the entering cooking details and the dish name selection may be necessary for better acceptability in order to be accepted as a self-administered 24HR.

Background: Serial weight decrease can be a prognostic predictor in chronic haemodialysis (HD) patients. We investigated the impact of long-term post-HD body weight (BW) changes on all-cause mortality among HD patients.

Methods: This longitudinal cohort study and post-hoc analysis evaluated participants of a previous randomised controlled trial conducted between 2006 and 2011 who were followed up until 2018. Weight change slopes were generated with repeated measurements every 6 months during the trial for patients having ≥5 BW measurements. Participants were categorised into four groups based on quartiles of weight change slopes; the median weight changes per 6 months were -1.02 kg, -0.25 kg, +0.26 kg, and +0.86 kg. Cox proportional hazard regression was used to evaluate differences in subsequent survival among the four groups. BW trajectories were plotted with a backward time-scale and multilevel regression analysis to visualise the difference in BW trajectories between survivors and non-survivors.

Results: Among the 461 patients, 404 were evaluated, and 168 (41.6%) died within a median follow-up period of 10.2 years. The Cox proportional hazard regression adjusted for covariates and baseline BW showed that a higher rate of weight loss was associated with higher mortality. The hazard ratios were 2.02 (1.28-3.20), 1.77 (1.10-2.85), 1.00 (reference), and 1.11 (0.67-1.83) for the first, second, third (reference), and fourth quartiles, respectively. BW trajectories revealed a significant decrease in BW in non-survivors.

Conclusions: Weight loss elucidated by serial BW measurements every 6 months is significantly associated with higher mortality among HD patients.

Background: Environmental and genetic factors are suggested to exhibit factor-based association with HDL-cholesterol (HDL-C) levels. However, the population-based effects of environmental and genetic factors have not been compared clearly. We conducted a cross-sectional study using data from the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study to evaluate the population-based impact of smoking, drinking, and genetic factors on low HDL-C.

Methods: Data from 11,498 men and women aged 35–69 years were collected for a genome-wide association study (GWAS). Sixty-five HDL-C-related SNPs with genome-wide significance (P < 5 × 10⁻⁸) were selected from the GWAS catalog, of which seven representative SNPs were defined, and the population-based impact was estimated using population attributable fraction (PAF).

Results: We found that smoking, drinking, daily activity, habitual exercise, egg intake, BMI, age, sex, and the SNPs CETP rs3764261, APOA5 rs662799, LIPC rs1800588, LPL rs328, ABCA1 rs2575876, LIPG rs3786247, and APOE rs429358 were associated with HDL-C levels. The gene-environmental interactions on smoking and drinking were not statistically significant. The PAF for low HDL-C was the highest in men (63.2%) and in rs3764261 (31.5%) of the genetic factors, and the PAFs of smoking and drinking were 23.1% and 41.8%, respectively.

Conclusions: The present study showed that the population-based impact of genomic factor CETP rs3764261 for low HDL-C was higher than that of smoking and lower than that of drinking.

Background: Little is known about whether insufficient moderate-to-vigorous physical activity (MVPA) and longer sedentary behavior (SB) are independently associated with estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD), whether they interact with known risk factors for CKD, and the effect of replacing sedentary time with an equivalent duration of physical activity on kidney function.

Methods: We examined the cross-sectional association of MVPA and SB with eGFR and CKD in 66,603 Japanese cohort study in 14 areas from 2004 to 2013. MVPA and SB were estimated using a self-reported questionnaire, and CKD was defined as eGFR <60 mL/min/1.73 m². Multiple linear regression analyses, logistic regression analyses, and an isotemporal substitution model were applied.

