Journal of Preventive Medicine and Public Health

Brief Report

Long Working Hours and Risk of Ischemic Heart Disease Among Japanese Workers: The Jichi Medical School Cohort Study: Mayumi Saiki, Akizumi Tsutsumi, Jian Li; J Prev Med Public Health. 2026;59(2):211-218. Published online February 5, 2026; DOI: https://doi.org/10.3961/jpmph.25.577

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Abstract Summary PDF Supplementary Material: Objectives
Karoshi, or “death from overwork,” has been recognized for decades; however, epidemiological findings regarding long working hours (LWH) and ischemic heart disease (IHD) remain inconsistent. This study aimed to provide new evidence on the association between LWH and IHD, while accounting for job strain among Japanese workers, both male and female.
Methods
This study utilized data from 6670 workers participating in the Jichi Medical School Cohort Study. Baseline working hours were categorized as <5.0, 5.0 to 6.9, 7.0 to 8.9 (reference), 9.0 to 10.9, and ≥11.0 hr/day. Fatal and non-fatal incident IHD cases were determined during follow-up using International Classification of Diseases, 10th revision codes. Multivariable Cox proportional hazards models were used to examine associations, adjusting for socio-demographic factors, lifestyle behaviors, cardiometabolic characteristics, and job strain.
Results
During a mean follow-up of 12 years, 58 incident IHD cases (42 male and 16 female) were documented. Long working hours (≥11.0 hr/day) were significantly associated with an increased risk of IHD in the total sample (hazard ratio, 2.92; 95% confidence interval, 1.15 to 7.39), and the overall pattern of associations was similar in sex-stratified analyses.
Conclusions
These findings suggest that LWH independently increases the risk of IHD among Japanese workers, even after adjustment for job strain, underscoring the importance of managing working hours to reduce karoshi in both male and female workers.; Summary

Key Message
Our study provides new evidence on the association between long working hours (LWH) and ischemic heart disease (IHD), while accounting for job strain among Japanese workers, both male and female, utilizing data from the Jichi Medical School Cohort Study. Our study revealed that LWH (≥11.0 hr/day) were significantly associated with an increased risk of IHD in the total sample (hazard ratio, 2.92; 95% confidence interval, 1.15 to 7.39). These findings suggest that LWH increase the risk of IHD among Japanese workers, underscoring the importance of managing working hours to reduce karoshi in both male and female workers.

Original Article

Associations of Workplace Violence With Cardiovascular Disease Among United States Workers: Findings From a National Survey: Zheyu Hu, Jian Li; J Prev Med Public Health. 2023;56(4):368-376. Published online July 10, 2023; DOI: https://doi.org/10.3961/jpmph.23.032

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Objectives
Recent research indicates a potential association between workplace violence and an increased risk of cardiovascular disease (CVD) in the working-age population. However, the relevant evidence in the United States is sparse. Thus, this study was conducted to explore the possible relationship between workplace violence and CVD among United States workers.
Methods
We utilized cross-sectional data from the 2015 National Health Interview Survey, which included a representative sample of 18 380 workers, to investigate the associations between workplace violence and the prevalence of CVD using logistic regression. Workplace violence was determined based on self-reported threats, bullying, or harassment at work over the past 12 months, supplemented with additional information regarding frequency. CVD included all forms of heart disease and stroke.
Results
A total of 1334 workers reported experiences of workplace violence, and 1336 workers were diagnosed with CVD. After adjustment for covariates, participants who reported any instance of workplace violence had significantly higher odds of having CVD (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.35 to 2.30) than those who reported no such violence. Furthermore, the highest odds of CVD (OR, 1.80; 95% CI, 1.23 to 2.63) were observed among those frequently exposed to workplace violence. Even occasional exposure to workplace violence was associated with 74% excess odds of CVD.
Conclusions
Our study indicates an association between workplace violence and CVD in United States workers, exhibiting a dose-response pattern.

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Citations

Citations to this article as recorded by

Work as a social determinant of health on cardiovascular and musculoskeletal diseases: A literature review
Anjanette Wells, Melissa Previtera, Michael Markey, Kelly J Brunst, Marepalli Rao, Emily A Adkins, Tongfan Wu, Julia Rodner, Amit Bhattacharya
WORK: A Journal of Prevention, Assessment & Rehabilitation.2025; 82(2): 578. CrossRef
The Role of Transformational Leadership in Prevention of Workplace Bullying and Psychosomatic Disorders in Non-university Women Teachers
Pedro R. Gil-Monte, Begoña Espejo, Irene Checa, Pedro Gil-LaOrden
International Journal of Bullying Prevention.2025;[Epub] CrossRef
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Cuadernos de Administración.2024; 40(80): e2213596. CrossRef

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