Design of an early intervention for persistent post-concussion symptoms in adolescents and young adults: A feasibility study

Abstract

BACKGROUND:

About 5–15 % of patients with concussion experience persistent post-concussion symptoms (PCS) longer than 3 months post-injury.

OBJECTIVE:

To explore the feasibility of a new intervention for young patients with persistent PCS and long-term changes after intervention.

METHODS:

Thirty-two consecutive patients (15–30 years) with persistent PCS 2–4 months post-injury were recruited from a cohort study or referred to a non-randomized feasibility study of an individually tailored, 8-week, multidisciplinary intervention. Assessment was performed at baseline, end of intervention (EOI), and at 3- and 12-month follow-up (FU). Main measures were The Experience of Service Questionnaire (ESQ), Rivermead Post-Concussion Symptoms Questionnaire (RPQ) and The Quality of Life after Brain Injury - Overall Scale (QOLIBRI-OS).

RESULTS:

Twenty-three (72%) patients completed the intervention. The ESQ demonstrated high patient satisfaction. There was a decrease of PCS and an increase in quality of life from baseline to EOI: RPQ score –8.9 points, 95% CI 4.5 to 13.3, p < 0.001; QOLIBRI-OS score +10.5 points, 95% CI 2.5 to 18.5, p = 0.010. Improvement was maintained at 3- and 12-month FU.

CONCLUSION:

The new early intervention is feasible and may prevent chronification of PCS. An RCT is currently performed to evaluate the effect of the intervention.

Keywords

Brain concussion behavior therapy early intervention feasibility study mild traumatic brain injury post-concussion syndrome rivermead post-concussion symptoms questionnaire

1 Introduction

Concussion, the mildest form of traumatic brain injury (Prigatano & Gale, 2011), is an important public health concern (Carroll, Cassidy, Holm et al., 2004; Holm, Cassidy, Carroll & Borg, 2005). According to a WHO Task Force, the incidence of hospital-treated concussions is about 100–300/100,000, whereas the incidence in the community is estimated to be 600/100,000 due to an additional (unknown) number of cases never seen in hospitals (Cassidy et al., 2004). Although complete resolution normally occurs within the first weeks after a concussion, a subset of 5–15% or more continue to experience physical, cognitive and emotional post-concussion symptoms (PCS) such as headaches, dizziness, fatigue, concentration problems and depressed mood (Cassidy et al., 2004; Iverson, 2005; Ponsford, 2005; Snell, Surgenor, Hay-Smith, & Siegert, 2009). Prospective studies have shown that patients who suffer from impairing PCS at 3 months (i.e. PCS that occur frequently to the extent of impairing the daily activities of the patient) are at risk of developing persistent symptoms (Hou et al., 2012; Ponsford et al., 2012). Accordingly, reviews conclude that 3 months may be defined as the upper threshold for the subacute spontaneous recovery phase in mixed-mechanism concussions and that persistent PCS may be defined as symptoms extending beyond this time frame (Carroll, Cassidy, Peloso et al., 2004). This is in contrast to sports-related concussions where recent consensus guidelines suggest that the expected time frame for recovery is 10–14 days (McCrory et al., 2017). Persistent PCS are associated with reduced health-related quality of life and a risk of permanently reduced work ability (Hou et al., 2012; King, 2003; McCrea et al., 2009).

Current research suggests that the development of persistent PCS is best understood in terms of a biopsychosocial disease model (Al Sayegh, Sandford, & Carson, 2010; Hou et al., 2012; McCrea et al., 2009; Ruff, 2011; Silverberg & Iverson, 2011). Predisposing factors may be various demographic and clinical variables such as age, sex, and pre-injury psychiatric and physical history, whereas perpetuating factors may be emotional, cognitive, and behavioral reactions to PCS (Broshek, De Marco, & Freeman, 2015; Carroll et al., 2004; Junn, Bell, Shenouda, & Hoffman, 2015; Ponsford et al., 2012; Stulemeijer, van der Werf, Borm, & Vos, 2008). Recent studies have shown that negative illness perceptions and maladaptive illness behaviour early after concussion are associated with worse prognosis (Hou et al., 2012; Snell, Hay-Smith, Surgenor, & Siegert, 2013; Stulemeijer et al., 2008; Whittaker, Kemp, & House, 2007). Examples of negative illness perceptions associated with persisting PCS are the beliefs that one cannot control the symptoms, that they will persist and that they are signs of brain damage (Hou et al., 2012; Whittaker et al., 2007). Negative illness perceptions are associated with maladaptive illness behaviour such as fear-avoidance behavior, where fear of provoking unpleasant PCS leads to avoidance of adaptive behaviors (Broshek et al., 2015; Samwel, Kraaimaat, Crul, & Evers, 2007). Other maladaptive illness behaviors may be excessive rest or the opposite, exertion (“pushing through symptoms”), or oscillations between periods with very low and very high levels of physical and mental activity, often referred to as “all-or-nothing behaviour” (Hou et al., 2012; Junn et al., 2015; Potter & Brown, 2012; Silverberg & Iverson, 2013). These may be conceptualized as behavioral attempts to manage or to reduce PCS, while actually maintaining PCS, because “vicious circles” may develop. For example, excessive rest may lead to reduced physical and mental stamina so that less and less activity may trigger symptoms, which then again may lead to even more rest. Another example may be how exertion may trigger stress symptoms which then again exacerbate PCS. Based on these findings, both negative illness perceptions and maladaptive illness behaviors may be viable targets for intervention (Snell et al., 2013).

Intervention programmes for chronic PCS have so far yielded insufficient evidence in clinical trials. Accordingly, recent reviews advocate for high-quality studies evaluating early, behavioral interventions (Al Sayegh et al., 2010; Boussard et al., 2014; Marshall et al., 2015; Williams, Potter, & Ryland, 2010). Preliminary evidence from a limited number of trials suggests that cognitive behavioral therapy (CBT) may be effective in treating persistent PCS (Al Sayegh et al., 2010; Junn et al., 2015; Potter & Brown, 2012; Silverberg et al., 2013; Snell et al., 2009). However, traditional CBT must be performed by trained therapists, and therefore it is not likely to be a feasible intervention to a larger group of at-risk patients. Another promising behavioral intervention may be to support gradual return to daily activities, i.e. sustainable, gradual increases in levels of activity in intensity and/or duration over time (Junn et al., 2015; Ponsford, 2005; Potter & Brown, 2012). Such an intervention could easily be delivered by e.g. physiotherapists and occupational therapists.