Results: After adjusting for potential confounders, higher MVPA and longer SB were independently associated with higher eGFR (P for trend MVPA <0.0001) and lower eGFR (P for trend SB <0.0001), and a lower odds ratio (OR) of CKD (adjusted OR of MVPA ≥20 MET·h/day, 0.76; 95% confidence interval [CI], 0.68–0.85 compared to MVPA <5 MET·h/day) and a higher OR of CKD (adjusted OR of SB ≥16 h/day, 1.81; 95% CI, 1.52–2.15 compared to SB <7 h/day), respectively. The negative association between MVPA and CKD was stronger in men, and significant interactions between sex and MVPA were detected. Replacing 1 hour of SB with 1 hour of physical activity was associated with about 3 to 4% lower OR of CKD.

Conclusions: These findings indicate that replacing SB with physical activity may benefit kidney function, especially in men, adding to the possible evidence on CKD prevention.

Background Cold exposure induces lower urinary tract symptoms including nocturia. Cold-induced detrusor overactivity can be alleviated by increasing skin temperature in rats. However, no study has shown an association between passive heating with hot-water bathing and nocturia among humans.

Methods We included 1,051 Japanese community-dwelling older adults (mean age 71.7 years) in this cross-sectional study from 2010 to 2014. The number of nocturnal voids was recorded in a self-administered urination diary. Nocturia was defined as ≥2 nocturnal voids. We evaluated bathing conditions in the participants’ houses.

Results Hot-water bathing (n = 888) was associated with a lower prevalence of nocturia than no bathing (n = 163), independent of potential confounders including age, sex, obesity, income, physical activity, diabetes, medication (diuretics, nondiuretic antihypertensives, and hypnotics), depressive symptoms, indoor/outdoor temperature, and day length (odds ratio [OR]: 0.68, 95% confidence interval [CI]: 0.48–0.97; p = 0.035). Compared with the quartile group with the longest bath-to-bed interval (range: 161–576 min), the second and third quartile groups (range: 61–100 and 101–160 min, respectively) were associated with a lower prevalence of nocturia, after adjusting for water temperature and bathing duration besides the same covariates (OR: 0.60, 95% CI: 0.38–0.96; p = 0.031 and OR: 0.59, 95% CI: 0.37–0.94; p = 0.025, respectively).

Conclusion Hot-water bathing, particularly with a bath-to-bed interval of 61–160 min, was significantly associated with a lower prevalence of nocturia among older adults.

Background: Work-family conflicts (total-WFCs) could associate with mental health, and having ikigai (a purpose of life) may mediate this association.

Methods: In a cross-cultural study of 4792 Japanese Aichi Workers’ Cohort study participants and 3109 Egyptian civil workers, the Midlife Development in the United States (MIDUS) questionnaire measured total-WFCs and Center for Epidemiological Studies Depression (CES-D) 11-item scale measured depression. Logistic regression models estimated odds ratios (ORs) of having depression and a high-ikigai across levels of total-WFCs (low, moderate, and high), and the PROCESS macro of Hayes tested the mediation effect.

Results: The prevalence of high total-WFCs, depression, and having a high-ikigai were 17.9%, 39.4%, and 70.1% in Japanese women, 10.5%, 26.8%, and 70.1% in Japanese men, 23.7%, 58.2%, and 24.7% in Egyptian women, and 19.1%, 38.9%, and 36.9% in Egyptian men. Compared with participants with low total-WFCs, the multivariable ORs (95% CIs) of depression in Japanese women and men with high total-WFCs were 4.11 (2.99-5.65) and 5.42 (4.18-7.02), and those in Egyptian women and men were 4.43 (3.30-5.95) and 4.79 (3.53-6.48). The respective ORs of having a high-ikigai were 0.46 (0.33-0.64) and 0.40 (0.31-0.52) in Japanese women and men and were 0.34 (0.24-0.48) and 0.28 (0.20-0.39) in Egyptian women and men. No interaction between total-WFCs and country was observed for the associations with depression or ikigai. Ikigai has mediated (up to 18%) the associations between the total-WFCs and depression, especially in Egyptian civil workers.

Conclusions: Total-WFCs were associated with depression, and having low-ikigai mediated these associations in Japanese and Egyptian civil workers.

Background: This cohort was established to evaluate whether 38-year radiation exposure (since the start of nuclear reactor operations) is related to cancer risk in residents near three nuclear power plants (NPPs).

