Group Schema Therapy for Cluster-C Personality Disorders: a pilot study.

The main outcome variable is change in severity of manifestations of the primary PD. The severity of PD manifestations will be assessed with the AVPDSI (for Avoidant PD), the DEPDSI (for Dependent PD), and the OCPDSI (for Obsessive Compulsive PD): structured interviews for assessing the frequency of various manifestations of DSM5 defined Avoidant, Dependent and Obsessive- Compulsive PD criteria during the last 3 months (Baljé et al., 2016; Arntz et al., 2017; Verheul et al, 2017).

1. PD-related beliefs will be assessed with the PDBQ-69 (Arntz et al., 2004), of which the beliefs
specific for Avoidant, Dependent, and Obsessive-Compulsive PD will be taken.

2. Self-esteem will be assessed with the 10-item version of Rosenberg’s Self-Esteem Scale (RSES;
Rosenberg, 1965; Franck et al., 2008).

3. Self-Ideal Discrepancy will be assessed by calculating the difference between the Self and Goal
scales of the Miskimins Self-Goal-Other Discrepancy Scale (MSGO; Miskimins et al., 1971).

4. General, social and societal functioning will be assessed with the WHODAS, taken by the research
assistant (Üstün, 2010).

5. Happiness will be assessed with the 1-item happiness question validated in more than 30 countries
(Veenhoven, 2011).

6. Quality of Life will be assessed with the EuroQol EQ-5D-5L (Herdman et al., 2011; Rabin & Charro,
2001).

7. Schema Modes will be assessed with the Schema Mode Inventory-2 (SMI-2; Bamelis et al., 2011),
which assesses the frequency of Schema Mode activation for the modes relevant for the pertinent
PDs.

8. Early Maladaptive Schemas will be assessed with the YSQ-Revised, a shortened version of the
YSQ (YSQ-R; Rijkeboer, 2013).

9. General psychopathological symptoms as an index of severity of syndromal disorders will be assessed with the Brief Symptom Inventory (BSI; Derogatis & Melisaratos, 1983).

10. Medication and mental health care use will be monitored at each assessment.