We developed an early intervention for adolescents and young adults with PCS lasting more than 3 months based on principles from CBT and gradual return to activities. The intervention was designed to be performed by physiotherapists and occupational therapists as main treatment providers to enable later implementation in primary care or municipality settings. The current study was performed prior to a randomized controlled trial (RCT) and aimed to assess: (1) the feasibility of the new intervention programme, more specifically recruitment methods, recruitment rates, adherence, follow-up rates and patient satisfaction, and (2) the change in PCS, health-related quality of life, illness perceptions and illness behavior immediately and up to one year after the intervention.

2 Methods

2.1 Design and setting

The present, non-randomised feasibility study was partly embedded in an ongoing cohort study financed by budget funds earmarked for strengthening the treatment options for 15- to 30-year-old patients with concussion or brain injury. The impetus for this funding was a health technology assessment performed in Denmark in 2011 concluding that special effort was needed to improve the detection and rehabilitation of patients in this age group.

In the cohort study, young patients diagnosed with concussion at public hospitals in Central Denmark Region from 2013–2017 were identified in an administrative hospital register and followed by means of questionnaires to assess their prognosis. From February 2014 – February 2015, consecutive patients were recruited to the present study based on symptom severity 2–3 months after diagnosis. In addition, patients could be referred by General Practitioners (GP) in Central Denmark Region, including approx. 800 GPs. In Denmark, all citizens are entitled to free medical health care from public insurance. The GP serves as a gate-keeper of referrals to all other health services. Patients received no financial reimbursement for participation.

A preliminary evaluation was performed in December 2014 dividing the study in two phases (see Fig. 1). The assessment and subsequent intervention was carried out in a general hospital setting at Aarhus University Hospital, Denmark.

Fig.1

Patient flow, structure of the intervention and assessment points. The timeline represents median time range in months after concussion at the four assessment points with “0 months” being the time of injury. FU = follow-up. Baseline: 4 months (2,6–6,3 months); End of intervention: 7 months (5.4–9.9 months); 3-month FU: 11 months (8.4–15.8 months); 12-month FU: 22 months (17.5–25.4 months).

2.2 Participants

Patients were recruited based on the following inclusion criteria: 1) Concussion within the last 2–4 months according to the diagnostic criteria recommended by the WHO Task Force (Carroll et al., 2004), 2) a direct contact between the head and an object (in order to rule out primary acceleration-deceleration traumas), 3) age 15–30 years at the time of the head trauma, 4) ability to speak and read Danish, 5) a score of≥20 points on the Rivermead Post-Concussion Symptoms Questionnaire (RPQ) (King, Crawford, Wenden, Moss, & Wade, 1995). Patients were excluded in case of 1) objective findings indicating neurological disease or brain damage, 2) previous concussion within the last 2 years leading to persistent PCS, 3) severe active substance abuse, and 4) severe psychiatric, neurological or other medical disease that would impede participation in the intervention.

Participation in the study was voluntary. Patients were informed about the feasibility nature of the study and included after oral informed consent. The National Committee on Health Research Ethics was consulted by email on January 20, 2014 in accordance with national guidelines. The study was approved by the Danish Data Protection Agency (no. 1-16-02-23-15). Data was kept confidential.

2.3 Procedures

2.3.1 Clinical assessment and advice

Patients with persisting PCS were invited to participate in the study by mail, and at the same time they were scheduled for a thorough clinical assessment performed by two physicians to determine eligibility. It consisted of 1) a baseline questionnaire, 2) a neurological examination, and 3) a standardized psychiatric interview based on items from Schedules for Clinical Assessment in Neuropsychiatry (SCAN) (Wing et al., 1990) and the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) (Ambrosini, 2000). Moreover, psychological distress was assessed by the eight-item version of The Symptom Checklist (SCL-8) derived from the anxiety and depression subscales from SCL-90-R (Fink et al., 2004) (Christensen et al., 2005).

Patients received information regarding their diagnosis, and advice about adaptive illness behaviors and cautious use of painkillers. All consenting patients fulfilling the specific study criteria were invited to participate in the intervention.

2.3.2 Intervention: “Get going after concussion”

Originally, “Get going after concussion” was developed as an individually-tailored, multidisciplinary, manualized intervention programme, covering up to 8 weekly group sessions. Figure 1 illustrates the structure of the intervention in the first and second phase of the study, respectively. Table 1 presents the primary targets of the intervention and the corresponding intervention strategies. The objective of the intervention was to modify negative illness beliefs and maladaptive illness behaviours hypothesized to be associated with persistent PCS and thereby to break any vicious circles of excessive rest, or vicious circles of exertion and stress, to improve participation in daily activities and as a result to decrease symptom burden. All patients were encouraged to exercise regularly at an individually adjusted level. Each patient was allocated a therapist for the individual consultations.

Table 1
Overview of treatment elements in “Get going after concussion”. The different treatment elements may address several treatment targets simultaneously, and it is impossible in practise to separate cognitive and behavioural targets. For instance, maladaptive illness behaviors are expected to be indirectly altered through modification of negative illness perceptions. All educational topics are covered in the first and second group session. The information is delivered as powerpoint presentations with patient involvement through group discussions. In the individual sessions, the therapists may choose from the different intervention strategies depending on the individual patient’s goals and needs

Intervention target Intervention strategy

Negative illness perceptions:

Beliefs that symptoms Education on

•cannot be controlled. •concussion and transient PCS as part of the normal recovery process.

•are exclusively caused by the concussion. •persistent PCS in terms of the bio-psycho-social disease model: possible predisposing and perpetuating factors.

•are a sign of brain damage and will persist. Techniques derived from newer waves of cognitive behavioral therapy such as

•creating a distance to ones thoughts.

•exploring the relationship between thoughts and behavior.

•identifying individually important goals.

•refocusing on individually important goals instead of focusing on symptoms.

Maladaptive illness behaviour:

•Excessive rest Education on:

•Continuous physical or mental exertion •the negative effects of excessive rest, exertion and “all-or-nothing” behavior.

•the negative effects of fear-avoidance behavior.

•the negative effects of “pushing through symptoms” and how it may exacerbate PCS.

•the health-related benefits of exercise.

•“All-or-nothing” behaviour Balancing activity and rest at home, school, and / or work by:

•increasing or reducing daily activities¹.

•managing and prioritizing energy and resources, also including pleasurable activities.

•scheduling daily activities¹ and evening out activity level.

Gradual return to activities by:

•gradually increasing daily activities¹ and physical exercise in time and intensity from a level that do not/only temporarily exacerbate PCS, avoiding extreme oscillations.

•using a “pyramid of objectives” to work stepwise towards individually important goals.

Relaxation training.

•Deep-breathing exercise.

•Guided relaxation training (using a CD).

Specific techniques to facilitate more adaptive symptom management Counselling on:

•sleep habits and sleep hygiene.

•ergonomics and work habits.

•individually tailored neck exercises to reduce headache and/or neck pain focusing on neck flexor and extensor function.