Methods: This cohort study enrolled all residents who lived within 8 km of any of the three NPPs in Taiwan from 1978 to 2016 (n = 214,502; person-years = 4,660,189). The control population (n = 257,475; person-years = 6,282,390) from three towns comprised all residents having lived more than 15 km from all three NPPs. Radiation exposure will be assessed via computer programs GASPAR-II and LADTAP-II by following methodologies provided in the United States Nuclear Regulatory Commission regulatory guides. We calculated the cumulative individual tissue organ equivalent dose and cumulative effective dose for each resident. This study presents the number of new cancer cases and prevalence in the residence-nearest NPP group and control group in the 38-year research observation period.

Conclusions: TNPECS provides a valuable platform for research and opens unique possibilities for testing whether radiation exposure since the start of operations of nuclear reactors will affect health across the life course. The release of radioactive nuclear species caused by the operation of NPPs caused residents to have an effective dose between 10⁻⁷ and 10⁻³ mSv/year. The mean cumulative medical radiation exposure dose between the residence-nearest NPP group and the control group was not different (7.69; standard deviation, 18.39 mSv and 7.61; standard deviation, 19.17 mSv; P = 0.114).

Background: Tracking gestational weight gain (GWG) during pregnancy makes it possible to optimize pregnancy outcomes, and GWG growth curves are well suitable for this purpose. The GWG guidelines for Japanese were revised in 2021. However, currently, there are no GWG growth curves to guide women on how to gain weight to meet these guidelines.

Methods: Using data on 96,631 live births from the Japan Environment and Children’s Study (JECS), we created descriptive GWG percentile curves estimating the trajectory of GWG required to meet the GWG guidelines stratified by pre-pregnancy body mass index (BMI). For both analyses, Bayesian mixed models with restricted cubic splines adjusted for maternal characteristics were used.

Results: GWG curves substantially differed by pre-pregnancy BMI and were higher among multiparas and those with lower maternal age and with no previous disease. We estimated that underweight, normal weight, overweight, and obese women who gain 8.4 to 11.1 kg, 6.4 to 9.1 kg, 3.8 to 6.5 kg, and <1.9 kg at 30 weeks of gestation are on the trajectory to reach the new guidelines at 40 weeks of gestation.

Conclusions: We provide GWG percentiles curves for Japanese women, as well as GWG trajectory curves to meet the new GWG recommendations. These results may help pregnant women monitor weight during pregnancy.

Background: The present study analyzed the relation of disaster exposure prior to pregnancy with maternal characteristics and obstetric outcomes.

Methods: The participants were 13,148 pregnant women recruited from 2013 to 2017. The women were classified into three groups by the severity of housing damage caused by the Great East Japan Earthquake of 2011: group A, house was not destroyed/did not live in the disaster area; group B, half/part of the house was destroyed; and group C, house was totally/mostly destroyed. Maternal characteristics, hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), and gestational weeks were obtained using questionnaires and medical records. Multiple logistic regression analyses were performed to investigate the relation between disaster exposure and maternal characteristics, HDP, and GDM. A structural equation model was applied to investigate the relation of disaster exposure with HDP and gestational weeks.

Results: The homes of about 11% of the women were totally/mostly destroyed. For groups B and C compared with those in group A, the adjusted ORs for HDP were 1.04 and 1.26 (P for trend = 0.01), and for GDM were 0.89 and 1.14 (P for trend = 0.9), respectively. Pre-pregnancy body mass index (BMI) mediated 23.2% of the relation between disaster exposure and HDP. Disaster exposure was associated with gestational weeks.

Conclusion: Disaster exposure at least 2.5 years before pregnancy was found to be associated with maternal characteristics and the prevalence of HDP. Pre-pregnancy BMI mediated the relation between disaster exposure and the prevalence of HDP, and gestational weeks were reduced through HDP.

Background: The place of death and related factor, such as diseases, symptoms, family burden, and cost, has been examined, but social background and lifestyle were not considered in most studies. Here, we assessed factors that are associated with the place of death using the largest cohort study in Japan.

