Background: The mechanistic associations between obesity and risk of colorectal cancer (CRC) remain unclear. Here, using body mass index (BMI) as an obesity indicator, we decomposed the total effects of obesity on the risk of CRC into: (1) direct effects, which are possibly mediated by unmeasured or currently unknown factors; (2) indirect effects mediated by circulating leptin and adiponectin; and (3) indirect effects that are not mediated by circulating leptin and adiponectin but by hyperinsulinemia and chronic inflammation (assessed via circulating connecting peptide and C-reactive protein, respectively).

Methods: We adopted a causal mediation framework, using data from a large prospective cohort study of 44,271 Japanese men.

Results: BMI was not associated with the risk of CRC due to direct and indirect effects that were not mediated by circulating leptin and adiponectin. By contrast, individuals with BMIs of 25.0–27.4 kg/m² (risk ratio 1.29; 95% confidence interval, 0.98–1.69) and ≥27.5 kg/m² (risk ratio 1.28; 95% confidence interval, 0.98–1.68) had a higher risk of CRC due to indirect effects of circulating leptin and adiponectin.

Conclusion: Our mediation analyses suggest that the association between BMI and CRC risk may be largely mediated by a pathway involving circulating leptin and adiponectin.

Background: Disasters such as earthquakes, terrorism, and pandemics have triggered post-traumatic stress disorder (PTSD), and discrimination against the affected individuals has been linked to the development of PTSD. However, there is limited evidence regarding the association between discrimination against coronavirus disease 2019 (COVID-19) patients and probable PTSD in Japan.

Methods: We conducted a cross-sectional study utilizing a web-based questionnaire targeting individuals who had contracted the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) infection in Sapporo City. A total of 4,247 individuals with laboratory-confirmed SARS-CoV-2 infection spanning from February 2020 to February 2022 completed the questionnaire (response rate: 15.9%). Probable PTSD was measured using the three-item Posttraumatic Diagnostic Scale. The stratified exact logistic regression was applied to calculate the odds ratios (ORs) of probable PTSD for COVID-19-related discrimination with adjusted factors.

Results: This study included 3,626 patients who had a history of SARS-CoV-2 infection. Among them, 321 patients (8.9%) experienced COVID-19-related discrimination. The prevalence of probable PTSD was 19.6% (63/321) among the patients who experienced COVID-19-related discrimination, and 4.6% (152/3,305) among those who had not encountered such discrimination. The adjusted OR of COVID-19-related discrimination for probable PTSD was 4.68 (95% confidence interval [CI], 3.36–6.53). The population attributable fraction of probable PTSD attributable to COVID-19-related discrimination among COVID-19 patients was estimated to be 23.4% (95% CI, 21.5–25.3%).

Conclusion: The comprehensive epidemiological survey of COVID-19 patients in Japan showed that COVID-19-related discrimination was associated with a higher prevalence of probable PTSD. Mitigating discrimination could be helpful to attenuate PTSD in future pandemics.

Background: No previous study reported an association of paternal involvement in childcare and housework with maternal physical punishment.

Methods: Using data from the Japanese Longitudinal Survey of Newborns in the 21st century (N = 38,554), we analyzed responses about fathers’ involvement in childcare and housework at 6 months and mothers’ spanking of children at 3.5 years. Fathers’ involvement in childcare and housework was scored and categorized into quartiles. Spanking frequency was asked in the “often”, “sometimes”, or “not at all” categories. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the mothers’ often spanking children were computed for the fathers’ involvement in childcare and housework. We also stratified the association by fathers’ working hours (40–49, 50–59, or ≥60 hours/week).

Results: Among the 16,373 respondents, the proportion of mothers who often spanked their children was 4.8%. Compared with the lowest quartile, a higher frequency of paternal involvement in housework was associated with a lower risk of spanking children (P_trend = 0.001). Adjustment for covariates attenuated the association, but significant association was observed in the 3^rd quartile of paternal involvement in housework (OR 0.77; 95% CI, 0.62–0.96). When the fathers worked fewer than 50 hours a week, a significant negative association was observed between the fathers’ frequency of childcare and the likeliness of the mothers’ spanking their children (P_trend = 0.02).