•exposure exercises to reduce fear-avoidance behavior (i.e. related to dizziness or neck pain).

•cognitive difficulties (i.e. compensation training, cognitive remediation training).

•pain medication.

Intervention target	Intervention strategy
Negative illness perceptions:
Beliefs that symptoms	Education on
•cannot be controlled.	•concussion and transient PCS as part of the normal recovery process.
•are exclusively caused by the concussion.	•persistent PCS in terms of the bio-psycho-social disease model: possible predisposing and perpetuating factors.
•are a sign of brain damage and will persist.	Techniques derived from newer waves of cognitive behavioral therapy such as
	•creating a distance to ones thoughts.
	•exploring the relationship between thoughts and behavior.
	•identifying individually important goals.
	•refocusing on individually important goals instead of focusing on symptoms.
Maladaptive illness behaviour:
•Excessive rest	Education on:
•Continuous physical or mental exertion	•the negative effects of excessive rest, exertion and “all-or-nothing” behavior.
	•the negative effects of fear-avoidance behavior.
	•the negative effects of “pushing through symptoms” and how it may exacerbate PCS.
	•the health-related benefits of exercise.
•“All-or-nothing” behaviour	Balancing activity and rest at home, school, and / or work by:
	•increasing or reducing daily activities¹.
	•managing and prioritizing energy and resources, also including pleasurable activities.
	•scheduling daily activities¹ and evening out activity level.
Gradual return to activities by:
	•gradually increasing daily activities¹ and physical exercise in time and intensity from a level that do not/only temporarily exacerbate PCS, avoiding extreme oscillations.
	•using a “pyramid of objectives” to work stepwise towards individually important goals.
	Relaxation training.
	•Deep-breathing exercise.
	•Guided relaxation training (using a CD).
Specific techniques to facilitate more adaptive symptom management	Counselling on:
	•sleep habits and sleep hygiene.
	•ergonomics and work habits.
	•individually tailored neck exercises to reduce headache and/or neck pain focusing on neck flexor and extensor function.
	•exposure exercises to reduce fear-avoidance behavior (i.e. related to dizziness or neck pain).
	•cognitive difficulties (i.e. compensation training, cognitive remediation training).
	•pain medication.

¹Daily activities are broadly defined as everything we normally do in daily living including both physical and mental activities in work and education, leisure time, and personal care.

All treatment providers (2 occupational therapists, 1 physiotherapist and 1 neuropsychologist) had several years of clinical experience, including experience with neuro rehabilitation. Prior to the execution of the programme, the therapists received 2–5 days structured education in the management of symptom defined illnesses (Schröder & Dimsdale, 2014) and cognitive-behavioral principles. During the study period, they received regular supervision from psychiatrists specialized in CBT and with specific experience in CBT treatment of patients with symptom defined illnesses in order to ensure the quality of the intervention, the correct application of the CBT principles (Table 1), and the overall compliance with thetreatment manual.

To further monitor the therapists’ treatment fidelity, a self-report check-list covering the intervention strategies from Table 1 was developed to be completed by the therapists after each individual treatment session. The check-list was primarily developed to be applied in a future randomised controlled trial, and it was therefore not systematically applied in the feasibility study.

2.4 Measures

Patients filled out questionnaires at baseline and at the end of intervention (EOI), with follow-up (FU) at 3 and 12 months after the intervention.

Feasibility of the recruitment methods, recruitment rates and patients’ adherence to the treatment was evaluated after the first study phase based on the preliminary experiences.

Patients’ satisfaction was measured by 10 items from The Experience of Service Questionnaire (ESQ) (Barber, Tischler, & Healy, 2006). Patients reported their level of agreement with statements about facilities, staff and overall treatment satisfaction. To further evaluate feasibility, patient interviews using open-ended questions were performed after both the first and the second study phase.

Post-concussion symptoms were measured by The Rivermead Post-Concussion Symptoms Questionnaire (RPQ) (King et al., 1995). Respondents were asked to rate the degree to which 16 common PCS were more of a problem within the last 24 hours compared with pre-injury levels on a 5-point numerical rating scale from 0 (“not experienced at all”) to 4 (“a severe problem”)(range 0–64).

Health-Related Quality of Life (HRQoL) was measured by The Quality of Life after Brain Injury – Overall Scale (QOLIBRI-OS) (von Steinbuechel et al., 2012), a 6-item questionnaire measuring overall satisfaction with facets of life on a 5-point numerical rating scale from 1 (“not at all”) to 5 (“very”). The sum of all items was converted to a percentage scale (range 0 (worst)-100 (best)).

Illness perceptions were measured by The Brief Illness Perception Questionnaire (B-IPQ) (Broadbent, Petrie, Main, & Weinman, 2006) measuring core dimensions of illness perception using single items rated on a numerical scale from 0 to 10 to assess each dimension. The total score ranges from 0–70 with higher scores representing more negative perceptions of the concussion.

Illness behaviours were measured by The Behavioural Response to Illness Questionnaire (BRIQ) (Spence, Moss-Morris, & Chalder, 2005). Items were scored according to a frequency scale and coded from 1 (“not at all”) to 5 (“every day”). The two most important subscales were applied (Spence et al., 2005), i.e. “limiting behaviour”, corresponding to excessive rest, (7 items, range 7–35) and “all-or-nothing behaviour” (6 items,range 6–30).

Baseline anxiety and depression was measured by SCL-8, a subscale derived from Symptom Checklist Revised-90 measuring the risk of suffering from anxiety or depression (Fink et al., 2004). It consists of 8 items rated on a 5-point numerical rating scale from 1 (not at all) to 5 (extremely). Answers on single items were dichotomized between 0 (corresponding to a score of 0 or 1) and 1 (corresponding to a score of 3, 4 or 5) so that scores ranged from 0–8. A dichotomized score≥5 points corresponds to a 60% or more risk of suffering from anxiety or depression (Christensen et al., 2005).

2.5 Statistical analysis

Data on feasibility (recruitment methods, recruitment rates, adherence, follow-up rates, and patient satisfaction) were analysed descriptively. Changes in RPQ sum-scores, QOLIBRI-OS sum-scores and B-IPQ sum-scores as well as changes in two BRIQ subscale scores from baseline to 12-month FU were analysed using an unadjusted linear mixed model (one model for each of the above mentioned outcome measures) with time as the only (fixed effect) covariate and a random intercept. Using this model, we calculated the mean change from baseline to EOI, 3- and 12-month FU respectively as well as the Standardized Response Mean (SRM). All available data from all participants (including those who discontinued participation) were included in the analysis. The assumptions behind the mixed model were assessed using graphical inspection of the residuals and random intercepts. Stata version 13 for Windows was used for all statistical analyses.

