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Premorbid risk factors influencing labour market attachment after mild traumatic brain injury: a national register study with long-term follow-up
  1. Heidi Jeannet Graff1,
  2. Volkert Siersma2,
  3. Anne Møller3,4,
  4. Jakob Kragstrup5,
  5. Lars L Andersen6,
  6. Ingrid Egerod7,
  7. Hana Malá Rytter8,9
  1. 1 Department of Anaesthesia, Centre of Head and Orthopaedics, University Hospital Rigshospitalet, Copenhagen, Denmark
  2. 2 Department of Public Health, The Research Unit for General Practice and Section of General Practice, University of Copenhagen, Copenhagen, Denmark
  3. 3 Department of Occupational Medicine and Social Medicine, Copenhagen University Hospital Holbaek, Holbaek, Denmark
  4. 4 Department of Public Health, The Research Unit for General Practice and Section of General Practice, University of Copenhagen, Copenhagen, Denmark
  5. 5 Department of Public Health, The Research Unit for General Practice and Section of General Practice, University of Copenhagen, Copenhagen, Denmark
  6. 6 Musculoskeletal disorders and physical workload, National Research Centre for the Working Environment, Copenhagen, Denmark
  7. 7 Department of intensive care, Centre for Cancer and Organ Diseases, University Hospital Rigshospitalet, Copenhagen, Denmark
  8. 8 Department of Psychology, Faculty of Social Science, University of Copenhagen, Copenhagen, Denmark
  9. 9 Department of Neurology, University Hospital Bispebjerg-Frederiksberg, Copenhagen, Denmark
  1. Correspondence to Heidi Jeannet Graff; heidi.graff{at}


Objectives Some patients with mild traumatic brain injury (mTBI) experience persistent postconcussive symptoms, influencing the ability to work. This study assessed associations between mTBI and labour market attachment (up to 5 years postinjury) in patients with different premorbid characteristics.

Design and setting Danish national cohort study with 5-year register follow-up.

Participants We included hospital admitted patients between 18 and 60 years diagnosed with mTBI (International Classification of Diseases, version 10 diagnosis S06.0) (n=19 732). For each patient, one control was selected matched on age, gender and municipality (n=18 640).

Primary outcome measure Primary outcome was ‘not attending ordinary work’, and premorbid risk factors were cohabitation status, education, ethnicity, gender, age and comorbidities.

Results The odds of not attending ordinary work increased from 6 months to 5 years. The highest increased odds (approximately twice as high for patients) of not attending ordinary work at 5 years were found in the highest educational group (OR 2.15, 95% CI 1.78 to 2.59), for patients of non-Danish origin (OR 1.98, 95% CI 1.52 to 2.57), for patients between 30 and 39 years (OR 1.93, 95% CI 1.68 to 1.23) and for patients with somatic comorbidities (OR 1.81, 95% CI 1.38 to 2.37). Contrary to expectations, we did not find higher odds in patients with psychiatric diagnoses (OR 1.12, 95% CI 0.76 to 1.60).

Conclusions Important premorbid characteristics for lower labour market participation after mTBI were higher education, non-Danish origin, age 30–39 years and having somatic comorbidities. Demographic and health-related variables should be considered when assessing patients with mTBI at risk of long-term sickness absence.

Trial registration number NCT03214432; Results.

  • labour market attachment
  • risk factors
  • mild traumatic brain injury
  • register study

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  • Contributors All authors participated in the study design, interpretation of the data and revising it critically. HJG obtained the funding, drafted the protocol and manuscript. HJG and VS performed the statistical analyses. AM, LA, JK, IE and HMR participated in the study design and conceptualisation. All authors approved the final manuscript.

  • Funding This work was supported by the Research Foundation, Rigshospitalet (E-22260-03) (E-23473-01), the Danish Health Foundation (Helsefonden) (16-B-0050) and the Aase and Ejnar Danielsen’s Foundation (20-000054).

  • Competing interests None declared.

  • Ethics approval The study was approved by the Danish Data Protection Agency (Datatilsynet) no (05179 - RH-2016-389). The study protocol was registered on on 5 July 2017 ( Identifier: NCT03214432).

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

  • Data sharing statement No additional data are available.

  • Patient consent for publication Not required.

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