Background: An association between birth weight and cardiovascular disease (CVD) in adulthood has been observed in many countries; however, only a few studies have been conducted in Asian populations.

Methods: We used data from the baseline survey (2011–2016) of the Japan Public Health Center-based Prospective Study for the Next Generation Cohort, which included 114,105 participants aged 40–74 years. Adjusted prevalence ratios (aPRs) and 95% confidence intervals (CIs) were calculated from the prevalence of present and past histories of CVD and other lifestyle-related diseases, including hypertension, diabetes, hyperlipidemia, and gout, by birth weight, using Poisson regression.

Results: The prevalence of CVD increased with lower birth weight, with the highest prevalence among those with birth weight under 1,500 grams (males 4.6%; females 1.7%) and the lowest one among those with birth weight at or over 4,000 g (males 3.7%: females 0.8%). Among 88,653 participants (41,156 males and 47,497 females) with complete data on possible confounders, birth weight under 1,500 g was associated with a higher prevalence of CVD (aPR 1.76; 95% CI, 1.37–2.26), hypertension (aPR 1.29; 95% CI, 1.17–1.42), and diabetes (aPR 1.53; 95% CI, 1.26–1.86) when a birth weight of 3,000–3,999 grams was used as the reference. Weaker associations were observed for birth weight of 1,500–2,499 grams and 2,500–2,999 grams, while no significant associations were observed for birth weight at or over 4,000 grams. The association between birth weight and the prevalence of hyperlipidemia was less profound, and no significant association was observed between birth weight and gout.

Conclusion: Lower birth weight was associated with a higher prevalence of CVD, hypertension, and diabetes in the Japanese population.

Background: We prospectively examined the associations of total fat and fatty acid intake with type 2 diabetes (T2D) among Japanese adults.

Methods: This study was conducted using data from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC). A validated food frequency questionnaire evaluated the intake of total fat and fatty acids. Diabetes was assessed using self-reported data. Multivariable logistic regression analysis was performed to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of incident T2D across quintiles of total fat and fatty acid intake after adjusting for potential confounders.

Results: A total of 19,088 non-diabetic participants (age range, 40–79 years) enrolled in the JACC between 1988 and 1990 were included in this study. During the 5-year study period, 494 the participants developed T2D. The OR of T2D for the highest versus lowest quintiles was 0.58 (95% CI, 0.37–0.90) for total fat, 0.78 (95% CI, 0.51–1.20) for saturated fatty acid (SFA), 0.55 (95% CI, 0.35–0.86) for monounsaturated fatty acids (MUFA), 0.61 (95% CI, 0.39–0.96) for polyunsaturated fatty acids (PUFA), 0.64 (95% CI, 0.42–0.99) for n-3 PUFA, and 0.70 (95% CI, 0.45–1.09) for n-6 PUFA. Total fat and fatty acid (except SFA and n-6 PUFA) intake were inversely associated with T2D in men. Total fat and fatty acid intake were not associated with T2D in women.

Conclusion: Higher intakes of total fats, MUFA, PUFA, and n-3 PUFA were inversely associated with T2D among Japanese men.

Background: In regions with a high prevalence of peanut allergy (PA), there is a consensus that the introduction of peanuts in early infancy is preventive against the development of PA. However, few studies have investigated whether the introduction of peanuts to infants is associated with PA in regions with a low prevalence of PA, including Japan.

Methods: We used data from 74,240 mother–child pairs who participated in the Japan Environment and Children’s Study, a prospective birth cohort recruited between January 2011 and March 2014. A logistic regression model was used to analyze the association between infantile peanut introduction and PA at the age of 4 years with non-infantile peanut introduction as the reference group, adjusted for potential confounders.

Results: The percentage of infantile peanut introduction was 4.9% (n = 3,294), and 286 (0.4%) participants had allergic symptoms to peanuts at 4 years of age. Of all participants, 129 (0.2%) had PA at 4 years of age, which was defined as allergic symptoms and sensitization to peanuts. Those with infantile peanut introduction had a lower prevalence of PA than those without infantile peanut introduction, although this did not reach statistical significance (adjusted odds ratio 0.53; 95% confidence interval, 0.17–1.68). Sensitivity analysis using IgE-mediated symptoms caused by peanuts as the outcome showed a similar result in relation to infantile peanut introduction.

Conclusion: In countries with a low prevalence of PA, the effect of infantile peanut introduction on PA prevention was unclear.

Background: Studies on the association between preserved ratio impaired spirometry (PRISm) and dementia are limited. Indeed, PRISm has often been overlooked or ignored as an index of lung function impairment. Therefore, we investigated the association of PRISm with the risk for the development of dementia in an older Japanese population.

Methods: A total of 1,202 community-dwelling, older Japanese participants aged ≥65 years without dementia were followed up for a median of 5.0 years. Participants were categorized by spirometry as follows: normal spirometry (FEV₁/FVC ≥0.70 and FEV₁ ≥80% predicted), PRISm (≥0.70 and <80%), airflow limitation (AFL) Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 (<0.70 and ≥80%), and AFL GOLD 2 to 4 (<0.70 and <80%). Hazard ratios (HRs) and their 95% confidence intervals (CIs) were computed using a Cox proportional hazards model.

