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  • Shiftwork, long working hours and markers of inflammation in a national US population-based sample of employed black and white men and women aged ≥45 years

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Original research
Shiftwork, long working hours and markers of inflammation in a national US population-based sample of employed black and white men and women aged ≥45 years
  1. Raquel Velazquez-Kronen1,
  2. Leslie A MacDonald1,
  3. Tomi F Akinyemiju2,
  4. Mary Cushman3,
  5. Virginia J Howard4
  1. 1 Field Research Branch, Division of Field Studies and Engineering, National Institute for Occupational Safety and Health, Cincinnati, Ohio, USA
  2. 2 Department of Population Health Sciences, Duke University School of Medicine, Durham, North Carolina, USA
  3. 3 Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
  4. 4 Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama, USA
  1. Correspondence to Dr Raquel Velazquez-Kronen, Field Research Branch, Division of Field Studies and Engineering, National Institute for Occupational Safety and Health, Cincinnati, OH 45226, USA; ohc0{at}cdc.gov

Abstract

Objectives Work schedule demands contribute to circadian disruption and may influence health via an inflammatory response. We examined the impact of shiftwork and long work hours on inflammation in a national US sample.

Methods Participants included 12 487 employed black and white men and women aged ≥45 years enrolled in the REasons for Geographic and Racial Differences in Stroke Study who completed an occupational questionnaire (2011–2013) and clinical examination (2013–2016). Cross-sectional associations between shiftwork and work hours with log-transformed high-sensitivity C reactive protein (CRP) and white blood cell (WBC) count were examined by multiple linear regression analysis, overall and by race–sex subgroups.

Results Overall, rotating shift workers had higher log-CRP concentration compared with day workers (β=0.09, 95% CI:0.02 to 0.16) and findings for WBC were null. Black women had the highest geometric mean CRP (2.82 mg/L), while white men had the highest WBC (6.35×109/L). White men who worked afternoons had higher log-CRP compared with those who worked days (β=0.20, 95% CI: 0.08 to 0.33). Black men engaged in shiftwork <10 years working ≥55 hours/week had higher log-CRP and log-WBC compared with those working days <55 hours/week (β=0.33, 95% CI: 0.02 to 0.64 and β=0.10, 95% CI: 0.003 to 0.19). Among shift workers, non-retired white women working forward and backward shift rotations had higher log-CRP compared with those working forward only (β=0.49, 95% CI: 0.02 to 0.96).

Conclusions Shift workers had higher inflammatory markers compared with day workers and race–sex disparities should be examined further. These findings highlight a potential biological pathway linking work schedule demands and chronic disease.

  • epidemiology
  • occupational health
  • shift work schedule
  • circadian rhythm
  • cross-sectional studies

Data availability statement

Data are available upon reasonable request. This study uses data from the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. REGARDS facilitates data sharing through formal data use agreements. Requests for data access may be sent to regardsadmin@uab.edu.

http://dx.doi.org/10.1136/oemed-2023-108902

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    Data availability statement

    Data are available upon reasonable request. This study uses data from the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. REGARDS facilitates data sharing through formal data use agreements. Requests for data access may be sent to regardsadmin@uab.edu.

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    Footnotes

    • Contributors RV-K, LAM, TFA, MC and VJH conceived and designed the study, and produced an analytical plan. RV-K conducted the data analysis and drafted the manuscript. All authors interpreted the results, reviewed the manuscript and provided intellectual input. RV-K is the guarantor of the study.

    • Funding The REGARDS Study is supported by cooperative agreement (U01 NS041588) co-funded by the National Institute of Neurological Disorders and Stroke (NINDS), National Institute on Aging (NIA), National Institutes of Health, and Department of Health and Human Services. The occupational ancillary study is supported by intramural funding by the National Institute for Occupational Safety and Health (NIOSH), and Centers for Disease Control and Prevention (CDC).

    • Disclaimer The content is solely the responsibility of the authors and does not necessarily reflect the official views of NINDS, NIA, CDC or NIOSH. Representatives of the NINDS were involved in the review of the manuscript but were not directly involved in the collection, management, analysis or interpretation of the data.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.