Journal of Epidemiology最新文献

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.

Background: Loneliness is prevalent among older adults and is linked to physical and mental health problems. Community social capital has been suggested to mitigate its impact, but its heterogeneity across socioeconomic groups has not been explored.

Methods: We analysed cross-sectional data from the 2019 Japan Gerontological Evaluation Study (JAGES) with 24,206 participants aged 65 years or older. Loneliness was measured using University of California, Los Angeles's 3-item scale, and community social capital was assessed using civic participation, social cohesion, and reciprocity. Modified Poisson regression models were used, adjusting for sociodemographic factors and individual responses to the questions on social capital. Interaction effects of gender, education, and income were examined.

Results: Higher levels of community social cohesion (prevalence ratio [PR] 0.84; 95% confidence interval [CI], 0.75-0.94) and community reciprocity (PR 0.64; 95% CI, 0.51-0.80) were inversely associated with loneliness. The relationship between community civic participation and loneliness varied by educational attainment. Interaction analysis indicated that individuals with higher education levels (≥13 years) who engaged in community civic participation had a lower prevalence of loneliness (PR 0.74; 95% CI, 0.57-0.95) compared to those with lower education levels. No clear interactions were observed for gender or income.

Conclusion: Community social capital, particularly social cohesion and reciprocity, was associated with lower levels of loneliness among older adults. The effect of civic participation differed by education, showing a stronger negative association among individuals with higher education levels (≥13 years). Tailored interventions accounting for educational backgrounds are needed while promoting social capital universally.

Background: Pre-pregnancy underweight (BMI<18.5 kg/m²) is notably prevalent among reproductive-aged Japanese women, affecting approximately 20%, compared to less than 10% in Western countries. However, its overall impact on maternal and infant outcomes in Japanese populations has not been systematically evaluated.

Methods: We conducted a systematic review and meta-analysis following PRISMA 2020 guidelines. MEDLINE, EMBASE, CINAHL, PsycINFO, Cochrane Library, and Ichushi were searched from inception to February 2024. Cohort and case-control studies examining associations between pre-pregnancy underweight and perinatal outcomes in Japanese women with singleton pregnancies were included. Primary outcomes were low birth weight (LBW), small for gestational age (SGA), and preterm birth (PTB). Random-effects models calculated pooled odds ratios (ORs) with 95% confidence intervals (CIs).

Results: Thirty-four studies were analyzed. Pre-pregnancy underweight significantly increased risks of LBW (OR=1.61, 95% CI: 1.38-1.86), SGA (OR=1.59, 95% CI: 1.55-1.63), and PTB (OR=1.23, 95% CI: 1.19-1.26). Mean birth weight was 115.02g lower (95% CI: -128.05 to -101.99) in underweight mothers.

Conclusions: Pre-pregnancy underweight among Japanese women is significantly associated with increased risks of adverse perinatal outcomes. Notably, these elevated risks persist despite the high background prevalence of underweight, suggesting that their adverse effects are not diminished in populations where it is more common. These findings underscore the importance of increasing awareness of preconception care and emphasize the need to optimize pre-pregnancy weight.

Background: Herpes simplex virus encephalitis(HSE) is a rare but life-threatening condition. While the disease has been well characterized in Western countries, large-scale epidemiological data from Japan are lacking.

Methods: Using the Diagnosis Procedure Combination(DPC) Study Group database, we identified patients hospitalized with HSE between July 2010 and March 2023. Patients were identified using ICD-10 codes. Nationwide incidence was estimated by multiplying the observed case counts by the annual ratio of total discharges in the national MHLW-DPC database to those in the DPC Study Group. We used generalized estimating equations (GEE) to account for clustering within hospitals in multivariable models. In-hospital mortality and functional and neurological outcomes were assessed. Multivariable logistic regression identified prognostic factors.