Methods: A total of 17,781 deaths from the cohort study were assessed. The study database was created from the Japan Public Health Center-based Prospective Study (JPHC Study), in which demographic data were collected from Japanese Vital Statistics. Adjusted odds ratios for home death were calculated using logistic regression.

Results: Multivariate analysis adjusted for various factors showed that unmarried status (odds ratio [OR] 2.4; 95% confidence interval [CI], 2.0–2.9), unemployed male (OR 1.3; 95% CI, 1.1–1.5), and high drinking level in male (OR 1.3; 95% CI, 1.1–1.6) were associated with home death. Regarding the cause of death, cardiovascular disease (OR 3.3; 95% CI, 2.9–3.8), cerebrovascular disease (OR 1.9; 95% CI, 1.6–2.2), and external factors (OR 4.1; 95% CI, 3.5–4.8) were significantly associated with home death, compared with cancer. The risk of death at home was significantly higher among unmarried subjects stratified by cause of death (cardiovascular disease: OR 3.2; 95% CI, 2.2–4.7; cerebrovascular disease: OR :5.1; 95% CI, 2.9–9.1; respiratory disease: OR 3.4; 95% CI, 1.6–7.6; and external factors: OR 2.3; 95% CI, 1.4–3.7), but for cancer, the risk of death at home tended to be higher among married participants.

Conclusions: This study found that various factors are associated with home death using the largest cohort study in Japan. There is a high possibility of home deaths in people with fewer social connections and in those with diseases leading to sudden death.

Background: Elevated resting heart rate (RHR) is associated with an increased risk of cardiovascular disease (CVD) and all-cause mortality. However, the findings of cohort studies differed. Thus, the impact of RHR on CVD mortality might be different according to the background of the population. Therefore, we examined the relationship of RHR and CVD mortality according to serum albumin (ALB) levels in a Japanese general population.

Methods: In total, 8,363 individuals without a history of CVD were followed for 24.0 years. The participants were divided into four groups according to the quartiles of RHR (Q1–Q4), and they were further classified into the high and low ALB groups based on a median value of 44 g/L. We estimated the multivariable-adjusted hazard ratios (HRs) of CVD mortality in each RHR group based on ALB levels, and the interaction between RHR and ALB groups on CVD mortality was evaluated.

Results: We found no significant association between RHR and CVD mortality. However, the Q4 of RHR was significantly associated with an increased risk for CVD mortality (HR 1.27; 95% confidence interval [CI], 1.02–1.57) in participants with a low ALB level. Meanwhile, the Q4 of RHR was significantly correlated with a decreased risk for CVD morality in those with a high ALB level (HR 0.61; 95% CI, 0.47–0.79) after adjusting for covariates. A significant interaction between RHR and ALB for CVD mortality was shown (P < 0.001).

Conclusions: The impact of RHR on CVD mortality differed according to ALB levels in a general Japanese population.

Background: Many epidemiological studies have reported the association between various social factors and health status in mothers during and after pregnancy. However, little is known about their joint and longitudinal impact. We examined the association of lack of social support and trust during pregnancy and at 2.5 years postpartum with health status in mothers.

Methods: To adequately address time-varying exposure, marginal structural models were fitted to a pseudopopulation constructed using inverse probability weighting. The model included records of 90,071 mothers participating in the Japan Environment and Children’s Study. Social support and trust were measured using a 9-item questionnaire (Q1–9). Mental and physical health were measured using Mental and Physical Component Summary scores from the 8-item Short-Form Health Survey.

Results: For the Mental Component Summary, the magnitude of the effect estimate was largest when participants lacked close friends/neighbors (Q4) at only 2.5 years postpartum (effect estimate, −6.23), followed by a lack in emotional support (Q2) at the same time point (effect estimate, −4.94). For the Physical Component Summary, effect estimates were negligible. The magnitude of the effect estimates of lack of social support and trust tended to be larger when there was a lack at only 2.5 years postpartum than at both time points.

