Background: We aimed to explore behavioral and environmental factors associated with carbon monoxide (CO) poisoning from waterpipe smoking.

Methods: We searched the MEDLINE, Web of Science, PubMed, CINAHL, Ichushi-Web, and CiNii databases for case reports or case series on acute CO poisoning and polycythemia related to waterpipe smoking, up to February 2025. Article selection and data extraction were performed with the assistance of generative artificial intelligence (AI) using predefined criteria. All processes performed by AI were verified by the author through careful article review.

Results: A total of 68 cases of acute CO poisoning and 13 cases of polycythemia were identified from 37 case reports and series. Most cases involved individuals aged 20‒29 years. The most common symptoms of acute CO poisoning following waterpipe smoking were syncope, headache, dizziness, and nausea/vomiting, in that order. Symptoms typically occurred shortly after exposure, followed by during exposure, and delayed after exposure. Acute CO poisoning was observed after as little as one hour of waterpipe smoking, in outdoor settings, and from secondhand waterpipe smoking exposure.

Conclusions: Both active and passive waterpipe smoking can cause acute CO poisoning, depending on the intensity, duration, and environment of exposure. Symptoms may arise not only during or immediately after smoking but also with a delayed onset. The implementation of environmental regulations for closed establishments is necessary to prevent mass CO poisoning and protect workers from it. Further research is needed to better understand the behavioral and environmental factors contributing to CO poisoning from waterpipe smoking.

Introduction: Japan, the world's third-largest pharmaceutical market, introduced new guidelines in 2019 to address ethical concerns in pharmaceutical company-physician relationships. This study aimed to analyze Japanese physicians' attitudes toward these strengthened regulations.

Methods: An online survey of 1,203 Japanese physicians was conducted in November 2019. Respondents were categorized based on their frequency of interaction with pharmaceutical companies: frequent (82, 6.8%), moderate (930, 77.3%), or rare (191, 15.9%). The survey assessed awareness of the new guidelines, perceived changes in promotional activities, and attitudes toward stricter regulations. Multivariable modified Poisson regression was used to identify factors associated with opposition to the regulations.

Results: A total of 640 (53.3%) respondents opposed stricter regulations, while 325 (27.1%) were in favor. Physicians with frequent (adjusted Incidence Rate Ratio [aIRR] 1.61, 95% confidence interval [CI] 1.24-2.10) or moderate (aIRR 1.53, 95% CI 1.24-1.89) interactions were more likely to oppose regulations compared with those with rare interactions. Hospital directors/managers, those affiliated with private institutions, and recent graduates also showed higher opposition. The main reason for favoring regulations was to promote healthy industry relationships (38, 9.3%), while the primary concern among those opposed was related to information gathering or potential patient disadvantages (88, 21.6%).

Conclusions: The study reveals diverse views on industry-physician relations in Japan. Frequent interactions and leadership roles correlate with opposition to stricter regulations. The results suggest a need for balanced policies that consider varied perspectives.

Introduction: No comprehensive national profiles of oral squamous cell carcinoma (OSCC) have been established in Japan. We set out to describe the profiles of OSCC cases, including demographic characteristics, regional disparities, and survival time on a national basis, using a population-based dataset in Japan.

Methods: Using the national cancer registry (NCR) of Japan, we aggregated data on cases of OSCC from 2016 to 2019 that were classified according to the diagnostic criteria specified in the Japanese oral cancer guidelines. We calculated annual, detailed site-specific distributions by sex and age-standardized incidence rates for each year. The standardized incidence ratios by prefecture were computed using 2016 to 2019 data. One-year overall survival was estimated using the Kaplan-Meier method. Univariate and multivariate analyses were conducted using the Cox proportional hazards model.

Results: Between 2016 and 2019, data were obtained on 30,537 OSCC incidence cases. In the most recent year, 2019, 57.0% of patients were men, and the mean age was 70.3 years. Among the specific OSCC sites, the tongue was the most common, accounting for more than half the cases. Over half the cancers were localized at the time of diagnosis. The age-standardized incidence rate in 2019 was 5.12 per 100,000 population. The standardized incidence ratios of OSCC among different prefectures ranged from 0.77 (Gifu Prefecture) to 1.37 (Miyagi Prefecture). The one-year survival rate for all OSCC cases diagnosed between 2016 and 2019 was 83.5%. Cox proportional hazards model analysis, adjusted for all covariates, revealed that women had a significantly lower risk of death within one year than men (hazard ratio = 0.81, 95% confidence interval = 0.76-0.87).

