Journal of Epidemiology最新文献

The Tokyo Adolescent Mental Health Study (TAMHS) is an ongoing, school-based longitudinal cohort designed to elucidate the developmental trajectories of mental health among adolescents in Japan and to inform evidence-based strategies for promoting adolescent well-being. Since its inception in 2009, TAMHS has annually tracked adolescents aged 12-18 from a Tokyo secondary school known for its tradition of enrolling twins and triplets. Participants are followed for up to six years. As of 2024, 2,435 adolescents (1,211 boys, 1,196 girls, 28 unspecified), including 551 twins and triplets (22%), have been enrolled. This unique sample composition allows for rigorous comparisons between singletons and multiples to examine the impact of birth plurality on neurodevelopmental and mental health trajectories. High annual retention (96.2%-99.2%) ensures the integrity of longitudinal analyses. Data are collected through self-report questionnaires covering demographics, physical and mental health status, daily habits and lifestyle behaviors, social relationships, behavioral problems, healthcare access, and social and environmental determinants of health. The study has yielded important insights into associations between adolescent lifestyle behaviors and mental health outcomes.

Background: The Diagnosis Procedure Combination (DPC) database is Japan's most widely used administrative inpatient dataset, supporting epidemiological and health services research. While its validity is established for various diagnoses and procedures, accuracy for intensive care unit (ICU) variables has not been directly evaluated using a clinical registry as the gold standard.

Methods: We conducted a multicenter retrospective validation study using four Japanese ICUs. Patient records from the national ICU registry, the Japanese Intensive Care Patients Database (JIPAD), were matched with corresponding DPC data, retaining only successfully matched patients to evaluate coding accuracy rather than case ascertainment. We assessed binary variables (demographics, comorbidities, diagnoses, interventions, ICU admission, mortality) and continuous variables (demographics, Sequential Organ Failure Assessment [SOFA] scores). We calculated sensitivity and specificity for binary variables and intraclass correlation coefficients (ICCs) for continuous variables.

Results: We included 14,070 ICU admissions. Most binary variables, including demographics, major diagnostic categories, ICU interventions, and mortality, had high sensitivity and specificity (≥80%). Comorbidity specificity exceeded 95%, but sensitivity was <30% for several diseases. Sensitivity was 83.3% for invasive mechanical ventilation but low for noninvasive positive pressure ventilation (5.5%) and high-flow nasal cannula (36.1%), although specificity was high across respiratory supports (97.3%-99.9%). SOFA scores showed moderate agreement (ICC, 0.61). Sensitivity/specificity were 99.1%/100.0% for in-hospital mortality and 96.2%/99.9% for ICU mortality.

Conclusions: The DPC administrative inpatient database accurately captures most key ICU variables, but comorbidities, noninvasive respiratory support, and SOFA scores require caution. These findings support its use for ICU clinical and epidemiological research in Japan.

Background: Seasonal influenza is a recurrent respiratory infection, and timely detection is essential for public health. In Japan, surveillance is conducted through sentinel medical institutions under the National Epidemiological Surveillance of Infectious Diseases (NESID). Recently, access to large claims databases, such as the JMDC claims database (JMDCdb), has increased. While both are sample-based systems, JMDCdb covers a much larger population. We aimed to assess consistency between these sources in estimating influenza cases and the effective reproduction number (R_t), and to explore their utility in epidemic analysis.

Methods: We analyzed data from week 36 of 2016 to week 35 of 2019. Influenza cases were estimated from NESID (reported cases and cases per sentinel) and JMDCdb (cases with influenza-related diagnoses and antiviral prescriptions). Daily infection counts were derived to estimate R_t.

Results: Although minor differences appeared at epidemic peaks, estimates from NESID reports aligned well with JMDCdb. Estimates based on cases per sentinel were lower. R_t values were consistent across data sources. R_t exceeded 1.0 when cases per sentinel surpassed 0.2-0.3. Using a threshold of 0.25 cases per sentinel enabled detection of epidemic onset 4-5 weeks earlier than current standards.

Conclusion: Claims data such as those from JMDCdb may be useful for retrospective examination of influenza trends. Moreover, a detailed analysis of the number of cases reported per sentinel suggested the potential to propose threshold values that enable earlier prediction of epidemics than conventional criteria.

