Return to Work After Mild Traumatic Brain Injury

Background:

Patients with mild traumatic brain injury can to some extend experience long-term physical, cognitive, social and behavioral deficits, which have serious implications for employment trajectories and financial independence. These deficits have shown to be more pronounced in women. High socio-economic position such as income, level of education and employment status before the accident have shown to affect return to work. But also cohabitation status, ethnicity and health are important factors. Previously studies are typically self-report studies, and are often small and may suffer from selection bias due to patient nonresponse.

Aim:

The aim of this study is to describe no return to work among patients with mild traumatic brain injury in Denmark and to examine how factors such as age, gender, cohabitation status, socio-economic and pre-injury health factors affect no return to work up to 5 years post-injury.

Hypothesis:

We hypothesize that most patients with mild traumatic brain injury return to work within work 6 months post-injury, and that patients with mild traumatic brain injury injury receive more social transfer payments compared to the general population.

Additionally, we hypothesize that low socio economic position, comorbidities and being single are associated with prolonged no return to work.

Methods:

The present study is an observational national register-based cohort study with long-term follow up of patients with mild traumatic brain injury from 1st of January 2008 - 31st of December 2012 in Denmark. Patients aged 18-60 years diagnosed with concussion from 1st of January 2003-31st of December 2007 in the national patient register will be included in the study. Data will be retrieved from several national databases, including the DREAM database containing data on social benefits and reimbursements.

Primary outcome is no-return to work (nRTW) due to any cause and the following four secondary outcomes are graded and should be regarded as a continuum ranging from health related nRTW, limited nRTW, permanently nRTW and mortality.

The results will be published as two separate scientific articles.

Study Overview

• Status: Completed
• Conditions: Mild Traumatic Brain Injury; Concussion, Mild

• Study Type: Observational
• Enrollment (Actual): 38372

Contacts and Locations

Study Locations

• Denmark
  • Copenhagen K
    • Copenhagen, Copenhagen K, Denmark, 1353
      • Department of psychology, University of Copenhagen

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 60 years (ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

Patients with mild traumatic brain injury were hospital admitted, emergency or outpatient treated and identified on the basis of ICD-10 codes in the National Patient Register from the 1st of January 2003 - 31st of December 2007.

Patients were included if they were registered in the national patient register database with concussion (ICD-10 S06.0) as primary diagnosis.

Description

Inclusion Criteria:

• ICD-10 code for concussion as action diagnosis (ICD-10: S06.0)
• Working age adults between 18-60 years old at the time of injury
• Gainfully occupied or deemed available for work the week preceding the time of injury

Exclusion Criteria:

• Patients were excluded if they were hospital treated and diagnosed with other major neurological injuries such as spinal cord and column injuries and traumatic brain injuries (TBI) besides the concussion at baseline.
• Patients were excluded, who 5 years prior to baseline (1st of January 1998 - 31st of December 2002) had sustained major neurological impairments including concussions.
• Patients outside of the age limit
• Patients not resident in Denmark
• Patients on unemployment benefits and not economically active at the time of injury

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
mild traumatic brain injury cohort; Patients with mild traumatic brain injury were defined as hospital admitted, emergency or outpatient treated, who were assigned the ICD-10 code for concussion (ICD-10 S06.0) in the national patient register at hospital discharge from the 1st of January 2003 - 31st of December 2007. Patients were working age adults between 18-60 years old and gainfully occupied or deemed available for work the week before the injury.
non-injured control group; Controls were randomly selected from the Population register who were between 18-60 years old, had no diagnosis of mild traumatic brain injury during the period 1st of January 2003 - 31st of December 2007 and were gainfully occupied or deemed available for work the week preceding the time of injury. One control was matched for each mTBI case on gender, municipality and age (year of birth +/- 0,5 years). In case of no matching control the age criterion was expanded to (year of birth +/- 1 year), if still no matching control the age criterion was further expanded to (year of birth +/- 2 year). Additionally, controls were excluded according to the same criteria as the included cases.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
nRTW	No-return to work up to 5 years post-injury. nRTW is defined as receiving social transfer payments in any given week during the follow-up period. If no social benefit is given in the DREAM register, it is assumed the patient is gainfully occupied or self-supporting.	5 years follow up

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Health related nRTW	Health related nRTW is defined as a combined effect of social transfer payments given in case of short or long-term sickness absence. If social transfer payments are granted due to illness it is assumed that the patient is not gainfully working or job seeking.	5 years follow up
Limited nRTW	Limited nRTW is defined as a joint effect of several outcome measures granted citizens with permanent reduced work capacity. If no social transfer payments are given, it is assumed that the patients are gainfully occupied or self-supporting.	5 years follow up
Permanently nRTW	Individuals between 18-60 years who have permanently reduced work capacity and unable to return to work after injury can be granted disability pension (DP) after an extensive municipal assessment. DP would only be granted persons who have no work capacity left. This outcome includes disability pension and mortality and is regarded as a permanent exit from the labour market.	5 years follow up
Mortality	Data on mortality was retrieved from the DREAM register and the proportion of mortality will be assessed during the 5 year follow-up period.	5 years follow up

Collaborators and Investigators

• Sponsor: University of Copenhagen
• Collaborators: Rigshospitalet, Denmark; Sygekassernes Helsefond

Publications and helpful links

General Publications

• Graff HJ, Siersma V, Moller A, Kragstrup J, Andersen LL, Egerod I, Mala Rytter H. Premorbid risk factors influencing labour market attachment after mild traumatic brain injury: a national register study with long-term follow-up. BMJ Open. 2019 Apr 11;9(4):e027297. doi: 10.1136/bmjopen-2018-027297.
• Graff HJ, Siersma V, Moller A, Kragstrup J, Andersen LL, Egerod I, Mala Rytter H. Labour market attachment after mild traumatic brain injury: nationwide cohort study with 5-year register follow-up in Denmark. BMJ Open. 2019 Apr 11;9(4):e026104. doi: 10.1136/bmjopen-2018-026104.

Study record dates

Study Major Dates

• Study Start (ACTUAL): July 1, 2017
• Primary Completion (ACTUAL): July 4, 2018
• Study Completion (ACTUAL): July 4, 2018

Study Registration Dates

• First Submitted: July 5, 2017
• First Submitted That Met QC Criteria: July 10, 2017
• First Posted (ACTUAL): July 11, 2017

Study Record Updates

• Last Update Posted (ACTUAL): July 6, 2018
• Last Update Submitted That Met QC Criteria: July 4, 2018
• Last Verified: July 1, 2018

More Information

Terms related to this study

• Keywords: Concussion; Labour market affiliation; Mild traumatic brain injury; Return to work; Disability pension; Sickness absence; Long-term sickness absence
• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Craniocerebral Trauma; Trauma, Nervous System; Head Injuries, Closed; Wounds, Nonpenetrating; Brain Injuries; Wounds and Injuries; Brain Injuries, Traumatic; Brain Concussion
• Other Study ID Numbers: mTBI-HJG-2017

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No