Individual Psychotherapy for Cluster C Personality Disorders: A pragmatic RCT comparing time limited Psychodynamic, Affect Phobia and Schema Therapy

Cluster C personality disorders (PDs) are highly prevalent in clinical practice
and are related to unfavorable outcome and chronicity of all common mental
health disorders (e.g. depression and anxiety disorders). Although several
forms of individual psychotherapy are commonly offered in clinical practice for
this population, due to scarcity of well-designed studies evidence for
differential efficacy, setting and format is lacking. Also, very little is
known on working mechanisms of these psychotherapies. Finding evidence on the
differential (cost)effectiveness for this group of patients and the working
mechanisms of change is important to improve the quality of care for this
vulnerable group of patients.

In this study we will compare the differential (cost)- effectiveness of three
individual psychotherapies: short-term psychodynamic supportive psychotherapy
(SPSP), affect phobia therapy (APT) and schema therapy (ST). Although these
psychotherapies are commonly used in clinical practice, evidence for the
cluster C PDs is restricted to one RCT for ST (Bamelis et al., 2014) and one
for APT (Svartberg et al., 2004). Next we will investigate predictive factors,
non-specific and therapy specific mediators.

A mono-center randomized clinical trial with three parallel groups 1) SPSP 2)
APT 3) ST. Randomization on patient level will be pre-stratified according to
type of personality disorders.

SPSP, APT and ST (50 sessions per condition) are offered twice a week in
sessions of 50 minutes for the first four to five months. After that, session
frequency decreases to once a week. All conditions have a maximum duration of
one year.

Patients will be invited to a clinical interview prior to start of treatment,
12 and 24 months after start of treatment. Other measurements can be done
either online or on paper-and-pencil. Although the burden includes a
time-investment of the patient (by filling in questionnaires), no risks are
associated with participation in the study. Participators in all conditions
will receive specialized treatment for personality disorders, their treatment
and measurements will be well monitored and checked on adherence and additional
treatment is provided if necessary.