Study design
The study is a prospective assessor-blinded block-randomised controlled trial, with a parallel group-design, with a 6- and 12-months follow-up. The protocol conforms with the recommendations from the EQUATOR network (28), using the Standard Protocol Items: Recommendations for Interventional Trails (SPIRIT) checklist and the Consolidated Standard of Reporting Trials (CONSORT) guidelines when reporting the results (29,30). The SPIRIT checklist is available in additional file 1.
Settings and location
Participants will be recruited through general practitioners, physiotherapists, Ear-Nose and Throat specialists, and information through newspapers and the social media. Participants will be recruited from the region in and around Bergen, Norway. Blinded baseline and follow-up testing and one-session VR intervention (BI-VR) will be conducted at the Western Norway University of Applied Sciences (HVL). Group treatment (VR-CBT) will be offered at HVL, as well as at selected physiotherapy clinics in Bergen. The group treatment will be led by physiotherapists trained in the treatment protocol (please see below).
Participants
Eligible participants must meet all the following inclusion criteria: Working age (18-70 years) with acute onset of dizziness and with symptoms lasting at least 3 months, and the dizziness has to be triggered/ worsened by head movements,
Participants will be excluded if they meet one or more of the following exclusion criteria: self-reported non-vestibular reason for dizziness (e.g. neurological conditions) or fluctuating vestibular diseases (e.g. Ménière’s disease), scheduled for treatment of/ have had treatment for benign paroxysmal positional vertigo (BPPV) within one month, fast head movements are contraindicated (e.g. whiplash associated injuries, osteoporosis of the neck ), presentation of severe/ terminal pathology (cancer, psychiatric diagnosis), participated in group-therapy for dizziness within the past year, inadequate Norwegian language proficiency (verbal and written), or unable to attend test and treatment locations.
Procedure
Eligible participants will initially be screened by a telephone interview followed by further screening at HVL. Participants fulfilling the inclusion and exclusion criteria who are willing to participate will be asked to sign an informed consent (supplementary material, in Norwegian). The first meeting comprises screening by the assessors, signing of informed consent, and baseline testing. This is scheduled to last two hours. During baseline testing the included participants will complete physical tests and questionnaires. Following baseline testing the participants attend a one-hour treatment session (BI-VR), and afterwards randomisation to either the intervention group or the control group. Follow-up testing are scheduled 6 and 12 months after inclusion (Table. 1) comprising online or paper versions of questionnaires (completed separately from testing) and objective outcomes. Both follow-up tests are scheduled to last up to one hour.
Table 1. Spirit figure of study protocol
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STUDY PERIOD
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Enrolment
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Post allocation
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Timepoint
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Month 0-2
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Month 1-6
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6 months
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12 months
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ENROLMENT
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Eligibility screen
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X
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Informed consent
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X
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Allocation
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X
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INTERVENTIONS
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BI-VR
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X
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VR-CBT
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X
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ASSESSMENTS
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Dizziness Handicap Inventory
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X
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X
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X
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Preferred gait velocity
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X
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X
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X
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Vertigo Symptom scale- Short form
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X
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X
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X
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Body Sensation Questionnaire
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X
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X
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X
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Adapted Panic attack Scale
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X
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X
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X
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Mobility Index, Alone
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X
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X
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X
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Panic attack scale
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X
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X
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X
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Patient Specific function questionnaire
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X
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X
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X
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Subjective Health complaints
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X
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X
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X
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Patient global impression of change
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X
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X
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Chalders fatigue questionnaire
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X
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X
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X
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EQ5D-5L
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X
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X
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X
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Body sway in standing
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X
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X
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X
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Head movement induced dizziness
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X
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X
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X
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Fast gait velocity
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X
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X
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X
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Clinical dynamic visual acuity
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X
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X
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X
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Elements from GPE
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X
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X
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X
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Dual task walking
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X
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X
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X
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Grip strength
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X
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X
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x
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Interventions
Brief Intervention Vestibular Rehabilitation (BI-VR)
All the participants receive Brief Intervention Vestibular Rehabilitation (BI-VR), a single-session treatment based on elements from traditional VR (31,32), but adapted to a single session in line with a brief intervention model developed for patients with low back pain (33). The purpose of the treatment is to give the participant the understanding that movement is the key factor in improving symptoms and that dizziness rarely is related to serious illness. BI-VR comprises examination, information regarding the vestibular system, what causes dizziness, advice related to specific findings, and supervision in selected standardised VR exercises. All participants are encouraged to stay active, and provoke dizziness in line with established recommendations (14, 34).