Background: During the COVID-19 pandemic, global influenza activity sharply declined due to extensive non-pharmaceutical interventions (NPIs). Understanding how influenza activity rebounded after these interventions were lifted is critical for informing future respiratory virus control strategies.

Methods: We conducted a descriptive analysis of the temporal characteristics of weekly number of influenza-like illness (ILI) cases, ILI%, influenza-positive cases, and influenza-positive rates. Poisson log-link regression models, incorporating meteorological factors using data from 2013 to 2019, were established to predict the weekly influenza-positive rate under a counterfactual scenario without COVID-19 interventions in 2022-2023.

Results: Our findings indicate that the cancellation of COVID-related non-pharmacological interventions (NPIs) had a notable impact on increasing influenza transmission. Children under 5 years old exhibited the highest ILI cases. The influenza positivity rate surged to 34.35% during the pandemic relaxation, surpassing pre-pandemic (24.53%) and pandemic (9.56%) rates. During the pre-COVID-19 period, various influenza virus subtypes were co-circulated, with the predominant subtype varying. However, during the COVID-19 pandemic period, the dominant strains were influenza A/H1N1 and influenza B/Victoria lineage, while influenza A/H3N2 predominated in the pandemic relaxation period.

Conclusion: The marked resurgence of influenza activity in Shenzhen following the lifting of COVID-related NPIs underscores the need for sustained surveillance and preparedness for concurrent or sequential respiratory virus outbreaks.

Background: Socioeconomic inequalities in disability-free life span have been widening. We evaluated the mediating role of multiple modifiable risk factors, including tooth loss, on socioeconomic inequalities in disability onset and mortality among Japanese older adults.

Methods: This prospective cohort study utilised data from the Japan Gerontological Evaluation Study, targeting adults aged ≥65 years. The 2013 baseline questionnaire survey participants were followed until 2022 (n = 48,474; median follow-up 9.0 years). Time-varying mediators were also assessed in questionnaire surveys in 2016 and 2019. Discrete-time survival analysis estimated the association of socioeconomic status (SES) -a standardised principal component score incorporating household income, wealth, and years of education-with disability or mortality onset. The Karlson-Holm-Breen method decomposed total effects into pathways through 11 mediators, including tooth loss and major risk factors for disability and mortality.

Results: During the follow-up, 29.1% became disabled or died. Compared to the highest SES group, the lowest SES quartile group exhibited hazard ratios (95% confidence intervals [CI]) of 1.26 (1.19, 1.34) for disability or mortality. Tooth loss exhibited the second largest indirect effect (proportion mediated [95% CI], 12.4% [8.0, 17.2]), following moderate depression (16.0% [11.7, 21.5]). Tooth loss exhibited the strongest association with SES, attributing to the large indirect effect.

Conclusion: The findings suggest that tackling inequalities in tooth loss may be an effective way to reduce socioeconomic inequalities in a disability-free life span.

Background: The Ministry of Health, Labour, and Welfare in Japan has published a meal-based dietary guideline (Healthy Meal); however, its relationship with health outcomes remains unclear. This observational study examined the association between adherence to Healthy Meal and all-cause and cause-specific mortalities.

Methods: We analyzed data from the Japan Public Health Center-based Prospective Study (JPHC Study) with a mean follow-up of 19.0 years, including 40,222 men and 47,350 women aged 45-75 years with no history of cancer, stroke, ischemic heart disease, chronic liver disease, or kidney disease. Adherence to Healthy Meal was scored using dietary intake from a validated food frequency questionnaire. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortalities across score quartiles.

Results: A higher Healthy Meal adherence score was significantly associated with a lower risk of all-cause mortality. The multivariable-adjusted HRs for the highest versus the lowest adherence group were 0.86 (95% CI, 0.82-0.91, P < 0.001 for trend) in men and 0.92 (95% CI, 0.87-0.98, P = 0.005 for trend) in women. Significant associations with a lower risk of cerebrovascular disease and respiratory disease mortalities were observed in both sexes. In contrast, significant associations were observed for cancer, cardiovascular disease, and heart disease mortalities in men only.

Conclusion: Higher adherence to the Japanese meal-based dietary guideline was associated with a lower risk of all-cause, cerebrovascular disease, and respiratory disease mortalities in Japanese men and women, and cancer, cardiovascular disease, and heart disease mortalities in men only.

