Study design and participants
This study is a cost-effectiveness analysis of a randomized, controlled, parallel-group trial that compared a combined cognitive and vocational intervention to multidisciplinary TAU on employment and other clinical outcomes after mild and moderate TBI. Details of the study design, recruitment, randomisation, blinding and data collection are provided in the study protocol [
12]. Briefly, the trial was conducted at a specialized TBI outpatient clinic at Oslo university hospital (OUH), Norway, where patients were randomised to a group-based compensatory cognitive training intervention and individualized supported employment (CCT-SE) or individualized outpatient treatment provided by a multidisciplinary team (TAU) in a 1:1 ratio. Participants were recruited and started treatment 8–12 weeks after sustaining a mild or moderate TBI and received the intervention or control group treatment for a total of 6 months.
The trial was performed in accordance with the Declaration of Helsinki, and registered at ClinicalTrials.gov on 28.03.2017 (#NCT03092713). One-hundred and sixteen individuals aged 18–60 years were recruited to the RCT between July 2017 and April 2019. Two participants dropped out from the CCT-SE group and 1 from the TAU group after randomization. See Additional file
1 for flow chart of participant recruitment. Participants had sustained a mild or moderate TBI assessed by a Glasgow Coma Scale (GCS) score of 10–15, loss of consciousness for < 24 h and post-traumatic amnesia for < 7 days. Criteria from the American Congress of Rehabilitation Medicine were used to establish the presence of mild TBI [
13]. All participants were employed in a minimum 50% position at the time of injury, but sick listed 50% or more due to post-concussive symptoms assessed by the Rivermead Post Concussion Symptoms Questionnaire [
14] 2–3 months post injury. Table
1 provides participants’ demographic, injury- and work-related characteristics at baseline, in addition to EQ-5D-5L index values. There were no statistically significant between group differences on baseline characteristics, with the exception of EQ-5D-5L index values (
p = 0.013). See Additional file
2 for proportion of responses by level of severity for EQ-5D-5L dimensions at baseline per treatment group.
Table 1
Baseline characteristics of participants in the treatment groups
Demographic information |
Age, mean (SD) | 41 (10) | 44 (9) |
Gender (female), n (%) | 33 (55) | 36 (64) |
Education, mean (SD) | 16 (2) | 16 (3) |
Marital status, n (%) |
Married/co-habitant | 43 (72) | 34 (61) |
Divorced/separated/single | 17 (28) | 22 (39) |
Clinical information |
Cause of injury, n (%) (n = 115) |
Fall | 19 (32) | 30 (54) |
Transport | 12 (20.5) | 11 (20) |
Other | 28 (47.5) | 15 (26) |
GCS, median (range) (n = 114) | 15 (10–15) | 15 (11–15) |
LOC, n (%), (n = 115) |
None | 31 (51.5) | 30 (54.5) |
< 30 min | 21 (35) | 16 (29) |
< 24 h | 1 (2) | 2 (4) |
Not registered | 7 (11.5) | 7 (12.5) |
PTA, n (%), (n = 115) |
None | 25 (42) | 26 (47) |
< 1 h / < 24 h | 25 (41.5) | 26 (56) |
< 7 days | 0 (0) | 2 (4) |
Not registered | 10 (16.5) | 1 (2) |
Trauma-related CT/MRI findings, n (%) |
Yes | 11 (18) | 16 (29) |
No | 45 (75) | 35 (62) |
No CT/MRI | 4 (7) | 5 (9) |
AIS head score, n (%) |
Minor | 34 (57) | 25 (44.5) |
Moderate | 18 (30) | 16 (28.5) |
Serious / Severe | 8 (13) | 15 (27) |
Extracranial injuries (yes), n (%) | 28 (47) | 25 (45) |
Work factors |
Occupation type (white collar), n (%) | 53 (88) | 50 (89) |
Occupation category, n (%) |
Military/Academic professions | 30 (50) | 28 (50) |
Leaders | 15 (25) | 13 (23) |
Office/Sales | 10 (17) | 9 (16) |
Craft/Machine | 5 (8) | 6 (11) |
Operators/Transportation/Cleaning |
Employment duration (months), median (IQR), (n = 114) | 54 (114) | 42 (108) |
Full time position (yes), n (%) | 55 (92) | 48 (86) |
Enterprise size, n (%) |
< 250 employees | 33 (55) | 40 (71.5) |
> 250 employees | 27 (45) | 16 (28.5) |
Sick listed, n (%) 80–100% 50–79% | 48 (80) 12 (20) | 46 (82) 10 (18) |
EQ-5D-5L |
Index value, mean (SD) | 0.648 (0.152) | 0.713 (0.116) |
Study interventions
CCT is a manualised intervention targeting post-concussive symptom management and cognitive symptoms [
15,
16]. The intervention was provided by a clinical psychologist and a MD in groups of two to five participants for 2 h weekly over 10 weeks. Each session covered the topics through a combination of psychoeducation and compensatory strategy training. The vocational part of the intervention was based on elements from the Individual Placement and Support model of SE [
12,
17]. Follow-up was customised to the individual participants’ needs and entailed mapping resources, limitations and work tasks, followed by guidance, advice and work task accommodations. The SE intervention was provided by three employment specialists for a total of 6 months. The CCT and SE interventions were provided in parallel and therapists providing the interventions collaborated closely to ensure implementation of strategies and compensatory techniques at the workplace.