Control group
Participants allocated to BI-VR only, will be encouraged to do the prescribed exercises on their own. The BI-VR physiotherapist will call twice during a four-month period, to encourage compliance with the home-exercises and answer questions that may arise.
Intervention group
Vestibular Rehabilitation and Cognitive Behavioural Therapy (VR-CBT).
Participants in the intervention group will be invited to attend an additional structured group-treatment program integrating vestibular rehabilitation and cognitive behaviour therapy (VR-CBT). The VR-CBT manual was developed through collaboration between researchers, physiotherapists and clinical psychologists. The treatment offers eight weekly two-hour sessions with five to eight participants in each group, with the aim of addressing both the physical and psychological challenges of persistent dizziness. The CBT approach is based on previous findings indicating that treatment for panic disorders can also be efficacious for persons with chronic dizziness (20). CBT focuses on the vicious cycle between somatic anxiety symptoms elicited by the “fight or flight” response, the catastrophic misinterpretations of these and other bodily symptoms, and the resulting safety- and avoidance behaviour (35). The VR comprises habituation, gaze stability and balance exercises, with body awareness promoted throughout, in addition to guided relaxation (34, 36). The exercises may be individually adapted, by for instance adjustments in base of support, speed of movement, and environmental conditions. All sessions will have elements of both VR and CBT, however, the first three sessions mostly emphasise CBT, while the subsequent five sessions mostly emphasise VR. This set up allows the participants to practise exercises in a safe environment, and provides opportunities to reflect on dizziness, safety and avoidance behaviours that may occur. Participants are further asked to carry out and register home exercises following the treatment sessions, and daily VR exercises are introduced from session three onwards. A brief description of the VR-CBT manual is presented in Table 2.
Table 2. Brief description of the Vestibular Rehabilitation – Cognitive behaviour therapy (VR-CBT) group treatment protocol
Session
nr
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Focus
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Example of tasks/ exercises
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1
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Dizziness and additional/ secondary complaints
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Discussion on dizziness and additional complaints.
Introducing the vicious circle that can arise between somatic symptoms and the catastrophic misinterpretation of these. Exercises: Body awareness in sitting and standing. Habituation (nodding and head turns)
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2
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The “vicious circle”
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How somatic symptoms related to both dizziness and anxiety can be appraised appropriately, by mapping the relevant symptoms, thoughts, and potential avoidance behaviour for each participant. Introducing the “fight or flight” response, and how this may be relevant for chronic dizziness.
Exercises: Body awareness in standing and walking, habituation through games with planned and unplanned head turns.
Relaxation.
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3
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The “fight or flight- response”
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Discussion regarding experiences related to symptoms similar to the fight or flight response. How can these symptoms be appraised in relation to persistent dizziness.
Exercises: Habituation and body awareness (standing balance, walking with directional changes). Reflection during and after exercises. What happened? What was your response? (every session from now)
Relaxation.
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4
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The fight or flight response and management.
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Discussion: How did you respond to the fight or flight response in every-day life following the last session? Individual goal setting.
Exercises: Habituation, visual acuity, walking and ball games with change of place, turning and rotation.
Relaxation
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5
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Relaxation
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Discussion/ reflection: Exercises, dosage and “relaxation”. It is normal to be dizzy and tired after exercises
Exercises: Progression of visual acuity, habituation and balance using ball during exercise. Working alone and in pairs.