3 Results

3.1 Participants

Figure 1 shows the flowchart of the study. In total, 32 patients were enrolled. Excluded patients showed a different distribution in gender than trial participants (46% vs. 81% females, p = 0.001). Table 2 shows baseline characteristics of participants. Twenty-eight percent had a substantial risk (60%) of suffering from anxiety or depression according to SCL-8. No patients suffered from PCS from potential earlier concussions at inclusion. Four of the included patients never attended the intervention, and one patient discontinued after the first session.Compared with the participants completing more than two sessions (n = 27, mean age 23.8, SD 4.7), these five patients were younger (mean age 20.8, SD 5.4), recruited from the cohort study only and mainly (four out of five) recruited during the first phase of the study where the intervention was group-based and less flexible than in the second phase (see below).

Table 2
Baseline demographics and clinical characteristics (N = 32)

Mean (range) or percentage (N)

Age (years) 23.3 (16.0–31.7)*

Employment status / educational status

- employed or students 63% (20)

- part-time or full-time sick leave 34 % (11)

- other 3 % (1)

Sex (female) 81% (26)

Previous health status

- previous concussion diagnosis within 2 years before inclusion 0 % (0)

- brain / neurological disorders (self-reported) 0 % (0)

- other chronic illness, not specified (self-reported) 8 % (2)

Recruitment

- cohort study 78 % (25)

- referred from GPs 22 % (7)

Mechanism of injury (self-reported)

- Motor vehicle accident 19 % (6)

- Traffic accident, bicycle or pedestrian 13 % (4)

- Traffic accident, not specified 6 % (2)

- Fall 26 % (8)

- Blow or jolt to the head 19 % (6)

- Sports injury 3 % (1)

- Assault 9 % (3)

- Unknown 6 % (2)

Time since injury at beginning of intervention (months) 5.2 (3.0–8.2)

Rivermead Post-concussion symptoms Questionnaire (sumscore, 0–64) 35 (19–52)*

Quality of Life after Brain Injury - Overall Scale (sumscore, 0–100) 39 (8–75)

Psychological distress: Symptom Checklist-8≥5 points 28 % (9)****

	Mean (range) or percentage (N)
Age (years)	23.3 (16.0–31.7)*
Employment status / educational status
- employed or students	63% (20)
- part-time or full-time sick leave	34 % (11)
- other	3 % (1)
Sex (female)	81% (26)
Previous health status
- previous concussion diagnosis within 2 years before inclusion	0 % (0)**
- brain / neurological disorders (self-reported)	0 % (0)**
- other chronic illness, not specified (self-reported)	8 % (2)**
Recruitment
- cohort study	78 % (25)
- referred from GPs	22 % (7)
Mechanism of injury (self-reported)
- Motor vehicle accident	19 % (6)
- Traffic accident, bicycle or pedestrian	13 % (4)
- Traffic accident, not specified	6 % (2)
- Fall	26 % (8)
- Blow or jolt to the head	19 % (6)
- Sports injury	3 % (1)
- Assault	9 % (3)
- Unknown	6 % (2)
Time since injury at beginning of intervention (months)	5.2 (3.0–8.2)
Rivermead Post-concussion symptoms Questionnaire (sumscore, 0–64)	35 (19–52)***
Quality of Life after Brain Injury - Overall Scale (sumscore, 0–100)	39 (8–75)
Psychological distress: Symptom Checklist-8≥5 points	28 % (9)****

*One patient was 31 at inclusion. **Data on previous health status was missing on 6 patients referred from GPs. Patients were asked about the following brain / neurological disorders: epilepsy, skull fracture, stroke, meningitis and brain tumor. Patients with serious chronic diseases were excluded at the clinical assessment. ***One patient with a score of 19 on the Rivermead Post-Concussion Symptoms Questionnaire was included based on a subjective overall impairment score of 8 (10-point numerical rating scale) at the beginning of the study. ****A sum-score≥5 points corresponds to a 60% or more risk of suffering from an emotional psychiatric disorder.

3.2 Feasibility findings and modifications

3.2.1 Recruitment methods and recruitment rates

The preliminary feasibility evaluation (in December 2014) resulted in modifications. Recruitment was slow and was therefore supplemented with referrals from GPs. Moreover, 61 patients recruited from the cohort study were scheduled for a clinical assessment, but 14 patients (23%) did not attend their appointment without cancelling. Accordingly, the recruitment procedures were modified so that potential participants were initially informed about the study by e-mail and invited to book an appointment. Non-responders were contacted by telephone. After these modifications, inclusion rates increased, and there was no absence from clinical assessments without cancellations.

3.2.2 Adherence, patient satisfaction and follow-up rates

In the first study phase, only five out of 14 included patients (36%) completed the intervention. The patient interviews revealed overall satisfaction with the content of the intervention, i.e. the education, the treatment elements (Table 1), the hand-out materials, the exchange with peers in the group and the individual training programme. However, we learned that (1) the group-based intervention often interfered with school, leisure time activities and/or work; (2) transportation was often a challenge; (3) two-hour sessions in the late afternoon were physically and cognitively demanding; (4) if possible, most participants would like the possibility of more flexible, individual consultations; and (5) some patients subjectively improved and therefore discontinued the intervention.

As a result, in the second study phase we changed the structure of the intervention to a combination of three “obligatory” group sessions and (depending on the patient’s needs) zero to five individual sessions (see Fig. 1). The individual sessions took place at flexible hours and could be delivered as face-to-face or video consultations at the patient’s choice. Hereafter, all patients received a consistent treatment dose (mainly psychoeducation) in the group sessions, while the individual sessions varied in treatment dose. The intervention strategies remained unchanged.

In the second study phase, 14 out of 18 included patients (78%) received four to five individual sessions, and no patient discontinued the intervention. Five patients (28%) used video consultations. The patient interviews after the second study phase revealed a high patient satisfaction with both the content and the modified structure of the early intervention.

Patients’ responses to the ESQ at EOI also demonstrated a high patient satisfaction. The majority reported that they were treated well by the therapists, they would recommend the intervention to a friend, and they felt that they had received good help (see Appendix, Fig. A1). The response rate improved considerably from EOI and 3-month FU (28% and 37% missings, respectively) to 12-month FU (19% missings).

3.3 Changes in symptoms, HRQoL, illness perceptions and illness behaviors

Figure 2 shows change following intervention in symptom level, HRQoL, illness perceptions, and illness behavior. There was a reduction of 8.9 points in mean RPQ score from baseline to EOI (95% CI 4.5 to 13.3, p < 0.001; SRM = 0.8, 95% CI 0.4 to 1.3). At the same time, QOLIBRI-OS sum score improved with 10.5 points (95% CI 2.5 to 18.5, p = 0.010; SRM = 0.4, 95% CI 0.1 to 0.7). Improvements in both PCS and in HRQoL were maintained at 3 and 12 months FU (all p < 0.01).