Conclusions: These findings suggest that, after childbirth, a loss in social support, particularly in an emotional aspect, carries high risk, especially for mental health. Our results highlight the importance of supporting mothers for more than a few years after pregnancy.

Background: The CD4 cell count of patients during diagnosis and distribution of CD4 cell counts in the patient population are important to understand infection-diagnosis interval and incidence rate of human immunodeficiency virus (HIV) infection, respectively. However, this information has not been published in Japan. This study aimed to describe the change in CD4 cell count trends and clarify the change in patients’ characteristics in association with the CD4 cell count information.

Methods: A descriptive study was conducted to analyze the medical records of patients with HIV who visited one of the largest acquired immunodeficiency syndrome (AIDS) core hospitals in western Japan. The basic characteristics, CD4 cell counts, viral loads, and diagnosis-treatment intervals between the first (2003–2010) and second (2011–2017) halves of the study duration were compared.

Results: The distribution of CD4 cell counts significantly changed between 2003–2010 and 2011–2017 (χ² = 20.42, P < 0.001). The proportion of CD4 cell count <200 cells/mm³ increased (38.8% in 2003 to 45.9% in 2017), whereas CD4 cell count ≥500 cells/mm³ decreased (19.4% in 2003 to 12.2% in 2017). Moreover, the distributions of age groups, history of HIV screening test, patient outcomes, HIV viral load, and diagnosis-treatment interval also significantly changed (χ² = 25.55, P < 0.001; χ² = 8.37, P = 0.015; χ² = 6.07, P = 0.014; χ² = 13.36, P = 0.020; χ² = 173.76, P < 0.001, respectively).

Conclusion: This study demonstrated the fundamental trends of the HIV epidemic in Osaka, Japan between 2003–2010 and 2011–2017 and indicated that the incidence rate of HIV was decreasing in Japan.

Background: Mapping disease rates is an important aspect of epidemiological research because it helps inform public health policy. Disease maps are often drawn according to local administrative areas (LAAs), such as counties, cities, or towns. In LAAs with small populations, disease rates are unstable and are prone to appear extremely high or low. The empirical Bayes methods consider variance differences among different LAAs, thereby stabilizing the disease rates. The methods of kriging break the constraints of geopolitical boundaries and produce a smooth curved surface in the form of contour lines, but the methods lack the stabilizing effect of the empirical Bayes methods.

Methods: An easy-to-implement stabilized kriging method is proposed to map disease rates, which allows different errors in different LAAs.

Results: Monte Carlo simulations revealed that the stabilized kriging method had smaller symmetric mean absolute percentage error than three other types of methods (the original LAA-based method, empirical Bayes methods, and traditional kriging methods) in nearly all scenarios considered. Real-world data analysis of oral cancer incidence rates in men from Taiwan demonstrated that the age-standardized rates in the central mountainous sparsely-populated region of Taiwan were stabilized using our proposed method, with no more large differences in numerical values, whereas the rates in other populous regions were not over-smoothed. Additionally, the stabilized kriging map had improved resolution and helped locate several hot and cold spots in the incidence rates of oral cancer.

Conclusions: We recommend the use of the stabilized kriging method for mapping disease rates.

Background: The counterfactual definition of confounding is often explained in the context of exchangeability between the exposed and unexposed groups. One recent approach is to examine whether the measures of association (e.g., associational risk difference) are exchangeable when exposure status is flipped in the population of interest. We discuss the meaning and utility of this approach, showing their relationships with the concept of confounding in the counterfactual framework.

Methods: Three hypothetical cohort studies are used, in which the target population is the total population. After providing an overview of the notions of confounding in distribution and in measure, we discuss the approach from the perspective of exchangeability of measures of association (e.g., factual associational risk difference vs. counterfactual associational risk difference).

Results: In general, if the measures of association are non-exchangeable when exposure status is flipped, confounding in distribution is always present, although confounding in measure may or may not be present. Even if the measures of association are exchangeable when exposure status is flipped, there could be confounding both in distribution and in measure. When we use risk difference or risk ratio as a measure of interest and the exposure prevalence in the population is 0.5, testing the exchangeability of measures of association is equivalent to testing the absence of confounding in the corresponding measures.