Relaxation
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6
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Movement induced dizziness
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Any changes in relation to the dizziness circle described in first session? Group and individual reflection.
Exercises: Habituation games: in larger groups and pairs. Walking with head rotations, velocity changes, and externally induced stop/start.
Relaxation
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7
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What next? Preparation for the future
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Discussion before, reflection during and group reflection after exercises: “How do I cope/ deal/ manage the dizziness. What thoughts are formed when I get dizzy?”
Exercises: Combination of balance and habituation – Activities and games in groups and in pairs. (e.g. obstacle course, standing back to back, passing ball at different heights.)
Relaxation
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8
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Reflection and conclusion
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Discussion: “What have I learnt? What will I take with me? What do I do when/if dizziness returns?”
Exercises: Balance and body awareness in standing and walking, changing directions, different velocities, stop/start. Ball activities alone, in pairs and in larger group
Relaxation
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Physiotherapists
One physiotherapist experienced in VR, and trained in the BI-VR protocol, will run all BI-VR sessions. Six physiotherapists delivering the VR-CBT treatment will attend a competency course to before leading the treatment. The competency course contains the principles of VR-CBT, the elements of the treatment manual, and training of practical skills related to the manual, as described in the feasibility study (27). After each of the first two treatment sessions a clinical psychologist and the principal investigator will be available for support and guidance, without unblinding participant allocation.
Data collection and follow up
Three assessors (principal investigator, project lead, and one research assistant) are involved in collecting informed consent, and blinded data collection at baseline and follow up, adhering to the standardised test protocol. In addition, the assessors will practise together before and during data collection, in order to unify performance and interpretation of the outcome measures. The principal investigator will perform the majority of the data collection.
Personal information related to the participants will be stored on a secure server only accessible to the researchers involved in the research projects. Outcomes collected on paper will be registered into a secure file and placed on the same server, and paper copies will be kept in a locked cupboard only accessible by the principle investigator. After completion of the project all paper copies will be destroyed, and the dataset will be anonymised.
Outcome measures
Table 3 describes the outcomes that will be collected at the various stages in the study.
Primary outcome measures
The primary outcome measures are the Dizziness Handicap Inventory (DHI) and preferred gait velocity. The DHI is a questionnaire developed in order to assess the impact of dizziness on quality of life (37). It is translated into Norwegian and has shown satisfactory test-retest reliability (38). Preferred gait velocity is assessed using 6-meter timed gait test, with one additional meter at each end allowing acceleration and deceleration (39). The test has been found reliable in healthy adults (40), as well as in persons with vestibular disorders (39).
Secondary outcome measures
The secondary outcomes include dizziness severity, psychological complaints, fatigue, subjective health complaints, standing balance, walking, strength, flexibility, and general quality of life.
The patient reported outcomes is used to evaluate dizziness severity using the Norwegian version (41) of the Vertigo Symptom Scale short form (VSS) (42). In addition, the Hospital Anxiety and Depression Questionnaire (HADS) (43), the Body Sensations Questionnaire (BSQ) (44), the Agoraphobic Cognition Questionnaire (ACQ) (44), the Mobility Inventory of Agoraphobia- Alone (MIA) (45), and an adapted version of the Panic Attack Scale (PAS) (46) describes levels of anxiety, depression, panic-related symptoms, and avoidance behaviour. Further, fatigue is assessed using the Chalder’s Fatigue questionnaire (CFQ) (47), while the subjective health complaint inventory (SHC) reports incidents and extent of subjective somatic and psychological complaints (48). Patient Specific Functional Scale (PSFS) assesses perceived functional change (49), while information regarding quality of life is gathered using the EQ5D-5L (50).