Conclusions: Our study provides an overview of OSCC epidemiology in Japan using the NCR population-based dataset.

Introduction: Suicide remains a major public health issue in Japan, where the suicide mortality rate is high across all age groups. While existing national statistics provide limited insight into the individual backgrounds of those who die by suicide, detailed forensic data offer an opportunity to explore the characteristics associated with different methods of suicide.

Methods: We conducted a retrospective study using anonymized data extracted from police documents submitted to the Osaka Medical Examiner's Office for medicolegal investigation. Among 1,129 individuals who died by suicide in 2017 and 2019, 669 cases with complete data were analyzed. Latent class analysis (LCA) was used to classify individuals based on variables, including suicide method, age group, sex, occupation, psychiatric consultation history, suicide attempt history, and living arrangement.

Results: Latent class analysis identified three distinct classes. Class 1 (38.1%) consisted mainly of middle-aged unemployed females with a history of psychiatric consultation, living with others, and frequently jumping from heights. Class 2 (35.1%) was characterized by elderly unemployed males with no history of psychiatric consultation and no suicide attempt history, predominantly using hanging. Class 3 (26.8%) comprised younger employed males with no history of psychiatric consultation and no suicide attempt history, also showing a high proportion of hanging and jumping from heights, and poisoning.

Conclusions: The use of LCA revealed distinct subgroups of suicide deaths characterized by background factors and method choice. These findings may aid in identifying vulnerable populations and inform the development of targeted suicide prevention strategies in Japan. More broadly, our results highlight the value of combining medicolegal information with data-driven classification methods to better understand suicide in other settings.

Introduction: Despite mounting recognition of the importance of student engagement in curriculum development, the current status of student engagement from medical trainees' perspectives has yet to be elucidated. Particularly in Japan, where the educational system places strong emphasis on teacher authority, it is possible that medical student engagement is not promoted as effectively as it could be, and that engagement is not fully perceived by medical students. Thus, we aimed to elucidate the current status of student engagement in curriculum development from the perspective of medical trainees, and to explore factors associated with medical trainees' perceptions of student engagement.

Methods: We performed a nationwide cross-sectional study in Japan from April to May 2025. Participants were newly entered medical residents who took the General Medicine In-Training Examination postgraduate "Year-0." They completed an anonymous online self-administered questionnaire. We analyzed the closed-ended questions using descriptive statistics and linear mixed-effects models, and applied inductive content analysis to the open-ended questions.

Results: Of 748 examinees, 428 (57.2%) were included in the analysis. A total of 105 (24.5%) did not perceive that there were student engagement initiatives at their medical school. Only 38 (8.9%) reported participation. The trainees' overall perceptions of how well their opinions were reflected in the medical curriculum were moderate, with a mean score of 5.41 out of 10. This result was supported by the content analysis findings, which identified four themes, including "desire to see more of medical students' opinions reflected" and "disappointment that medical students' opinions are not reflected." Multilevel analysis demonstrated that females had significantly more favorable perceptions than males.

Conclusions: Our findings indicated that awareness, implementation, and perceived value of student engagement remain limited from the perspectives of medical trainees in Japan. Medical educators should implement structural and cultural reforms and develop effective strategies tailored to diverse institutional environments.

Introduction: The European Working Group on Sarcopenia in Older People 2 revised its diagnostic criteria for sarcopenia, highlighting the importance of evaluating not only skeletal muscle mass but also muscle quality. Recently, the extracellular water-to-total body water ratio (ECW/TBW) has gained attention as an indicator of muscle quality. The aim of this study was to investigate the sex differences in the effect of aging on ECW/TBW in community-dwelling individuals.

Methods: This cross-sectional study was conducted among community-dwelling males and females (aged ≥20 years). A total of 824 participants (345 males, 479 females) were included. ECW/TBW was measured using bioelectrical impedance analysis. Associations between age and ECW/TBW were analyzed separately for males and females using Spearman's correlation coefficient. Participants were categorized into three age groups: 20-39 years, 40-64 years, and ≥65 years. Among males (n = 345), the age groups 20-39, 40-64, and ≥ 65 years comprised 124, 128, and 93 participants, respectively. Among females (n = 479), the corresponding numbers were 94, 164, and 221 participants, respectively. The Kruskal-Wallis test was used to compare ECW/TBW among the three groups for both males and females. Bonferroni's post hoc test was used to determine the significance when the main effect was confirmed in the Kruskal-Wallis test. In addition, a two-way analysis of variance was performed on ECW/TBW with age group and sex as factors.