Background: One of the factors for not achieving a reduced salt diet may be the difficulties in screening individuals according to their quantitative salt consumption. Accordingly, we examined the performance of a simplified 13-item salt check sheet as a quantitative tool for screening excessive salt intake by comparing with the salt intake amount measured by 24-hour urinary sodium (salt equivalent g/day) excretion.

Methods: One hundred fifty-four participants (57 males and 97 females) from Kanagawa, Tokyo, and Nara Prefectures in Japan were included. In this study, which the design is a cross-sectional validation study, the salt intake amount was used as a diagnostic criterion, and corresponding receiver operating characteristic (ROC) curves were prepared based on the sensitivity and specificity of each score of the salt check sheet.

Results: The average salt intake were 13.5 and 10.2 g/day for males and females, respectively. When using the total score, among males, the area under the ROC curve (AUC) was moderate (0.702; 95% confidence interval [CI], 0.543-0.862), confirming its value as a diagnostic tool for salt intake of ≥10 g/day. In females, the AUCs were low for any criteria. When score calculation item was limited to three that contributed to the higher salt intake in this population, the AUC for ≥10 g salt/day was moderate (0.700; 95% CI, 0.595-0.805).

Conclusion: The salt check sheet was found to be useful in screening for excessive salt intake only in males. For females, it was suggested that it could be used only when three specific items are used.

Objectives: This scoping review summarizes and evaluates evidence from Japan on prospective relationships of sedentary behavior (too much sitting, as distinct from too little physical activity) with health outcomes, forming the basis for Japan's new sedentary behavior guidelines. It also identified evidence gaps and provided recommendations for future public health guidelines.

Methods: A systematic search was conducted in PubMed, Web of Science, CINAHL, and MEDLINE for English-language, peer-reviewed longitudinal studies on sedentary behavior and health outcomes in apparently healthy Japanese adults published between 2000 and 2023. The search strategy was developed based on sedentary behavior measures, study design, and study population. Two independent reviewers screened titles, abstracts, and full texts. Data were synthesized narratively, with a quality assessment performed.

Results: Twenty-seven relevant studies were identified, all but one published after 2013. About half focused on middle-aged and older adults, primarily using self-report questionnaires. Many studies were large cohorts (>10,000 participants) with follow-ups of more than 10 years. Studies varied widely in physical activity indicators, confounders, time classifications, and cutoff values for sedentary behavior. The studies examined 29 health outcomes, primarily all-cause mortality, cancer incidence, and cancer mortality. Most studies reported at least partial evidence of harmful associations between sedentary behavior and health outcomes, though only eight were rated as good quality.

Conclusion: There is sufficient evidence to support minimizing sedentary time to promote health in Japanese adults. However, due to the limited number of high-quality studies, the specificity and dose-response relationship between sedentary behavior and health outcomes remain unclear.

Background: Insulin resistance in adipocytes, manifested as high basal circulating free fatty acid (FFA) is thought to contribute to the development of type 2 diabetes mellitus (T2DM). However, the association between adipocyte insulin resistance (Adipo-IR) index and T2DM has rarely been explored in prospective studies. We examined this association in a middle-aged Japanese workers' cohort. Since the association may differ according to the degree of overall adiposity, the analysis was stratified by the presence of overweight/obesity defined with body mass index (BMI).

Methods: A total of 3,257 subjects (men 2501, women 756) aged 35-66 years were followed-up for up to 17 years. T2DM incidence was defined as fasting blood glucose level ≥126 mg/dL, glycated hemoglobin level ≥6.5%, or self-reported initiation of glucose-lowering medications. Adipo-IR was calculated as the product of FFA (mmol/L) and insulin (pmol/L) obtained from baseline fasting blood samples and divided into sex- and BMI category (<25 or ≥25 kg/m²)-specific tertiles. Cox-proportional hazards model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for age, BMI, smoking status, physical activity, drinking habit, and family history of diabetes.

Results: During a median of 14.6 years of follow-up, 365 developed T2DM. Compared with the lowest tertile, T2DM risk was significantly increased among the highest tertile category in overweight/obese men (HR 2.94; 95% CI, 1.76-4.90) and women (HR 4.24; 95% CI, 1.08-16.61).

Conclusion: Adipo-IR was positively associated with T2DM risk in overweight/obese men and women.