Conclusions: The approach based on exchangeability of measures of association essentially does not provide a definition of confounding in the counterfactual framework. Subtly differing notions of confounding should be distinguished carefully.

Background: Validation studies of diabetes definitions using nationwide healthcare databases are scarce. We evaluated the validity of diabetes definitions using disease codes and antidiabetic drug prescriptions in the Japanese Diagnosis Procedure Combination (DPC) data via medical chart review.

Methods: We randomly selected 500 records among 15,334 patients who participated in the Japan Public Health Center-Based Prospective Study for the Next Generation in Yokote City and who had visited a general hospital in Akita between October 2011 and August 2018. Of the 500 patients, 98 were linked to DPC data; however, only 72 had sufficient information in the medical chart. Gold standard confirmation was performed by board-certified diabetologists. DPC-based diabetes definitions were based on the International Classification of Diseases, 10th Revision codes and antidiabetic prescriptions. Sensitivity, specificity, and the positive and negative predictive values (PPV and NPV, respectively) of DPC-based diabetes definitions were evaluated.

Results: Of 72 patients, 23 were diagnosed with diabetes using chart review; 19 had a diabetes code, and 13 had both a diabetes code and antidiabetic prescriptions. The sensitivity, specificity, PPV, and NPV were 89.5% (95% confidence interval [CI], 66.9–98.7%), 96.2% (95% CI, 87.0–99.5%), 89.5% (95% CI, 66.9–98.7%), and 96.2% (95% CI, 87.0–99.5%), respectively, for (i) diabetes codes alone; 89.5% (95% CI, 66.9–98.7%), 94.3% (95% CI, 84.3–98.8%), 85.0% (95% CI, 62.1–96.8%), and 96.2% (95% CI, 86.8–99.5%) for (ii) diabetes codes and/or prescriptions; 68.4% (95% CI, 43.4–87.4%), 100% (95% CI, 93.3–100%), 100% (95% CI, 75.3–100%), and 89.8% (95% CI, 79.2–96.2%) for (iii) both diabetes codes and prescriptions.

Conclusions: Our results suggest that DPC data can accurately identify diabetes among inpatients using (i) diabetes codes alone or (ii) diabetes codes and/or prescriptions.

Background: Increasing number of studies have suggested the time to first cigarette after waking (TTFC) have significant positive effect on respiratory diseases. However, few of them focused on the Chinese population. This study aims to estimate the impact of TTFC on the prevalence of chronic respiratory diseases (CRD) in Chinese elderly and explore the association in different sub-populations.

Methods: Cross-sectional data of demographic characteristics, living environment, smoking-related variables, and CRD were drawn from the Chinese Longitudinal Healthy Longevity Survey in 2018. Multivariate stepwise logistic regression analyses were conducted to examine the association of the TTFC with the prevalence of CRD.

Results: This study includes 13,208 subjects aged 52 years and older, with a mean age of 85.3 years. Of them, 3,779 participants were ex- or current smokers (44.9% had the TTFC ≤30 minutes, 55.1% >30 minutes) and 1,492 had suffered from CRD. Compared with non-smokers, participants with TTFC ≤30 minutes seemed to have higher prevalence of CRD (OR 1.97; 95% CI, 1.65–2.35) than those with TTFC >30 minutes (OR 1.70; 95% CI, 1.44–2.00), although the difference was statistically insignificant (P_interaction = 0.12). Compared with TTFC >30 minutes, TTFC ≤30 minutes could drive a higher prevalence of CRD among female participants, those aged 90 years and older, urban residents, and ex-smokers (P_interaction < 0.05).

Conclusions: Shorter TTFC relates to higher prevalences of CRD in Chinese older females, those aged 90 years and older, urban residents, and ex-smokers. Delaying TTFC might partially reduce its detrimental impact on respiratory disease in these specific subpopulations.