Secondary objective measures include standing balance (sway measured during the four conditions in the modified clinical test for sensory interaction and balance (mCTSIB)) (51) using balance trainer BTG4 (HUR health, Norway), walking (fast velocity and with dual task (52)), visual acuity (clinical dynamic visual acuity test (CDVA) (53)), and grip strength (54). Musculoskeletal aberrations is registered using four elements from the Global Physiotherapy Examination (GPE) (17) and Head movement induced dizziness (39) measured using the numeric rating scale (HmDizz). The Patient Global Impression of Change questionnaire (PGIC) (55) is used to evaluate perceived improvement at follow-up testing at 6 and 12 months
Table 3. Description and test metrics of outcome measures
Name
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Scoring/ description
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Test metrics
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Primary outcome measures
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Dizziness Handicap inventory (DHI)
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25 items, each item has three alternative scores 0 (no), 2 (sometimes), and 4 (yes) giving a score-range of 0-100 DHI points (37). Higher scores indicate greater perceived disability; 0-30; mild, 31-60; moderate, 61-100; severe (60).
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Cut-off 29 points,
MIC 11 DHI points,
ICC 1,1 0.90 (38).
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Preferred gait velocity (m/sec)
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Participants walked at normal pace, down an 8m pathway, timed in the middle 6m. It was timed using a stopwatch from when the first foot passed the start point to when the last foot passed the stop point.
Mean velocity over two trials were calculated.
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Substantial meaningful change 0.1 m/s (61),
ICC (3.1): 0.88 (CI 0.81-0.98) (39)
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Secondary outcomes /Patient reported outcomes
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The shortened version of the Vertigo Symptom Scale (VSS)
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15 items, each scoring from 0 (never)
to 4 (very often) giving a score range of 0-60. Higher scores indicate higher symptom severity (42). Severe dizziness: ≥ 12 (42).
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Norwegian version cut-off 6.5 points (41).
Clinical significant change in original version ≥ 3 points (62).
ICC Norwegian version: 0.89 (41).
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Agoraphobic Cognitions Questionnaire (ACQ)
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14 items, each rated on a scale ranging from 1 (thought never occurs when I am nervous) to 5 (thought always occurs when I am nervous) (44). Measures fear of fear.
Mean score is reported, and higher scores imply greater levels of fear.
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Chronbach’s alpha for outpatients with agoraphobia: 0.80 (44)
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Body Sensation Questionnaire (BSC)
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18 items, each with a score range from
1 (not at all frightened by the sensations) to 5 (extremely frightened by this sensation). The mean score reported, and higher scores implies greater fear of somatic sensations (44).
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Chronbach’s alpha for outpatients with agoraphobia 0.87 (44).
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Mobility Inventory of Agoraphobia, Alone (MIA)
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27 items, each rated from 1 (never avoids) to 5 (always avoids). Mean score is reported and, and higher scores indicated greater avoidance behaviour.
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Chronbach’s alpha in agoraphobia: 0.96 (45)
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Adapted Panic Attack Scale
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- Attack frequency
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Measures frequency of distress related to sudden onsets of episodes with four or more strong sensations of dizziness and dizziness related symptoms on a five point scale ranging from 0 (no attacks) to 4 (one or more attacks per day). Adapted from the Panic Attack Scale (46)
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- Attack severity
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Severity rating of the degree of distress related to the episodes described above. Numeric rating scale with a score range 0-8. Higher score indicates increased symptom related distress/ disability. Adapted from the Panic Attack Scale (46)
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Hospital Anxiety and Depression Scale (HADS)
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14 items, each rated from 0 (not present) to 3 (considerable), giving a score range of 0-42 points (43). Higher score indicates greater psychological distress.
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Cut-off 12 points,
Chronbach’s alpha: 0.88. (63).
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EQ5D-5L
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Generic instrument describing and valuing health (64).
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- EQ5D-5L
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Five dimensions, each rated from 1 to 5. Higher scores indicate increased problems health (65).
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- EQ5D-5L Vas
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Score range 0-100 %. Higher scores indicate better perceived health related quality of life.
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MCID in stroke: 8.61-10.82 (66).