TAU consisted of assessment and treatment provided by a multidisciplinary team (physiatrist, neuropsychologist, physiotherapist, occupational therapist and social worker) at a specialized TBI outpatient clinic at the Dept. Of Physical Medicine and Rehabilitation, OUH. Follow-up consisted of individual contacts and an education group focused on nonspecific education about TBI and discussion of common problems in daily life following TBI. The education group consisted of four weekly meetings of 2 h, each led by a different professional. TAU was provided for a maximum of 6 months.
Information regarding the use of healthcare services, informal care and sickness absence was collected at 3, 6 and 12 months after study inclusion. The information was self-reported by the participants, including only trauma-related treatment and follow-up, using a questionnaire specifically designed for that purpose (developed by EAA). The questionnaire included number of visits to a general practitioner, physical therapist, chiropractor, contract specialists (dentist, neurologist, ophthalmologist, orthoptist/optician, otorhinolaryngologist and psychologist) and out-of-pocket services (naprapath and osteopath). Information about informal care was collected by asking participants if they had received informal care by friends or family since last follow-up and, if so, number of hours receiving assistance per week. We also recorded information about gross annual salary and productivity loss, which included work status in terms of sickness absence (percentage and duration) at each follow-up. We did not assess the use of medications, distance and transportation related to the healthcare utilisation and, hence, could not calculate medication and transportation costs. The cost of productivity loss was based on the participant’s gross annual salary, and was calculated by subtracting weekly wage for full time work (i.e., pre-injury level of work) from weekly wage for actual number of hours worked per week at each follow-up (i.e., taking into account sickness absence). Costs of informal care was calculated using the opportunity cost method (i.e. time spend providing informal care was valued as paid working time [
18], multiplying the mean hourly wage in Norway [
19] by number of hours of informal care per week. Health service utilisation and related costs, including formal primary and secondary care reimbursed by the government, were categorized according to the CCT-SE and TAU groups. Total care costs also included informal care and out-of-pocket services (i.e. services not reimbursed by the government). Total societal costs comprised total care costs in addition to costs related to productivity loss. Cost categories and unit costs are presented in Table
2. The majority of unit costs were based on the reimbursement schemes. Costs were estimated on a present-value basis of Euro (€) in 2019 (€1 = Norwegian Kroner [NOK] 10).
Table 2
Cost categories, units, valuation and unite price in Euro
Primary care |
General practitioner | Per visit | 50 | NOMA, 2019-2020, general practitioner consultation |
Physiotherapist, assessment | 1 h | 92 | The Norwegian Physiotherapy Association, 2019 |
Physiotherapist, treatment | 30 min | 62 | The Norwegian Physiotherapy Association, 2019 |
Psychologist, assessment | 1 h | 141 | HELFO, 2020 |
Psychologist, treatment | 1 h | 110 | HELFO, 2020 |
Chiropractor, assessment | Per visit | 30 | HELFO, 2020 |
Chiropractor, treatment | Per visit | 14 | HELFO, 2020 |
Contract specialists |
Neurology | Per assessment | 131 | NOMA, 2019-2020, specialist health service consultation |
Dentistry | Per assessment | 159 | HELFO, 2020 |
Ophthalmology | Per assessment | 101 | NOMA, 2019–2020, specialist health service consultation |
Otorhinolaryngology | Per assessment | 94 | NOMA, 2019–2020, specialist health service consultation |
Optometry/orthoptics | Per assessment | 94 | NOMA, 2019–2020, specialist health service consultation |
Informal care |
| Per hour | 32 | Statistics Norway, 2019 |
Production loss* |
Gross wage | Per hour | 35 | Self-reported income |
Out-of-pocket |
Naprapathy | Per visit | 70 | Estimate |
Osteopathy | Per visit | 90 | Estimate |
Statistical analysis
Descriptive statistics were used to present participants’ characteristics, costs of the CCT-SE intervention and TAU, health- and informal care and productivity loss, with mean and standard deviation (SD) or median and inter-quartile range (IQR) for continuous variables, and proportions and percentages or range for categorical variables.