Results: Correlation analyses revealed a significant positive association between age and ECW/TBW in both males (ρ = 0.733, p < 0.001) and females (ρ = 0.684, p < 0.001). For both males and females, a main effect of age on ECW/TBW was observed among the three groups. In addition, for both males and females, the ECW/TBW in the ≥65-year group was significantly higher than in the 20-39 and 40-64-year groups. ECW/TBW showed a significant interaction between age group and sex (p < 0.001).

Conclusions: The results of this study indicated that age is positively related to ECW/TBW in community-dwelling males and females. Additionally, the influence of aging on ECW/TBW was more pronounced in males than in females. Based on our findings, assessing ECW/TBW is important for capturing age-related changes.

Introduction: Workplace social capital (WSC), defined as the features of social organization that promote coordination and cooperation for mutual benefit, is a relevant construct that contributes positively to employee and organizational wellness, and has recently attracted wide attention. However, factors associated with WSC in the field of medical education have not been investigated, including regarding the effect of physician working hour restrictions. Thus, the aim of the study was to investigate differences in the WSC of resident physicians before and after the April 2024 introduction of restrictions on physician working hours in Japan.

Methods: We conducted a nationwide repeated cross-sectional survey in 25 hospitals across Japan. Pre- and post-restriction data were obtained in July and August 2022 and in December 2024, respectively. We evaluated WSC using the Japanese medical resident version of the WSC Scale, which comprises horizontal trust (i.e., trust in co-workers) and vertical trust (i.e., trust in supervisors) subscales. We used the total score and its domain scores, all of which range from 1 to 5, with higher scores indicating greater WSC, as outcome variables. We created a dummy variable (1 = post-restriction data [December 2024], 0 = pre-restriction data [July-August 2022]) and used it as the explanatory variable. We used a linear mixed-effects model to adjust clustering within hospitals and individual covariates.

Results: We analyzed data for 428 respondents (pre-restriction, 246; post-restriction, 182 participants; man, 272). After adjusting possible confounders and clustering within hospitals, physician working hour restrictions were significantly associated with greater vertical trust (adjusted mean difference, 0.17; 95% confidence interval, 0.02 to 0.32). No clear trend was observed in the association among restrictions, total WSC score (adjusted mean difference, 0.13; 95% confidence interval, −0.01 to 0.26), and horizontal trust score (adjusted mean difference, 0.10; 95% confidence interval, −0.05 to 0.24).

Conclusions: This nationwide multicenter study revealed significant vertical trust score differences between pre- and post-physician working hour restrictions. The implementation of physician working hour restrictions has improved vertical trust. These findings contribute to the literature on potential benefits of working hour restrictions on the organization of physician life and enhancement of patient care quality.

Introduction: Poor appetite is a prevalent and serious problem among older adults. However, real-world data regarding appetite and nutrient intake among community-dwelling older adults are scarce. The aim of this study was to clarify the association between appetite and nutrient intake status among community-dwelling older adults.

Methods: This cross-sectional study involved participants (N = 583) from the cohort of the "Otassha study," conducted among community-dwelling older adults. Appetite was assessed using the Japanese version of the Simplified Nutritional Appetite Questionnaire. Nutrient intake was calculated using the Brief-Type Self-Administered Diet History Questionnaire. In addition, compliance status was assessed using the recommended dietary allowance (RDA) of various nutrients based on the "Dietary Reference Intakes for Japanese (2020)." The association between compliance status and appetite was analyzed using logistic regression, with the RDA of multiple nutrients as the dependent variable and poor appetite as the independent variable.

Results: In the study population, 32.1% of participants had poor appetite. Multivariable logistic regression revealed that poor appetite was significantly associated with insufficient vitamin C intake relative to the RDA (odds ratio 1.67; 95% confidence interval 1.08-2.57).

Conclusions: This study demonstrated an association between poor appetite and vitamin C intake among community-dwelling older adults.

Introduction: Chronic obstructive pulmonary disease (COPD) is a complex, multi-component disorder characterized by a long-lasting, irreversible airflow limitation due to inflammation, which leads to narrowing of the airway lumen. A variety of influencing factors may cause cognitive impairment (CI) in patients with COPD, including age, disease duration, severity, hypercapnia, smoking, and vascular dysfunction. This study assessed cognitive functions in non-hypoxic stable COPD patients.