Results: A total of 6,788 patients were identified. The annual incidence of HSE ranged from 5.7 to 8.2 per 100,000 hospitalizations. Overall, in-hospital mortality was 6.0%. Of 6,378 survivors, 2,295 (36.0%) had a Barthel Index score ≤90 and 1,602 (25.1%) had impaired consciousness (Japan Coma Scale ≥1) at discharge. A composite poor outcome (death or impaired consciousness) occurred in 2,012 (29.6%). Older age (especially ≥80 years), impaired consciousness at presentation, and comorbidities such as congestive heart failure, chronic renal disease, malignancy, and underweight status were associated with in-hospital mortality and poor outcomes.

Conclusion: This multicenter analysis of HSV encephalitis in Japan showed that HSV encephalitis in Japan was associated with substantial disability among survivors, in addition to non-negligible mortality. Our findings highlight the need for post-acute rehabilitation to reduce the burden of residual disability.

Background: The impact of the coronavirus disease 2019 (COVID-19) pandemic on changes in physical activity, particularly diurnal patterns, remains unclear. We investigated temporal changes in daily steps before and after the emergency declaration in Japan during the COVID-19 pandemic.

Methods: Nationwide de-identified data from users of a physical activity-promoting smartphone application were collected. Daily and hourly steps were measured using smartphones from January 2019 to September 2020. Linear mixed models estimated changes in steps before, during, and after the April and May 2020 emergency declaration relative to 2019, involving 3,480 users (daily steps) and 3,402 users (hourly steps).

Results: Compared to the 2019 baseline, daily steps decreased during the emergency declaration (April: -1115 steps/day [95% confidence interval, -1233 to -998]) and only partly recovered thereafter (July: -496 steps/day [-609, -382]). This decline was greater among participants aged 18-39 (P for interaction < 0.05). By time of day, steps significantly decreased during weekday morning commutes and at night (e.g., 21:00: -136 steps/hour [-153, -119]) and during weekend days and late evenings (e.g., 12:00: -173 steps/hour [-196, -151]). After the declaration was lifted, step counts recovered but were still lower at night (e.g., 21:00 on weekends: -120 steps/hour [-135, -106]).

Conclusions: Daily steps decreased after the emergency COVID-19 declaration in Japan. Even after the emergency period ended, there was a persistent population-level decline in daily steps, with a partial shift in the diurnal pattern. Efforts are needed not only to restore but also to further promote physical activity beyond pre-pandemic levels.

Background: In April 2016, Japan mandated higher-level hospitals (i.e., Special Functioning Hospitals [SFHs] and Regional Medical Care Support Hospitals [RMCSHs] with ≥ 500 beds) to charge additional fees for non-referral first visits to facilitate hospital function differentiation. The mandate expanded to RMCSHs with 400-499 beds and 200-399 beds in April 2018 and April 2020, respectively. We investigated changes in referral rates (proportion of referred to first-visit patients) before and after the fee's implementation.

Methods: Using a community-based insurance claims database from a single prefecture in Japan, we extracted claims for first visits to hospitals with ≥ 200 beds between April 2014 and March 2022 and calculated monthly referral rates to five hospital groups (SFHs, RMCSHs with ≥ 500, 400-499, and 200-399 beds, and non-designated hospitals with ≥ 200 beds). We conducted a controlled interrupted time-series analysis by hospital category, treating non-designated hospitals as controls.

Results: Of 405,087 first-visit patients (mean age 54.9 years [standard deviation 20.2]; 53.2% female), 157,734 (38.9%) had a referral. The average referral rate to SFHs was high pre-mandate and did not increase. With the mandate, referral rates to RMSCHs with ≥ 500 beds and 400-499 beds rose by 5.10% (95% confidence interval: 1.84-8.35) in 2016 and 4.49% (0.28-8.70) in 2018, respectively, and stabilized afterward. Referral rates to RMCSHs with 200-399 beds remained unchanged.

Conclusions: Average referral rates increased when the additional fee was mandated for RMCSHs with ≥ 400 beds, although the influence on health outcomes remains unclear.