Conclusion: The fathers’ active involvement in childcare and housework could reduce the mothers’ physical punishment for their children.

Background: In high-income countries, socioeconomically disadvantaged adolescents experience a higher risk of obesity, which may have been further exacerbated during the early phase of the coronavirus disease 2019 (COVID-19) pandemic. This study aimed to investigate the association between obesity and familial financial insecurity, utilizing data on subjective household socioeconomic status (SES) and perceived family-level financial deterioration induced by COVID-19.

Methods: We utilized data from the Korea Youth Risk Behavior Survey, a nationally representative sample of Korean adolescents, in 2020 and 2021. The independent and joint associations of two primary exposures, subjective household SES and perceived family-level financial deterioration, with obesity were assessed using multivariable logistic regression models.

Results: Among 106,979 adolescents aged 12–18 years, 16.9% of boys and 9.0% of girls met the criteria for obesity. Notably, 70.5% reported experiencing COVID-19-related financial deterioration. Both subjective household SES and perceived family-level financial deterioration independently and synergistically increased the odds of obesity. A graded association was observed between obesity and lower SES and more severe financial deterioration, particularly among girls. Younger adolescents were more sensitive to household SES, whereas older adolescents were more sensitive to financial deterioration.

Conclusion: While the COVID-19 pandemic presented a unique social context, our findings highlight that financially insecure adolescents were at an increased risk of obesity during the early phase of the pandemic. This underscores the need for obesity-prevention strategies in times of macroeconomic recession to address not only the persistent influence of household SES but also the direct and indirect effects of family-level financial deterioration.

Background: Despite the fact that competing risks are inevitable in epidemiological and clinical studies, distinctions between the hazard ratio estimated by handling competing risks as censoring and the subditribution hazard ratio are often overlooked.

Methods: We derived quantitative relationships between subdistribution hazard ratio and cause-specific hazard ratio and derive an approximate calculation method to transform the two into each other. Numerical examinations of hypothetical six scenarios and published information of a randomized clinical trial of cholesterol-lowering therapy and a registry of acute myeloid leukemia were provided.

Results: General and approximate relationships under rare event assumptions between the two types of hazard ratio were given. The approximation formula is based on a survival ratio and has two possible applications. First, one can calculate a subdistribution hazard ratio from published information. Second, this formula allows sample size estimation that takes the presence of competing risks into account.

Conclusion: The distinction between the two types of hazard ratio can be addressed by focusing on two quantities. One is how the event of interest and competing risk is rare, and the other is the survival ratio.

Background: The use of life-sustaining treatment (LST) in the final stage of life is a major policy concern due to increased costs, while its intensity does not correlate with quality. Previous reports have shown declining trends in LST use in Japan. However, regional practice variations remain unclear. This study aims to describe regional variations in LST use before death among the oldest old in Japan.

Methods: A descriptive study was conducted among patients aged 85 years or older who passed away between April 2013 and March 2014. The study utilized health insurance claims from Japan’s National Database (NDB) to examine the use of cardiopulmonary resuscitation (CPR), mechanical ventilation (MV), and admission to the acute care ward (ACW) in the last 7 days of life.

Results: Among 224,391 patients, the proportion of patients receiving LST varied by region. CPR ranged from 8.6% (Chubu) to 12.9% (Shikoku), MV ranged from 7.1% (Chubu) to 12.3% (Shikoku), and admission to ACW ranged from 4.5% (Chubu) to 10.1% (Kyushu-Okinawa). The adjusted odds ratios (AOR) for regional variation compared with Kanto were as follows: CPR (in Shikoku, AOR 1.85; 95% confidence interval [CI], 1.73–1.98), MV (in Shikoku, AOR 1.75; 95% CI, 1.63–1.87), and ACW admission (in Kyushu-Okinawa, AOR 1.69; 95% CI, 1.52–1.88).

Conclusion: The study presents descriptive information regarding regional differences in the utilization of LST for the oldest old in Japan. Further research is necessary to identify the factors that contribute to these variations and to address the challenge of improving the quality of end-of-life care.