Results: During the follow-up period, 122 participants developed dementia. The age- and sex-adjusted incidences of dementia in the participants with normal spirometry, PRISm, AFL GOLD 1, and AFL GOLD 2 to 4 were 20.5, 37.0, 18.4, and 28.6 per 1,000 person-years, respectively. Participants with PRISm had a higher risk of dementia (HR 2.04; 95% CI, 1.19–3.49) than those with normal spirometry after adjusting for confounders. Moreover, both reduced FEV₁% predicted values and FVC% predicted values were associated with the risk of dementia.

Conclusion: PRISm was associated with an increased risk of dementia in a general older Japanese population.

Background: Currently, awareness about platelet count (PC) and its consequences for perinatal outcome have increased, but there is little reliable evidence on fecundability.

Methods: Based on the National Free Pre-conception Check-up Projects supported by the Chinese government, 5,524,886 couples met the inclusion criteria and were included in this cohort study. Cox regression models were adopted to estimate fecundability ratios (FRs) and their 95% confidence intervals (CIs) for pre-pregnancy PC quintiles. Restricted cubic splines were used to flexibly model and visualize the relationship of PC with FRs. Microsoft SQL server and R software were used for data management and analysis.

Results: The median of pre-pregnancy PC among women was 221.00 × 10⁹/L. The first (<177.00 × 10⁹/L) and second quintile (177.00–207.99 × 10⁹/L) of PC showed slightly increased fecundability (Q1: adjusted FR 1.05; 95% CI, 1.04–1.06; Q2: adjusted FR 1.04; 95% CI, 1.03–1.05), while higher quintals (Q4: 236.00–271.99 × 10⁹/L; Q5: ≥272.00 × 10⁹/L) were related to reduction of fecundability, when compared with the third quintile of PC (208.00–235.99 × 10⁹/L) (Q4: adjusted FR 0.96; 95% CI, 0.95–0.97; Q5: adjusted FR 0.88; 95% CI, 0.87–0.89). In the first quintiles (<177.00 × 10⁹/L), only 20.93% women had PC below 129.94 × 10⁹/L. An inverse-U-shaped association was consistently observed among women such that the lower PC within the normal range (<118.03 × 10⁹/L) and higher PC (>223.06 × 10⁹/L) were associated with the risk of reduced female fecundability (P for non-linearity < 0.01).

Conclusion: PC is associated with female fecundability. Further classification of PC levels may deepen our understanding of the early warnings and significance of female fecundability.

Background: The novel coronavirus disease 2019 (COVID-19) pandemic has significantly impacted end-of-life decisions for cancer patients in Japan, with disparities existing between preferred and actual care settings. Our study investigates the potential shifts in cancer death locations during the pandemic and if there were excess cancer deaths.

Methods: Utilizing national mortality data from the Ministry of Health, Labour and Welfare from January 2012 to February 2023, we identified cancer deaths using International Classification of Disease, 10^th revision codes. We assessed death locations, including medical institutions, nursing facilities, and homes. The Farrington algorithm was employed to estimate expected death counts, and the differences between observed and expected counts were denoted as excess deaths.

Results: From January 2018 to February 2023, there was consistently increase in the weekly observed cancer deaths. The presence of a definitive excess during the pandemic period remains uncertain. The percentage of deaths in medical institutions declined from 83.3% to 70.1%, while home deaths increased from 12.1% to 22.9%. Between April 2020 and February 2023, deaths in medical institutions frequently fell below the 95% prediction lower limit. Home deaths consistently exceeded the 95% prediction upper limit, with significant excess deaths reported annually.

Conclusion: Our study found a shift in cancer death locations from medical institutions to homes in Japan during the COVID-19 pandemic. Our study did not confirm an overall increase in cancer deaths during this period. As with global trends, the profound shift from hospitals to homes in Japan calls for a comprehensive exploration to grasp the pandemic’s multifaceted impact on end-of-life cancer care decisions.

Background: The coronavirus disease 2019 (COVID-19) pandemic has affected cancer care. The aim of this study was to clarify the trend of colorectal cancer (CRC) stage distribution in Japan during the COVID-19 pandemic.

Methods: In this retrospective study, we used an inpatient medical claims database established at approximately 400 acute care hospitals. From the database, we searched patients who were identified as having the main disease (using International Classification of Diseases, 10^th revision codes [C18.0–C20]) between January 2018 and December 2020. A multivariate logistic regression analysis was used to determine the impact of the pandemic on CRC stage distribution each month, and the odds ratio (OR) for late-stage cancer was calculated.

Results: We analyzed 99,992 CRC patients. Logistic regression analysis, including the interaction term between increased late-stage CRC effect during the pandemic period and by each individual month, showed that the OR for late-stage CRC was highest in July during the pandemic, at 1.31 (95% confidence interval [CI], 1.13–1.52) and also significantly higher in September at 1.16 (95% CI, 1.00–1.35).

Conclusion: We investigated the trend of CRC stage distribution during the COVID-19 pandemic using a nationwide hospital-claims database in Japan and found that the proportion of early-stage cancers tended to decrease temporarily after the state of emergency declaration due to the COVID-19 pandemic, but the effect was only temporary.