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Subjective Health Complaints (SHC)
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29 items, each item is scored from 0 (no complaints) to 3 (serious complaints). Higher scores indicate higher severity of complaint. Split into 5 subcategories: Musculoskeletal 8 items (score 0-24), Pseudoneurology 7 items (score 0-21), Gastrointestinal 7 items (score 0-21), Flu 2 items (score 0-6), and Allergy 5 items (score 0-15) (67).
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Chronbach’s alpha musculoskeletal pain: 0.74,
Pseudoneurology: 0.73,
Gastrointenstinal: 0.62,
Allergy: 0.58, and
Flu: 0.67 (67).
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Chalder’s Fatigue Questionnaire (CFQ)
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13 items. The first 11 items are scored from 0 (better than usual) to 3 (much worse than usual), giving a score range of 0-33. The last two items rates duration and constancy of fatigue (47). Higher scores indicating more fatigued.
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Chronbach’s alpha in Norwegian population: 0.86 (68).
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Patient Specific Functional Scale (PSFS)
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Registers up to 3 activities participants find difficult. In addition the level of difficulty is rated on an 11 point scale (49), where 0 maximum difficulty and 10 is no difficulty.
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Reliability established in various musculoskeletal problems (ICC: 0.76- 0.97) (69)
MCID in various musculoskeletal problems: 0.99-2.5 (69)
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Patient Global Impression of Change (PCIG)
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1Item, rated from 1 (very much improved) to 7 (very much worse), with a score of 4 indicating no change (55).
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Secondary outcomes/ Physical tests
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Dual-Task walking
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Similar walking protocol as for preferred gait velocity, with an added task of counting backwards by three out loud, while walking. Each trial was timed and the numbers of miscounts were documented. Mean velocity, and mistakes over two trials calculated.
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Fast gait velocity (m/s)
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Similar protocol to preferred gait velocity, however, participants were asked to walk as fast as possible.
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Clinical dynamic visual acuity (CDVA)
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Evaluates gaze stability by assessing visual acuity using examiner mediated head oscillations at 2Hz relative to head stationary.
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Cut-off ≥ 3 lines indicates potential vestibular hypofunction (53). Reliability in bilateral peripheral hypofunction ICC(2.2): 0.94 (70).
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Head movement induced dizziness
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Perceived dizziness reported using the Numeric Rating Scale (NRS) on two conditions. One while sitting stationary, and one after 1 minute of active head oscillations at 1 Hz (following a metronome). Score range 0 (no dizziness) to 10 (as bad as it can be), with higher scores indicating higher perceived intensity of head movement-induced dizziness. Difference between the two conditions will also be calculated.
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Reliability of male subjects 0.82
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Grip strength
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Maximal grip strength in both hands assessed using hand-held dynamometer. Measured in kg. Averaged between two trials calculated for each hand
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Genuine change in healthy adults; 6kg (71).
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Body sway in standing
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Assessed using the Modified test for interaction and balance (mCTSIB) with arms crossed over the chest, using the HURlabs Balance trainer BTG4. Four conditions tested, standing with eyes open and closed, on a firm surface or on a foam cushion. Each trial is timed for 30 seconds.
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ICC in healthy subjects: 0.91-0.97 (72).
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Elements from Global Physiotherapy Examination (GPE)
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Four elements from the main domain Movement of the GPE examination were selected (17, 36). The items include lumbo-sacral flexion, head-nod flexion, shoulder retraction and elbow drop.
Score range -2.3 to 2.3, scored in relation to a predefined standard (0) (36).
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ICC 2.1 Lumbro-sacral flexion: 0.82,
ICC 2.1 Head nod-flexion: 0.84,
ICC2.1 Shoulder retraction: 0.75,
ICC 2.1 Elbow drop: 0.89 (Personal communication: A. Kvåle).