Background: In 2012, the Korean government expanded dental insurance for the elderly to promote improved access to dental care. We examined the causal effect of this policy on dental care needs, focusing on low-income older adults.

Methods: We compared data before and after policy implementation using double difference (DD) and triple difference (DDD) analyses. We used the nationally representative data from the Korea National Health and Nutrition Examination Survey from 2010 and 2016–2018. Individuals aged ≥65 years were included in the treatment group, and individuals aged <65 years were included in the control group.

Results: Dental insurance expansion was associated with a paradoxical increase in perceived unmet dental needs among elderly individuals (8.8 percentage points increase, 95% CI: 4.7 to 13.0). However, there were improvements in dental prosthetics outcomes (denture wearing [4.0 percentage points, 95% CI: 0.2 to 7.9] and dental implants [5.0 percentage points, 95% CI: 2.1 to 7.9]; P < 0.01). Upon analyzing low-income elderly individuals using DDD analysis, we found that the insurance expansion led to a 21.6% smaller increase in unmet dental needs among low-income adults, compared to high-income adults (95% CI, −35.0 to −8.5; P < 0.01).

Conclusions: Dental insurance expansion in South Korea resulted in improvements in access to dental prosthetic services overall. It also led to a smaller increase in unmet dental needs among low-income older adults, compared to high-income adults.

Background: Basic and instrumental activities of daily living (BADL and IADL, respectively) are known predictors of mortality. However, the relationship between higher-level functional capacity (HLFC) and mortality and related sex differences have rarely been investigated.

Methods: A prospective population-based cohort study was conducted in 1,824 older residents (≥65 years) with independent BADL from 300 randomly selected areas in Japan from 1995, and the participants were followed up until 2010. Using the Cox proportional hazards model, the relationship between HLFC and mortality risk was investigated, with adjustment for possible confounders. HLFC was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence. Baseline data were collected using a questionnaire or by home-visit interviews.

Results: During an average 12.2-year follow-up, all-cause death was observed in 836 (45.8%) participants. Impaired HLFC was significantly associated with mortality (hazard ratio [HR] 1.37; 95% confidence interval [CI], 1.13–1.65). Lower social role was significantly associated with higher mortality risk in men (HR 1.38; 95% CI, 1.13–1.68). Lower IADL and intellectual activity were significantly associated with higher mortality risk in women (HR 1.50; 95% CI, 1.15–1.95 and HR 1.46; 95% CI, 1.19–1.79, respectively). The relationship between HLFC and mortality risk showed a similar tendency among cardiovascular diseases, stroke, cancer, and pneumonia.

Conclusion: Impaired HLFC was associated with a high risk of all-cause mortality among community-dwelling older people with independent BADL. In particular, social role in men and IADL and intellectual activity in women were associated with long-term mortality risk.

Background: Anger has been suggested as a risk factor for stroke. Perceived social support (PSS) may relieve anger, thus reducing the risk of stroke; however, evidence supporting this is limited. We aimed to examine whether PSS modifies the risk of stroke associated with anger expression.

Methods: A cohort study was conducted among 1,806 community residents aged 40–74 years who received a cardiovascular risk survey, including anger expression, in 1997. A Cox proportional hazards model was applied to the participants with low and high PSS to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of the risks of total stroke and its subtypes based on total anger expression after adjusting for known stroke risk factors.

Results: The median follow-up duration was 18.8 years, with 51 incident strokes. Among the participants with low PSS, anger expression had a positive association with the total stroke risk: The multivariable HR per standard deviation increment of total anger expression was 1.43 (95% CI, 1.13–1.82). In contrast, no association was identified among those with high PSS. The corresponding HR was 0.83 (95% CI, 0.49–1.40), with a significant interaction between low and high PSS (P = 0.037). Similar associations regarding the risk of ischemic stroke were found.

Conclusions: We found an increased risk of stroke associated with anger expression among the participants with low PSS, but not among those with high PSS. Our results suggest that PSS might mitigate the risk of stroke associated with anger.