Fig.2

Change in post-concussion symptoms, quality of life, illness perceptions and illness behavior based on an unadjusted linear mixed model. The x-axis represents median time in months after concussion at the four assessment points (cf. Fig. 1). Baseline data from three patients were collected 2–4 weeks prior to the clinical assessment. Post-concussion symptoms = Rivermead Post-Concussion symptoms Questionnaire, total score (original scale); quality of life = The Quality of Life after Brain Injury - Overall Scale, total score (converted to a 0–100 scale); negative illness perceptions = The Brief Illness Perception Questionnaire, total score (converted to 0–100 scale); maladaptive illness behaviour = The Behavioural Response to Illness Questionnaire, “limiting behaviour” subscale score (converted to 0–100 scale). Asterisks indicate a statistically significant change from baseline to end of intervention, 3- and 12-month FU, respectively. *p < 0.05, **p < 0.01, ***p < 0.001.

B-IPQ total score decreased by 16.2 points (95% CI 9.7 to 22.7, p < 0.001) from baseline to EOI representing a less negative perception of the concussion, and this level was maintained at 3- and 12-month FU (p < 0.001). Table A1 (Appendix) shows changes on the 7 separate dimensions of the B-IPQ.

BRIQ “Limiting behavior” decreased by 13.9 points (95% CI 3.2 to 24.6, p = 0.011), and BRIQ “All-or-nothing behaviour” decreased by 9.5 points (95% CI 0.7 to 18.3, p = 0.035, data not shown) from baseline to EOI. Similarly, these levels were maintained at 3- and 12-month FU (all p < 0.05).

4 Discussion

The present study describes the development and feasibility of an early intervention for young people with persistent PCS and explores long-term changes in symptoms, impairment, illness perceptions and illness behaviors. We found that the recruitment, the assessment and the intervention procedures were feasible, and that the treatment satisfaction was high. Moreover we registered a considerable symptom reduction and HRQoL improvement after treatment, which was maintained up to 12 months after treatment and almost 2 years after the concussion. These changes were accompanied by changes towards more adaptive illness perceptions and illness behaviors.

4.1 Issues regarding recruitment methods and recruitment rates

We speculate whether the high non-attendance in the first study phase may have been due to a lack of motivation and realization of treatment needs. The successful change of recruitment procedures in the second study phase, where patients demonstrated motivation by booking an appointment for clinical assessment themselves, supports this assumption. By including patients referred from GPs in the second study phase, we increased the recruitment rates. We hypothesize that this may be due to the fact that many patients with concussion are never seen in hospitals (Cassidy et al., 2004).

4.2 Issues regarding adherence and patient satisfaction

Group sessions were initially chosen as the general format as they offer potential advantages in interventions for adolescents and young adults such as normalisation of symptoms, sharing of experiences and advice, and facilitation of treatment motivation (Pahl & Barrett, 2010). However, the first study phase revealed difficulties in the patients’ engagement in the full programme. Especially adolescents and young adults are known to be difficult to engage in treatment due to barriers such as failure to perceive long-term health consequences, lack of realization of treatment needs, discrepancies between advice from therapists and peer-condoned behaviors and activities, and failure of the intervention to appeal to the adolescents’ interests (Steinbeck, Baur, Cowell, & Pietrobelli, 2009). These barriers may also explain why the recruitment to the study was slower than expected.

The successful change from a group-based to an individualized treatment during the study increased patient engagement, which may be explained by the increased adjustment to individual needs and interests and the increased flexibility. This corresponds well to previous findings that patients with persistent PCS are a highly heterogeneous population with different treatment needs (McCrory et al., 2017; Potter & Brown, 2012).

4.3 The conceptual model underlying the intervention programme

Our promising results regarding changes after “Get going after concussion” are consistent with recent reviews of psychological treatments for persistent PCS (Al Sayegh et al., 2010; Potter & Brown, 2012; Snell et al., 2009). Furthermore, our findings are in line with the results of a recent randomised pilot study (N = 28) investigating the effect of 6 weekly, 50-minute CBT sessions delivered 6–12 weeks after concussion. The intervention was well tolerated and had a moderate effect on PCS (Silverberg et al., 2013).

Physical and cognitive rest until symptoms resolve has long been recommended after concussion, but previous randomised studies of strict rest in the acute phase after concussion in pediatric and adult populations have failed to demonstrate a benefit (Buckley, Munkasy, & Clouse, 2016; de Kruijk, Leffers, Meerhoff, Rutten, & Twijnstra, 2002; Eastman & Chang, 2015; Thomas, Apps, Hoffmann, McCrea, & Hammeke, 2015). There is increasing concern that complete rest beyond a few days may have negative physiological and psychological consequences (Schneider et al., 2013; Silverberg & Iverson, 2013; Winkler & Taylor, 2015). In fact, there is increasing evidence that patients with persistent PCS may benefit from physical exercise and gradual return to activities (Broshek et al., 2015; Chrisman et al., 2017; Junn et al., 2015; Maerlender, Rieman, Lichtenstein, & Condiracci, 2015; McCrory et al., 2013; Schneider et al., 2013; Silverberg & Iverson, 2013; Winkler & Taylor, 2015). The application of physical exercise and the treatment principle of gradual return to activities are in line with the most recent guidelines for managing concussion (DeMatteo et al., 2015; Marshall et al., 2015; McCrory et al., 2017), but more rigorous studies are needed to determine the optimal timing and amountsof exercise.

Research in chronic pain syndromes such as whiplash associated disorder and non-specific low back pain has identified similar cognitive and behavioural mechanisms involved in the development and maintenance of persistent symptoms (Boussard et al., 2014). Moreover, a combination of CBT and gradual increase in physical activity has proven effective for these syndromes (Hansen, Daykin, & Lamb, 2010; Sterling, 2014). These findings in other symptom-defined pain conditions support our conceptual model and treatment principles.

In the present study, the uncontrolled study design does not allow us to conclude if the reduction of PCS was an effect of the intervention or a result of spontaneous recovery. However, since average time since injury was 5.2 months prior to the intervention, we argue that the significant reduction in PCS after intervention is unlikely to be fully explained by spontaneous recovery, which usually diminishes 3 months after concussion or even earlier (Carroll et al., 2004; McCrory et al., 2017; Ponsford et al., 2012). To test the intervention’s effect, we are currently performing a randomised clinical trial.

4.4 Strengths and limitations

Our study has several strengths. Firstly, our recruitment procedures enhance the generalizability of our results, because we used relatively broad inclusion and exclusion criteria to ensure a clinically representative study sample, and we recruited both at-risk patients diagnosed with concussion in the hospital setting and referred from GPs thereby reducing selection bias. Secondly, all patients went through a thorough psychiatric and neurological assessment using standardized criteria for verifying the diagnosis, which is often lacking in concussion research (Kristman et al., 2014). Thirdly, we systematically designed a feasible, manualized, and theory-driven intervention building on current knowledge from the literature. Fourthly, all treatment providers received regular supervision.

