Emetophobia Clinical Trial
Official title:
Time Intensive Cognitive Behavioural Therapy for a Specific Phobia of Vomiting Using a Single Case Experimental Design
The aims of this project are to determine the effectiveness of a time intensive form of Cognitive Behavioural Therapy (CBT) for Specific Phobia of Vomiting (SPOV). Current research shows that this brief format can be effective in other specific phobias e.g. insects and animals. However, to date limited research has been conducted on the effectiveness of time intensive forms of CBT for SPOV. A single case experimental design will be used to analyse specific and idiosyncratic outcome measures in 6-8 cases of SPOV, referred to the Centre for Anxiety Disorders and Trauma (CADAT) for treatment. Specifically, the project will explore the effectiveness of CBT delivered in a time-intensive format and imagery rescripting elements of the treatment. This initial study will provide important information about which elements of CBT are most effective at reducing targeted symptoms and whether symptom reduction can be achieved in a shorter number of sessions. It represents a crucial step before this format of CBT can be more rigorously evaluated and compared to other treatment approaches by Randomised Controlled Trial.
Design A single case experimental design (ABACADA) will be used. A, B, C etc represents
points of intervention and clinical contact with participants when standardised outcome
measures will be administered by the treating clinician at each session. Phases A1, A2, A3
represent time between contact during which participants will undertake daily monitoring of
idiosyncratic symptoms on Visual Analogue Scales (VAS) e.g. degree of avoidance, degree of
worry, degree of nausea etc, so change between phases across time can be measured.
Participants will be randomly allocated to differing lengths of baseline phase (initial
clinical assessment to first clinical session) with 4 potential arms (7, 10, 14, or 17 days).
The first three clinical sessions (formulation, imagery rescripting and planning of intensive
days) will take place weekly and last up to 1.5 hours. The two intensive days will last up to
4 hours each and take place shortly after the planning session and within a few days of each
other. Three additional follow up sessions will be offered within 10 days of the intensive
days (2 within one week, and the final session one week after). Follow up data will be
collected by phone or post 3, 6 and 12 months post intervention.
Participants Participants will be recruited from consecutive referrals to CADAT for treatment
of SPOV. Clients will have a diagnosis of SPOV as defined by the Diagnostic and Statistical
Manual of Mental Disorders (DSM-V) as their main presenting problem. They will be drawn from
the CADAT waiting list, and if necessary from Improving Access to Psychological Therapy
(IAPT) services at Southwark, Lambeth and Lewisham. These cases will be picked up by and
treated at CADAT by qualified clinicians.
Participants are expected to be involved in the study for up to 8 weeks for the treatment
phase, and 12 months for follow up data to be collected.
Recruitment Consultant Psychiatrist for the team at the Centre for Anxiety Disorders and
Trauma will identify potential participants from the waiting list at CADAT who meet the
inclusion criteria to take part in the study. Potential participants will then be asked if
they would like to participate at the initial clinical assessment. They will be provided with
an information sheet and the opportunity to ask questions before making a decision and giving
informed consent.
Sample size It is estimated that 6-8 cases will be sufficient for a single case experimental
design to demonstrate proof of concept. This is based on previous studies using a similar
design.
Procedure Patients identified from the CADAT waiting list and who meet the study criteria
will be asked at assessment if they would like to participate in the study. Those who are
interested in taking part will be given an information sheet, and the opportunity to ask
questions before making a decision on their participation. They will then be asked to provide
informed written consent by signing a consent form before continuing with the study
procedure. Clinicians will remind all participants of their right to withdraw from the study
at any time, which will not affect their care or right to treatment as usual. Participants
will then receive the time intensive form of CBT for their SPOV.
To ensure therapist adherence to the time intensive format of the treatment, a separate
treatment protocol has been provided as part of Standard Operating Procedures. This protocol
is as follows:
- Assessment and signing of consent form
- Session 1: Re-baseline & Formulation (including a conversation about early memory of
vomiting)
- Session 2: Imagery Rescripting of early memory of vomiting
- Session 3: Planning for Intensive Days
- Intensive Day 1
- Intensive Day 2
- 3 short clinical follow up sessions
Standardised outcome measures will be collected at baseline, intervention and follow up
phases. Participants will also be asked to collect daily idiosyncratic measures in between
the intervention phases. Participants will be randomly allocated to differing lengths of
baseline to the time of the intervention with 4 potential arms (7 days, 10 days 14 days or 17
days). This will be done using a simple spreadsheet by a Research Assistant at CADAT. The
baseline discussion around the memory of vomiting, imagery re-scripting and treatment
planning will consist of 1-1.5 hour sessions. Time intensive treatment will consist of two
sessions over 2 days (4 hours each). Three additional follow up sessions will be
administered, 2 within 1 week of the intensive days and a third 1 week after the second
follow up session. The same standardised outcome measures will be collected at 3, 6 and 12
months by phone or post.
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