EMDR as an innovative strategy in the treatment of OCD

A widely accepted first-line treatment for obsessive-compulsive disorder (OCD)
is exposure and response prevention (ERP). However, approximately half of the
patients do not respond optimally to this treatment, and about 25% of OCD
patients refuse the treatment or drop-out prematurely. Hence, the development
of innovative strategies for OCD is of paramount importance. Recent studies
suggest that overall treatment resistance is likely associated with the
intrusive images (e.g., causing illness and death) that 90% of the OCD patients
experience. Eye Movement Desensitization and Reprocessing (EMDR) has
established efficacy in reducing the impact of traumatic images in various
disorders.

The aim is to critically evaluate the additive effect of EMDR to ERP on
treatment acceptability, drop-out, and outcome; a) does EMDR lead to a decrease
in OCD related memory representations (or in other words; does it lead to a
decrease in the amount of obsessions)? ;b) are patients more inclined to be
subjected to ERP after EMDR and less inclined to drop-out then before they
received EMDR? and c) does the combinated use of EMDR and ERP to an additional
observable effect by reducing drop-out and a higher decrease in OCD symptoms?

An experimental multiple baseline case series design is used (Kazdin, 2011),
consisting of 4 phases, i.e., baseline, exploration, treatment, and
return-to-baseline phase. Different baseline lengths are determined before the
start of the study (i.c., 3, 4, 5, 6, and 7 weeks). After inclusion each
patient is allocated a) alternately to one of both therapists, and hereafter b)
randomly to one out of 5 baseline lengths (2 patients for each baseline length,
baseline lengths equally divided between both therapists). Since the Altrecht
Academic Anxiety Centre is a highly specialised treatment centre, to which only
severe and chronic patients are referred, it is expected that complaints
(YBOCS) at baseline will be stable. At the end of the baseline phase the
patient is asked to rate the two VASs on willingness to engage in ERP, and
inclination to drop out of ERP. After the baseline phase, the exploration phase
(4 weeks) starts. During this phase no active interventions are used, thus
serving as an additional control phase. This is followed by the active
treatment phase, starting with 6 sessions EMDR. At the end of the last EMDR
session the patient is asked again to rate both VASs on ERP. Hereafter 15
sessions ERP are conducted (or more if needed). After treatment there is a
*return-to-baseline* phase of 6 weeks, in which the patient receives no
treatment.

Although RCTs are generally considered the *golden standard* for testing
therapy effectiveness, there are limitations with respect to feasibility,
costs, and external validity (e.g., Hawkins et al., 2007). Therefore, as a
first step often an open trial is used in order to explore the effect of an
intervention. However, this design offers no solid base for conclusions. A
powerful alternative is a multiple baseline case series design (Onghena, 2005).
Advantages are that a) patients serve as their own controls, and b) variation
in baseline lengths offers the possibility to differentiate between time
effects and experimental effects of the treatment. By adding an exploration
phase, it is also possible to control for the effect of attention, and the
power of the design is increased (see Arntz, Sofi, & van Breukelen, 2013).
Moreover, multiple baseline case series fit in with daily practice more closely
than RCTs, and offer the opportunity to continue treatment (i.c., ERP) until
adequate reduction of complaints is reached (Kazdin, 2011). There is also an
ethical advantage, whilst in comparison to RCTs, less patients have to be
included.
Multiple baseline case series are less suited to directly compare the effect of
two different treatments; for that purpose between-subjects designs are needed.
However, it is explicitly not the aim of our study to determine the relative
effect of EMDR and ERP. Our goal is to examine the additive effect of EMDR;
hence a carry-over effect of EMDR on ERP is expected. Moreover, it was decided
not to use a cross-over design (alternating order of EMDR and ERP), since it is
expected that EMDR especially has a favourable additive effect when preceding
ERP (by more willingness to engage in ERP, and less inclination to drop-out).
Finally, if the expected effects are not found, this provides a strong argument
that EMDR has no benefits in OCD. However, when the expected effects do appear,
EMDR is considered a promising treatment component in this specific patient
group, making a formal RCT a logical further step.

6 x weekly session of Eye Movement Desensitization and Reprocessing (EMDR)
15 x weekly session of Exposure & Responspreventie (ERP)


ERP is the standard intervention; next to this patients receive 2 sessions
idiosyncratic case-conceptualisation (45 minutes each) in which targets are
selected for EMDR and the treatment rationale is explained, followed by 6
sessions (90 mintues each active EMDR treatment.

There are no risks involved by participation in this study.

Most secondary outcome measures are part of a standard measurement procedure at
the Altrecht Academic Anxiety Centre, i.e., part of *Routine Outcome
Monitoring* (ROM). Whether a patient is enrolled in the present study or not,
all patients have to complete ROM measurements during their treatment. The
burden for patients who will participate in the present study is:

a) - at two times (before and at the end of EMDR treatment) they have to
endorse two Visual Analogue Scales (placing a cross on a line) concerning their
inclination to drop out during ERP, and their willingness to fully engage in
ERP (2 min per time);
- each week they have to endorse the YBOCS, a short questionnaire into the
severity of OCD symptoms (5 min per week). During the baseline and
return-to-baseline phases the YBOCS is send to the patient, so he/she can
endorse the questionnaire at home; during the exploration and active treatment
phase, the patient endorses the questionnaire at location (AAA), just before a
treatment appointment.

b) 2 sessions idiosyncratic case-conceptualisation (selection of targets to be
processed with EMDR) and explanation of the rational of EDMR treatment (2x45
minutes)

b) 6 sessions (6x90 minutes) active EMDR treatment.