Our study also has limitations. Firstly, we did not define clear a-priori criteria for assessing success of feasibility, which might have been beneficial for deciding on any further modifications of the protocol, e.g. to further increase recruitment rates. Secondly, patients’ compliance to the treatment manual were not systematically assessed, because we partly used the study to evaluate and adjust the manual and to develop fidelity procedures for the randomised controlled trial. Thirdly, because of the funding of the project, we faced the challenge of including a wide age range of both late teenagers and young adults (15–30 years). However, adolescence and young adulthood may be the most vulnerable time to have a concussion (McCrory et al., 2017), and therefore offering early treatment to this age group is important. Fourthly, we did not have access to previously recorded diagnoses, and thus we do not have detailed information on the participants’ pre-existing diagnoses. However, patients with severe co-morbid psychopathology or severe chronic illnesses were excluded at the clinical assessment. Of course, this exclusion at the same time potentially limits the generalizability of our findings.

4.5 Conclusions and implications

Overall, the results from the present study suggest that “Get going after concussion” is a feasible, pragmatic short-term intervention that may have the potential to reduce impairment, to prevent symptom chronification and to improve quality of life in young at-risk patients with persistent PCS. However, since this was an uncontrolled study, it is not possible to draw any conclusions about the efficacy of the intervention. An RCT testing the effect of the intervention is currently performed. If it proves clinically effective, a broader implementation of this new treatment program in a primary care or municipality setting may be feasible.

Conflict of interest

The authors have no financial interest to declare.

Funding

The Danish Foundation “Folkesundhed i Midten”.

Footnotes

Acknowledgement

We thank Inge Ris Hansen, University of Southern Denmark, for valuable input to the treatment protocol regarding neck exercises.

Appendix

Table A1

Change on seven dimensions of the Brief Illness Perceptions Questionnaire (B-IPQ)

Dimension on B-IPQ (0–10 scale)	Baseline Mean (95% CI)	EOI Mean (95% CI)	Change from baseline; p-value*	3 months’ FU Mean (95% CI)	Change from baseline; p-value*	12 months’ FU Mean (95% CI)	Change from baseline, p-value*
Consequences	7.7 (6.8–8.5)	5.9 (5.0–6.9)	p < 0.001	5.9 (4.9–6.9)	p < 0.001	5.5 (4.5–6.4)	p < 0.001
Timeline	5.9 (5.0–6.7)	5.4 (4.5–6.4)	p = 0.347	6.7 (5.7–7.6)	p = 0.120	6.2 (5.3–7.0)	p = 0.575
Personal control	7.1 (6.1–8.0)	5.2 (4.2–6.3)	p = 0.001	5.5 (4.5–6.5)	p = 0.003	4.4 (3.5–5.4)	p < 0.001
Treatment control	3.4 (2.6–4.3)	2.9 (1.8–3.9)	p = 0.387	3.6 (2.5–4.7)	p = 0.830	4.8 (3.9–5.8)	p = 0.028
Coherence	4.8 (3.9–5.7)	3.5 (2.5–4.6)	p = 0.034	3.7 (2.7 4.8)	p = 0.069	4.2 (3.2–5.2)	p = 0.299
Emotional representation	7.2 (6.2–8.1)	4.3 (3.2–5.4)	p < 0.001	5.8 (4.8–7.0)	p = 0.024	4.9 (3.9–5.9)	p < 0.001
Illness concern	8.1 (7.1–9.0)	4.8 (3.7–5.9)	p < 0.001	5.4 (4.4–6.5)	p < 0.001	4.9 (3.9–5.9)	p < 0.001

Change in illness perceptions from baseline to end of intervention, 3- and 12-month follow-up respectively. A higher score indicates a more negative illness perception on each dimension. *p-values are based on an unadjusted linear mixed model with time as fixed effect and a random intercept. p values in bold remain significant after Bonferroni correction for multiple testing (21 tests, critical p-value = 0.002). Abbreviations: CI = Confidence Interval; EOI = End of intervention; FU = follow-up.

References

Al Sayegh

, Sandford

, & Carson

A. J.

(2010). Psychological approaches to treatment of postconcussion syndrome: A systematic review. Journal of Neurology, Neurosurgery, and Psychiatry, 81(10), 1128–1134 doi: 10.1136/jnnp.2008.170092.

Ambrosini

P. J.

(2000). Historical development and present status of the schedule for affective disorders and schizophrenia for school-age children (K-SADS). Journal of the American Academy of Child & Adolescent Psychiatry, 39(1), 49–58 doi: 10.1097/00004583-200001000-00016.

Barber

A. J.

, Tischler

V. A.

, & Healy

(2006). Consumer satisfaction and child behaviour problems in child and adolescent mental health services. Journal of Child Health Care: For Professionals Working with Children in the Hospital and Community, 10(1), 9–21. doi: 10/1/9 [pii]

Boussard

C. N.

, Holm

L. W.

, Cancelliere

, Godbolt

A. K.

, Boyle

, Stalnacke

B. M.

, ߪ & Borg

(2014). Nonsurgical interventions after mild traumatic brain injury: A systematic review. Results of the international collaboration on mild traumatic brain injury prognosis. Archives of Physical Medicine and Rehabilitation, 95(3 suppl 2), 257–264. doi: 10.1016/j.apmr.2013.10.009.

Broadbent

, Petrie

K. J.

, Main

, & Weinman

(2006). The brief illness perception questionnaire. Journal of Psychosomatic Research, 60(6), 631–637.

Broshek

D. K.

, De Marco

A. P.

, & Freeman

J. R.

(2015). A review of post-concussion syndrome and psychological factors associated with concussion. Brain Injury, 29(2), 228–237. doi: 10.3109/02699052.2014.974674.

Buckley

T. A.

, Munkasy

B. A.

, & Clouse

B. P.

(2016). Acute cognitive and physical rest may not improve concussion recovery time. The Journal of Head Trauma Rehabilitation, 31(4), 233–241. doi: 10.1097/HTR.0000000000000165.

Carroll

L. J.

, Cassidy

J. D.

, Holm

, Kraus

, Coronado

V. G.

, & WHO

Collaborating Centre Task Force on Mild Traumatic Brain Injury.

(2004). Methodological issues and research recommendations for mild traumatic brain injury: The WHO collaborating centre task force on mild traumatic brain injury. (Suppl) 113–125.