In the cost-effectiveness analysis, the differences in outcomes of CCT-SE and TAU were compared to difference in costs.
The primary cost-effectiveness analysis was defined by the incremental cost-effectiveness ratio (ICER), given by
$$ICER=\frac{{Costs}_{CCT-SE}-{Costs}_{TAU}}{\left({\#days back to work}_{CCT-SE}-{\#days back to work}_{TAU}\right)*(-1)}=\frac{incremental costs}{\#days earlier back to work}$$
(1)
where the nominator in Eq. (
1) is the incremental cost, while the denominator in Eq. (
1) can be interpreted as number of days earlier back to pre-injury work level in the CCT-SE group. The costs included in the primary analysis were total healthcare costs (i.e., costs of the CCT-SE intervention or TAU and other healthcare services).
The secondary cost-effectiveness analysis was based on QALYs as the health outcome. There were 15 participants with missing EQ-5D-5L values. The two missing values in the TAU group at baseline were replaced by the average value for the TAU group. When a participants had a missing observation between two observation points on the time line, we assumed the relationship between the adjacent recorded observations to be linear. For instance, for missing values at 3 months we assumed a linear trend from the observations at baseline to 3 months was carried onwards to 6 months. Further, for participants with reported EQ-5D-5L at baseline and 3 months, but not at 6 and 12 months, we assumed that the trend from baseline to 3 months were carried onwards to 6 months, which resulted in two additional observations being replaced. For missing values at 12 months, we assumed the same EQ-5D-5L value as observation at 6 months, which resulted in 11 observations being replaced.
We estimated the QALYs for each individual by area under the curve (AUC), where we used the EQ-5D-5L values at baseline, 3, 6 and 12 months follow-ups and assumed linear changes in HRQoL over time [
22]. From Table
1 we observed that the EQ-5D-5L baseline values were significantly different between CCT-SE and TAU (
p = 0.013). To adjust for the difference, we applied two methods. Firstly, based on the method presented by Manca et al. [
22], we used regression analysis to adjust estimated QALYs for EQ-5D-5L value at baseline and treatment group (see Additional file
4). Secondly, we parallel shifted the observation for the intervention group upwards and equal to the difference at baseline, equal to 0.065. Analysis based on the raw data are presented in Additional file
5. The costs included both total healthcare and societal costs. Lastly, we have included an analysis comparing the improvement in HRQoL values from baseline to 12 months. In this alternative, the incremental effect will be interpreted as the difference in incremental improvement on the HRQoL value over the 12 months follow-up period.
For the secondary cost-effectiveness analysis where QALYs were the main health outcome, we estimated the net monetary benefit (NMB), which is defined by
$$NMB=Incremental QALYs* \lambda -Incremental costs$$
(2)
where λ refers to the threshold value for a QALY gained. If the NMB is lower or equal to zero, the intervention is considered cost-effective. According to Norwegian guidelines the threshold value depends on the severity of the condition defined by the absolute shortfall (number of lost years in good health), and varies from about € 27 500 to € 1 000 00 [
23]. In the estimation of NMB, we applied € 27 500 as the threshold value.
To estimate cost-effectiveness with the change in HRQoL from baseline to 12 months, the results were presented by ICER, defined by Eq. (
1) with differences in change in HRQoL.
To account for uncertainty in the outcomes (number of days back to work, QALYs, change in HRQoL and costs) between individuals, we conducted a sensitivity analysis by the bootstrap methods with replacement including 1000 iterations. The results of the 1000 iterations of mean ICERs are presented in a cost-effectiveness plane, and for the secondary cost-effectiveness analysis the cost-effectiveness acceptability curves (CEACs) were presented, reporting the likelihood of the CCT-SE intervention to be cost-effective (number of simulations falling below the threshold) according to different threshold values.