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Demographic data and other measurements
In addition to the outcomes, information regarding gender, age, work status, medication, and activity level will be gathered. The VR-CBT physiotherapists will register attendance to sessions and reasons for absence and collect the home-exercise registrations.
Satisfactory compliance to VR-CBT will be defined as minimum 75% attendance to VR-CBT sessions (6/8 sessions), and minimum 80% completion of the exercise diary for home-exercises, where 100% completion is defined by reporting exercises and following a walking program five times per week. Satisfactory compliance in the control-group will be defined as completion of at least one telephone call with the BI-VR physiotherapist.
Sample size and power considerations
The study is designed as a randomised controlled trial comparing two groups (BI-VR, and BI-VR with VR-CBT). To obtain a clinical important group difference in DHI of 11 points (38) with a significance level of 0.05 and a power of 80%, 47 participants will be required per group. To obtain a clinical important change in preferred gait velocity of 0.1 m/s (56) with a significance level of 0.05 and a power of 80%, 36 participants will be required in each group. In order to ensure power of both primary outcomes at least 47 participants are selected as basis for the sample size needed in the study. The final sample size is set at 125 participants, allowing for approximately 35% drop-out, based on drop-outs in the feasibility study (27), and in previous studies (18, 20, 57,58).
Randomization and concealment of allocation
The participants are block-randomised in groups of 16, and randomly assigned to BI-VR followed by VR-CBT (intervention group) or BI-VR alone (control group). Group allocation is performed using a random number generator and is presented on a folded paper, in a concealed envelope. The principle investigator is blinded from group allocations. The envelopes are stored in a locked cupboard only accessible to the BI-VR physiotherapist handing out the allocation envelopes. After group allocation the VR-CBT participants will be contacted by the project lead regarding the first VR-CBT appointment.
Blinding
The principal investigator and assessors are blinded from group allocation and not involved in the treatment of the participants. Blinding of group allocation for VR-CBT physiotherapists and participants are not possible. However, both groups are informed that the optimal treatment is not known, and the study hypothesis is not presented. In order to ensure blinding of assessors the participants are encouraged not to reveal their allocation during testing.
Statistical analysis plan
The efficacy analysis is assessment of the between-group differences in changes in DHI score and preferred gait velocity at 6 and 12 months follow up. The analysis will use the intention to treat (ITT) principle, analysing all randomised participants independent of compliance and withdrawals. In the event of missing data two methods will be used. For missing single questions, the mean baseline value for the respected group will be assigned. If complete questionnaires or objective measures are missing a non-responder imputation will be used, including baseline data carried forward. Sensitivity analyses will be performed to study whether those who drop out differ from those who complete the required program.
An analysis of covariates (ANCOVA) will be used to analyse mean changes in continuous variables, and logistic regression for categorical variables. The model will include the respective dependent variable, in addition to fixed effects of group allocation, baseline value, age, gender and height.
The results will be expressed as a difference between the group means and 95% confidence intervals with associated p-values. The main analyses will be conducted by a statistician not involved in the testing and blinded to group allocation. All data analysis will be performed according to a pre-established statistical analysis plan and interpreted according to a consensus document signed by all authors. All analyses will be performed using Statistical Package for Social Sciences (SPSS) (version 25, IBM, New York, USA).
Interim analyses
Drop-out rates will be assessed in interim analyses to determine potential need for adjustment in sample-size in line with the power calculations.
Ethical considerations
Although participants may experience increased symptoms in the short-term, it is not anticipated that participation will cause any serious adverse events or harms. A recent feasibility study (27) has confirmed that the intervention BI-VR and VR-CBT is feasible and safe for persons with persistent dizziness. If participants experience harm from the treatment delivered within the study, this will be registered, and the person will be directed for further assessment and follow-up care in accordance with the provisions that are customary within the national, public health care system. The study will follow the criteria and principles of the Declaration of Helsinki. It has been approved by the Regional Committee for Medical and Health Research Ethics (2014-00921) and is registered at www.clinicaltrials.gov (NCT02655575)