Methods: An observational study was conducted in the Department of Physiology and Medicine, Rajasthan University of Health Sciences College of Medical Sciences (RUHS CMS). A total of 120 subjects were recruited. The cases (group A) were selected according to the Global Initiative for Obstructive Lung Disease (GOLD) classification. GOLD stage 1 and 2 patients confirmed by spirometry. Controls (group B) were selected as age-matched healthy volunteers(HVs) from the society. The Mini-Mental State Examination (MMSE) and event-related potential (P300) were used to assess cognitive functions in both groups. Data was analyzed using appropriate tests, and p < 0.05 was considered significant.

Results: The mean MMSE score was found to decrease in Group A compared to Group B. The mean MMSE score in group A was 24.65 with an standard deviation of ± 2.05; in group B, it was detected as 27.56 ± 2.15 (p < 0.00001). The mean latency of the P300 wave was prolonged in some cases, and a decrease in the Amplitude of the P300 wave was observed in some cases compared to the control group. Mean latency in case group 298.48 ± 21.98 milliseconds compared to control group 265.89 ± 15.80 milliseconds, with a significant p-value <0.0001. The mean amplitude in group A was detected as 4.25 ± 1.502 μV, compared to a mean of 6.06 ± 1.94 μV in group B.

Conclusion: Patients with COPD have a higher risk of CI compared to the age-matched healthy volunteer group.

Introduction: The expansion of genetic medicine in Japan has created an urgent need for regionally-adaptable systems to ensure equitable implementation. This study examines challenges in developing a sustainable framework for regional genetic medicine, using Shizuoka Prefecture-a non-metropolitan area with average socioeconomic indicators-as a case model.

Methods: A two-phase survey was conducted between December 2023 and January 2024. The first phase involved a questionnaire sent to 44 major medical institutions and all board-certified clinical genetics specialists in the prefecture. In the second phase, 20 of the responding institutions completed a more detailed follow-up survey. The surveys assessed human resource capacity, institutional collaboration, and the adoption of digital infrastructure.

Results: The results revealed critical shortages in clinical geneticists, certified genetic counselors, and genetic nursing specialists. Inter-institutional collaboration was limited, with few systems in place for data sharing or regional coordination. Digital tools, such as remote consultation systems and information platforms, were underutilized. Respondents identified the need for shared infrastructure, better communication among institutions, and flexible strategies to address geographic and systemic barriers.

Conclusions: This study highlights the urgent need for network-based infrastructure and a specialized workforce to support the expansion of genetic medicine in regional settings. The findings from Shizuoka are likely reflective of broader national challenges and underscore the importance of policy and system-level interventions to promote equitable access to genetic healthcare across Japan.

Introduction: Time elapsed since trauma onset is a critical determinant of prognosis in trauma patients. However, factors behind prolonged prehospital on-site time remain unclear. This study aimed to identify associated factors in trauma cases.

Methods: Using a nationwide Japanese database, adults who experienced trauma and were treated between January 2004 and May 2019 were identified. Multivariable logistic regression with multiple imputations for missing data was performed to compare characteristics of patients with shorter and longer prehospital on-site times.

Results: Data from 150,215 patients were included. Multivariable logistic regression with multiple imputations for missing data revealed that longer prehospital on-site time was associated with younger age, male sex (odds ratio [OR] 1.14; 95% confidence interval [CI] 1.11-1.16), weekends and holidays (OR, 1.06; 95% CI, 1.03-1.08), alcohol consumption (OR, 1.31; 95% CI, 1.26-1.36), fall (OR, 1.07; 95% CI, 1.05-1.10), other blunt trauma (OR, 1.12; 95% CI, 1.07-1.18), suicide (OR, 1.20; 95% CI, 1.13-1.27), violence (OR, 1.33; 95% CI, 1.20-1.46), hypotension (OR, 1.15; 95% CI, 1.09-1.22), higher Revised Trauma Score (OR, 1.21; 95% CI, 1.20-1.23), Abbreviated Injury Scale (AIS) category 6 (spine) ≥ 3 (OR, 1.21; 95% CI, 1.17-1.25), AIS category 7 (upper extremities) ≥ 3 (OR, 1.15; 95% CI, 1.10-1.21), immobilization (OR, 1.25; 95% CI, 1.22-1.28), intravenous line placement (OR, 1.27; 95% CI, 1.17-1.37), intubation (OR, 1.44; 95% CI, 1.26-1.64), mental disease (OR, 1.07; 95% CI, 1.02-1.13), chronic kidney disease undergoing hemodialysis (OR, 1.12; 95% CI, 1.03-1.22), and malignancy (OR, 1.11; 95% CI, 1.04-1.18).

Conclusions: Several factors associated with prolonged prehospital on-site time were identified. Interventions targeting these factors may help shorten prehospital on-site time.