Carroll

L. J.

, Cassidy

J. D.

, Peloso

P. M.

, Borg

, von Holst

, Holm

WHO Collaborating Centre Task Force on Mild Traumatic Brain Injury. (2004). Prognosis for mild traumatic brain injury: Results of the WHO collaborating centre task force on mild traumatic brain injury. (43 Suppl) 84–105.

10.

Cassidy

J. D.

, Carroll

L. J.

, Peloso

P. M.

, Borg

, von Holst

, Holm

WHO Collaborating Centre Task Force on Mild Traumatic Brain Injury. (2004). Incidence, risk factors and prevention of mild traumatic brain injury: Results of the WHO collaborating centre task force on mild traumatic brain injury. (43 Suppl) 28–60.

11.

Chrisman

S. P. D.

, Whitlock

K. B.

, Somers

, Burton

M. S.

, Herring

S. A.

, Rowhani-Rahbar

, & Rivara

F. P.

(2017). Pilot study of the sub-symptom threshold exercise program (SSTEP) for persistent concussion symptoms in youth. NeuroRehabilitation, 40(4), 493–499. doi: 10.3233/NRE-161436.

12.

Christensen

K. S.

, Fink

, Toft

, Frostholm

, Ørnbøl

, & Olesen

(2005). A brief case-finding questionnaire for common mental disorders: The CMDQ. Family Practice, 22(4), 448–457.

13.

de Kruijk

J. R.

, Leffers

, Meerhoff

, Rutten

, & Twijnstra

(2002). Effectiveness of bed rest after mild traumatic brain injury: A randomised trial of no versus six days of bed rest. Journal of Neurology, Neurosurgery, and Psychiatry, 73(2), 167–172.

14.

DeMatteo

, Stazyk

, Giglia

, Mahoney

, Singh

S. K.

, Hollenberg

, ߪ & Randall

(2015). A balanced protocol for return to school for children and youth following concussive injury. Clinical Pediatrics, 54(8), 783–792. doi: 10.1177/0009922814567305.

15.

Eastman

, & Chang

D. G.

(2015). Return to learn: A review of cognitive rest versus rehabilitation after sports concussion. NeuroRehabilitation, 37(2), 235–244. doi: 10.3233/NRE-151256.

16.

Fink

, Ornbol

, Huyse

F. J.

, De Jonge

, Lobo

, Herzog

, ߪ & Hansen

M. S.

(2004). A brief diagnostic screening instrument for mental disturbances in general medical wards. Journal of Psychosomatic Research, 57(1), 17–24. doi: 10.1016/S0022-3999(03)00374-X.

17.

Hansen

, Daykin

, & Lamb

S. E.

(2010). A cognitive-behavioural programme for the management of low back pain in primary care: A description and justification of the intervention used in the back skills training trial (BeST; ISRCTN. Physiotherapy, 96(2), 87–94. doi: 10.1016/j.physio.2009.09.008.

18.

Holm

, Cassidy

J. D.

, Carroll

L. J.

, Borg

, Neurotrauma Task Force on Mild Traumatic Brain Injury of the WHO Collaborating Centre. (2005). Summary of the WHO collaborating centre for neurotrauma task force on mild traumatic brain injury. Journal of Rehabilitation Medicine, 37(3), 137–141. doi: T3271633283336R1 [pii].

19.

Hou

, Moss-Morris

, Peveler

, Mogg

, Bradley

B. P.

, & Belli

(2012). When a minor head injury results in enduring symptoms: A prospective investigation of risk factors for postconcussional syndrome after mild traumatic brain injury. Journal of Neurology, Neurosurgery, and Psychiatry, 83(2), 217–223. doi: 10.1136/jnnp-2011-300767.

20.

Iverson

G. L.

(2005). Outcome from mild traumatic brain injury. Current Opinion in Psychiatry, 18(3), 301–317. doi: 10.1097/01.yco.0000165601.29047.ae.

21.

Junn

, Bell

K. R.

, Shenouda

, & Hoffman

J. M.

(2015). Symptoms of concussion and comorbid disorders. Current Pain and Headache Reports, 19(9), 46. doi: 10.1007/s11916-015-0519-7.

22.

King

N. S.

(2003). Post-concussion syndrome: Clarity amid the controversy? The British Journal of Psychiatry: The Journal of Mental Science, 183, 276–278.

23.

King

N. S.

, Crawford

, Wenden

F. J.

, Moss

N. E.

, & Wade

D. T.

(1995). The rivermead post concussion symptoms questionnaire: A measure of symptoms commonly experienced after head injury and its reliability. Journal of Neurology, 242(9), 587–592.

24.

Kristman

V. L.

, Borg

, Godbolt

A. K.

, Salmi

L. R.

, Cancelliere

, Carroll

L. J.

, ߪ & Cassidy

J. D.

(2014). Methodological issues and research recommendations for prognosis after mild traumatic brain injury: Results of the international collaboration on mild traumatic brain injury prognosis. Archives of Physical Medicine and Rehabilitation, 95(3 Suppl), 265–277. doi: 10.1016/j.apmr.2013.04.026.

25.

Maerlender

, Rieman

, Lichtenstein

, & Condiracci

(2015). Programmed physical exertion in recovery from sports-related concussion: A randomized pilot study. Developmental Neuropsychology, 40(5), 273–278. doi: 10.1080/87565641.2015.1067706.

26.

Marshall

, Bayley

, McCullagh

, Velikonja

, Berrigan

, Ouchterlony

, & Weegar

(2015). Updated clinical practice guidelines for concussion/mild traumatic brain injury and persistent symptoms. Brain Injury, 29(6), 688–700. doi: 10.3109/02699052.2015.1004755.

27.

McCrea

, Iverson

G. L.

, McAllister

T. W.

, Hammeke

T. A.

, Powell

M. R.

, Barr

W. B.

, & Kelly

J. P.

(2009). An integrated review of recovery after mild traumatic brain injury (MTBI): Implications for clinical management. The Clinical Neuropsychologist, 23(8), 1368–1390. doi: 10.1080/13854040903074652.

28.

McCrory

, Meeuwisse

, Aubry

, Cantu

, Dvorak

, Echemendia

, ߪ & Turner

(2013) Consensus statement on concussion in sport - the 4th international conference on concussion in sport held in Zurich, november 2012. Physical Therapy in Sport: Official Journal of the Association of Chartered Physiotherapists in Sports Medicine, 14(2), e1–e13. doi: 10.1016/j.pts2013.03.002.

29.

McCrory

, Meeuwisse

, Dvorak

, Aubry

, Bailes

, Broglio

, ߪ & Vos

P. E.

(2017) Consensus statement on concussion in sport-the 5th international conference on concussion in sport held in Berlin, october 2016, British Journal of Sports Medicine. doi: bjsports-2017-097699 [pii].

30.