Medical claims data are increasingly used in epidemiological studies, but are inadequately validated to ensure their reliability in identifying diseases. We developed the Claims data Learning & Enhancing for Algorithm Refinement (CLEAR) Study as a database platform to enable the systematic, low-cost implementation of validation studies in Japan. The CLEAR Study links routinely generated medical claims data from hospitals with diagnostic data (e.g., laboratory data and diagnostic imaging reports) at the patient level. Using diagnostic data as the gold standard for disease identification, researchers can validate and refine their claims-based identification algorithms. Diagnostic data are collected as needed for each validation study, and data are linked using pseudonymized medical record numbers. Personal information is protected through the use of research identification numbers. To demonstrate the platform's feasibility, we collected data on respiratory syncytial virus (RSV) infections and intussusception cases. Eight hospitals have agreed to participate in the CLEAR Study, and three have completed claims data provision. We obtained data for 5,022 RSV infection cases with 25,920 diagnostic tests, and 1,450 intussusception cases with 561,984 diagnostic tests. We also analyzed the initial diagnostic data for 39,212 RSV infection cases and 439,088 intussusception cases, demonstrating that the database can be used to validate algorithms for these diseases. The CLEAR Study is a newly developed database platform in Japan that facilitates validation studies of claims data for various diseases. By promoting validation studies, this platform will help to improve the reliability of claims-based epidemiological studies and drug risk assessments in Japan.

Background: Changes in nutritional status during the coronavirus disease 2019 (COVID-19) pandemic may be attributed to the obesity-causing environment that had existed before. This paper aimed to investigate trends in thinness, overweight, and obesity among Chinese children aged 2 to 18 years from 2010 to 2020 and assess the potential influence of pandemic.

Methods: The Chinese Family Panel Studies that were conducted every 2 years between 2010 and 2020 included 48,642 children between the ages of 2 and 18 years. Height and mass were reported, and the body mass index (BMI) was calculated. The prevalence of thinness, overweight, and obesity was estimated using sex- and age-specific BMI cut-offs adopted by the International Obesity Task Force and population-weighted procedures. Linear regressions were used to estimate trends.

Results: The prevalence of thinness decreased from 25.5% to 22.2% but increased among children aged 2 to 6 years. The prevalence of overweight and obesity decreased from 24.6% and 14.2% to 22.5% and 10.0%, respectively. However, these decreases in the prevalence of overweight and obesity were attributed mostly to children aged 2 to 6 years, and the prevalence increased slightly among children aged 13 to 18 years. The prevalence of obesity in 2020 among only boys aged 13 to 15 years was greater than the estimated projections using data from 2010 to 2018.

Conclusion: From 2010 to 2020, the prevalence of all forms of malnutrition among Chinese children decreased, with age disparities. During the pandemic, overweight became more common among pubertal boys. Future interventions as well as policies ought to give high-risk groups priority.

Background: This study aimed to describe the clinical outcomes and medical costs of hospitalized children requiring daily medical care (CRDMC), a patient group for which government-led support has developed rapidly in Japan.

Methods: A retrospective longitudinal study was conducted using a nationwide administrative database. All hospitalizations of children aged under 18 years discharged from April 2014 to March 2021 were included. Clinical outcomes and medical costs were compared between CRDMC and non-CRDMC hospitalizations. The estimated increase in the proportion of CRDMC medical costs among all pediatric hospitalizations during the study period was also calculated.

Results: Among the 1,531,456 hospitalizations included, 91,413 were identified as CRDMC. CRDMC accounted for 3.7% of the annual unique inpatients. The 30-day readmission rate among CRDMC was 27.5%, and the rate among those receiving multiple types of medical care was higher at 33.7%. The inpatient medical cost of CRDMC accounted for 20.3% of pediatric inpatient medical costs, with an estimated rise of 1.2881 (95% confidence interval, 1.2110-1.3702) during the study period. In the breakdown of the medical costs, the proportion of injection drug fees increased most rapidly.

Conclusion: The high 30-day readmission rate in CRDMC was distinctive among the clinical outcomes. The proportion of medical costs for CRDMC in pediatric inpatients was high, although CRDMC accounted for only a small proportion of annual unique inpatients. Further support for CRDMC must be based on the unique characteristics of this population.