Introduction: Children with severe motor and intellectual disabilities (SMIDs) require complex care involving both technical skill and emotional presence. Pediatric residents often lack meaningful exposure to such patients, and little is known about how they make sense of these learning experiences.

Methods: We conducted a qualitative study using an interpretative phenomenological analysis to explore how pediatric residents experienced a three-month rotation at a facility for children with SMID in Japan. Four residents were interviewed twice during their rotations. Interviews were transcribed verbatim and analyzed through iterative coding and thematic development.

Results: Three main themes emerged: (1) bewilderment at the unfamiliar and its overcoming, (2) confrontation with complex, ambiguous, and unstable medical conditions, and (3) psychological barriers to communication and their resolution. Initially, residents felt discomfort and emotional distance owing to unfamiliar devices, patients who were non-verbal, and the ambiguity of symptoms. However, through repeated contact, observational learning, and active participation in daily care, residents gradually developed intuitive judgment, comfort with uncertainty, and emotional connection. These experiences shifted their perceptions of children with SMID from passive and unknowable to responsive and relational. Residents also began to reconceptualize their role-not merely as problem-solvers but as care companions who tolerate ambiguity and foster connection.

Conclusions: Pediatric residents initially struggled with unfamiliarity and uncertainty in caring for children with SMID. However, sustained exposure and interprofessional learning fostered emotional growth, intuitive competence, and epistemic humility. Training programs should provide longitudinal, hands-on experiences with patients with SMID and support reflective learning to cultivate more compassionate and capable pediatricians.

Japan's cancer screening programs have expanded widely in recent decades, with local governments and workplaces offering screenings beyond national recommendations. Although this flexibility has improved access to screening, it has also contributed to overscreening and the practice of conducting tests beyond evidence-based age ranges, intervals, and methods. The underlying principles of organized screening, which emphasize evidence-based methods and quality assurance, have often been overshadowed by administrative and institutional momentum rather than by deliberate, evidence-based planning. In 2024, Miyazaki City initiated a comprehensive review of its cancer screening system under the new medical leadership. The process identified several deviations from national guidelines in target populations and screening methods, leading to a reform policy that discontinued non-evidence-based tests, such as the ABC method (a combination of serum pepsinogen and Helicobacter pylori antibody testing) for gastric cancer, breast ultrasound, and prostate-specific antigen testing. Although implementation is ongoing, this initiative demonstrates how municipalities can begin realigning screening practices with scientific standards. The Japanese case, exemplified by Miyazaki City's initiative, highlights the importance of local leadership and an organizational understanding of the principles of organized screening. Reforming overscreening requires sustained collaboration between policymakers, healthcare providers, and citizens to balance accessibility with evidence-based practices.

Recent advances in medical care have increased the number of children with medical complexity (CMC) requiring daily support, yet their opportunities for social participation remain limited. We involved a 6-year-old CMC in circus performances held in three Japanese cities. Despite medical challenges, the child safely participated and experienced psychological growth through nervousness, ambition, and communication. This initiative required close interdisciplinary collaboration and highlighted the importance of trust between families and healthcare providers. Our experience illustrates how creative, community-based efforts can reduce barriers and promote inclusion for CMCs, contributing to a more equitable and supportive society.

Rectus sheath hematoma (RSH) is an uncommon but clinically significant cause of acute abdominal pain, most often associated with anticoagulant therapy, abdominal trauma, or prior surgery. Although coughing is a recognized but rare etiology, cases without anticoagulant exposure are unusual. We report the case of a 57-year-old man with hypertension who presented with acute right abdominal pain after 1 week of persistent cough. Physical examination revealed abdominal wall discoloration, a firm mass, and a positive Carnett sign, suggesting an abdominal wall origin of pain. Laboratory evaluation showed leukocytosis and elevated inflammatory markers, and computed tomography demonstrated bronchopneumonia and multiple hematomas within the right rectus abdominis muscle. The hematomas showed high attenuation, measuring 50-75 Hounsfield units, consistent with acute hematoma. Despite initial hemodynamic stability, the patient rapidly deteriorated with tachycardia and hypotension, necessitating emergency hematoma evacuation. After intensive care and rehabilitation, he was discharged in good condition. This case highlights that cough-induced RSH, although rare, can progress rapidly to hemodynamic instability. Physicians should consider RSH in the differential diagnosis of abdominal pain with abdominal wall discoloration following coughing episodes, even in the absence of traditional risk factors, as timely recognition and intervention are essential to prevent morbidity and mortality.