Pahl

K. M.

, & Barrett

P. M.

(2010). Interventions for anxiety disorders in children using group cognitive-behavioural therapy with family involvement. In Weisz

J. R.

, & Kazdin

A. E.

(Eds.), Evidence-based psychotherapies for children and adolescents (2nd ed., Chapter 3). New York, US: Guilford Press.

31.

Ponsford

(2005). Rehabilitation interventions after mild head injury. Current Opinion in Neurology, 18(6), 692–697. doi: 00019052-200512000-00012 [pii].

32.

Ponsford

, Cameron

, Fitzgerald

, Grant

, Mikocka-Walus

, & Schonberger

(2012). Predictors of postconcussive symptoms months after mild traumatic brain injury. Neuropsychology, 26(3), 304–313. doi: 10.1037/a0027888.

33.

Potter

, & Brown

R. G.

(2012). Cognitive behaviour therapy and persistent post-concussional symptoms: Integrating conceptual issues and practical aspects in treatment. Neuropsychological Rehabilitation, 22(1), 1–25. doi: 10.1080/09602011.2011.630883.

34.

Prigatano

G. P.

, & Gale

S. D.

(2011). The current status of postconcussion syndrome. Current Opinion in Psychiatry, 24(3), 243–250. doi: 10.1097/YCO.0b013e328344698b.

35.

Ruff

R. M.

(2011). Mild traumatic brain injury and neural recovery: Rethinking the debate. NeuroRehabilitation, 28(3), 167–180. doi: 10.3233/NRE-2011-0646.

36.

Samwel

H. J.

, Kraaimaat

F. W.

, Crul

B. J.

, & Evers

A. W.

(2007). The role of fear-avoidance and helplessness in explaining functional disability in chronic pain: A prospective study. International Journal of behaviour Medicine, 14(4), 237–241. doi: 10.1080/10705500701638443.

37.

Schneider

K. J.

, Iverson

G. L.

, Emery

C. A.

, McCrory

, Herring

S. A.

, & Meeuwisse

W. H.

(2013). The effects of rest and treatment following sport-related concussion: A systematic review of the literature. British Journal of Sports Medicine, 47(5), 304–307. doi: 10.1136/bjsports-2013-092190.

38.

Schröder

, & Dimsdale

(2014). Management of somatic symptoms. Scientific American Medicine, 4, 1–21. doi: 10.2310/7900.1300.

39.

Silverberg

N. D.

, Hallam

B. J.

, Rose

, Underwood

, Whitfield

, Thornton

A. E.

, & Whittal

M. L.

(2013). Cognitive-behaviour prevention of postconcussion syndrome in at-risk patients: A pilot randomized controlled trial. The Journal of Head Trauma Rehabilitation, 28(4), 313–322. doi: 10.1097/HTR.0b013e3182915cb5.

40.

Silverberg

N. D.

, & Iverson

G. L.

(2011). Etiology of the post-concussion syndrome: Physiogenesis and psychogenesis revisited. NeuroRehabilitation, 29(4), 317–329. doi: 10.3233/NRE-2011-0708.

41.

Silverberg

N. D.

, & Iverson

G. L.

(2013). Is rest after concussion “the best medicine?”: Recommendations for activity resumption following concussion in athletes, civilians, and military service members. The Journal of Head Trauma Rehabilitation, 28(4), 250–259. doi: 10.1097/HTR.0b013e31825ad658.

42.

Snell

D. L.

, Hay-Smith

E. J.

, Surgenor

L. J.

, & Siegert

R. J.

(2013). Examination of outcome after mild traumatic brain injury: The contribution of injury beliefs and Leventhal’s common sense model. Neuropsychological Rehabilitation, 23(3), 333–362. doi: 10.1080/09658211.2012.758419.

43.

Snell

D. L.

, Surgenor

L. J.

, Hay-Smith

E. J.

, & Siegert

R. J.

(2009). A systematic review of psychological treatments for mild traumatic brain injury: An update on the evidence. Journal of Clinical and Experimental Neuropsychology, 31(1), 20–38. doi: 10.1080/13803390801978849.

44.

Spence

, Moss-Morris

, & Chalder

(2005). The behaviour responses to illness questionnaire (BRIQ): A new predictive measure of medically unexplained symptoms following acute infection. Psychological Medicine, 35(4), 583–593.

45.

Steinbeck

, Baur

, Cowell

, & Pietrobelli

(2009). Clinical research in adolescents: Challenges and opportunities using obesity as a model. International Journal of Obesity (2005), 33(1), 2–7. doi: 10.1038/ijo.2008.263.

46.

Sterling

(2014). Physiotherapy management of whiplash-associated disorders (WAD. Journal of Physiotherapy, 60(1), 5–12. doi: 10.1016/j.jphys.2013.12.004.

47.

Stulemeijer

, van der Werf

, Borm

G. F.

, & Vos

P. E.

(2008). Early prediction of favourable recovery months after mild traumatic brain injury. Journal of Neurology, Neurosurgery, and Psychiatry, 79(8), 936–942. doi: jnn2007.131250 [pii].

48.

Thomas

D. G.

, Apps

J. N.

, Hoffmann

R. G.

, McCrea

, & Hammeke

(2015). Benefits of strict rest after acute concussion: A randomized controlled trial. Pediatrics, 135(2), 213–223. doi: 10.1542/peds.2014-0966.

49.

von Steinbuechel

, Wilson

, Gibbons

, Muehlan

, Schmidt

, ߪ & Truelle

J. L.

(2012). QOLIBRI overall scale: A brief index of health-related quality of life after traumatic brain injury. Journal of Neurology, Neurosurgery, and Psychiatry, 83(11), 1041–1047. doi: 10.1136/jnnp-2012-302361.

50.

Whittaker

, Kemp

, & House

(2007). Illness perceptions and outcome in mild head injury: A longitudinal study. Journal of Neurology, Neurosurgery, and Psychiatry, 78(6), 644–646. doi: 78/6/644 [pii].

51.

Williams

W. H.

, Potter

, & Ryland

(2010). Mild traumatic brain injury and postconcussion syndrome: A neuropsychological perspective. Journal of Neurology, Neurosurgery, and Psychiatry, 81(10), 1116–1122. doi: 10.1136/jnn2008.171298.

52.

Wing

J. K.

, Babor

, Brugha

, Burke

, Cooper

J. E.

, Giel

, ߪ & Sartorius

(1990). SCAN. schedules for clinical assessment in neuropsychiatry. Archives of General Psychiatry, 47(6), 589–593.

53.

Winkler

, & Taylor

N. F.

(2015). Do children and adolescents with mild traumatic brain injury and persistent symptoms benefit from treatment? A systematic review. The Journal of Head Trauma Rehabilitation, 30(5), 324–333. doi: 10.1097/HTR.0000000000000114.