The (Cost-)Effectiveness of Generalist Versus Specialist Treatment for Severe Personality Disorders'

Level of Personality Functioning Scale - Brief Form 2.0 (LPFS-BF 2.0)

The LPFS-BF 2.0 is a self-report questionnaire consisting of 12 items (Weekers et al., 2018). Each item reflects a basic underlying impairment related to the 12 features of personality functioning according to Criterium A of the AMPD such as identity, self-direction, intimacy and relational functioning. The LPFS-BF 2.0 offers a severity index for personality pathology making it suitable for measuring treatment effects. Each item is scored on a scale from 1 (=very false or often false) to 4 (=very true or often true). Therefore, participants achieve a total score between 12 and 48 representing the severity of impairment in personality functioning. Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

Semi-structured Interview for Personality Functioning (STiP-5.1)

The STiP-5.1 is a semi-structured clinical interview that provides a multi-item assessment of the severity of personality impairments according to the Level of Personal Functioning Scale (LPFS) of the AMPD included in Section III of DSM-5 (APA, 2013). The interviewer should rate the severity of each facet on a scale ranging between 'little to no impairment' (0) to 'extreme impairment' (4). It takes 45 minutes on average to administer the interview. A total score between 0 and 48 is given to indicate the participants global level of personality functioning . We administer the STiP-5.1 at 3 distinct time points. At the start and end of treatment and after 1 year follow up. All interviews are done by blinded research assistants, and the scores are directly logged in Castor. Interviews will be done either face to face or via video call.

Severity Indices of Personality Problems - Short Form (SIPP-SF)

The SIPP-SF is a dimensional self-report questionnaire measuring the severity of personality pathology by assessing the core components of adaptive personality functioning. The SIPP-SF is designed in line with the concept of personality disorders as defined in the AMPD. Participants rate the 60 items on a 4-point scale ranging from fully disagree (1) to fully agree (4). Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

Brief Symptom Inventory (BSI)

The BSI is a self-report questionnaire investigating symptom severity, consisting of 53 items which can be answered using a scale ranging from 1 (not at all) to 5 (extremely). The total score represents the number of symptoms that participants experienced during the past week. A global severity index and sub scores on all 9 domains are calculated by summing the values on all items and dividing by the number of items/domains. Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

Columbia Suicide Severity Rating Scale Screen Version (C-SSRS)

Suicidality is assessed using the C-SSRS. This self-report questionnaire covers 6 items and has been recommended by ICHOM as a standard outcome measurement in personality disorder research, due to its adequate psychometric properties (Prevolnik Rupel et al., 2021). The 6 items are answered with either 'yes' or 'no'. The total number of positive answers indicates suicide risk. Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

SCID-5-PQ

The SCID-5-PQ (First et al., 2016) is a self-report measure assessing different criteria for DSM-5 personality disorders according to Section II. Participants are presented with 106 items describing whom they are as a person providing them with a dichotomous 'yes' or 'no' answer scheme. Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

The Childhood Trauma Questionnaire - Short Form (CTQ-SF)

The CTQ-SF employs 25 items to assess childhood trauma and distinguish between emotional neglect, physical neglect, emotional abuse, physical abuse and sexual abuse (Bernstein et al., 2003). All statements start with "When I was growing up..." and are answered on a 5-point scale ranging from 1 (never true) to 5 (very often true). Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

PTSD Checklist for DSM-5 (PCL-5)

The PCL-5 aims to screen for post-traumatic stress disorder using 20 items that correspond to the DSM-5 criteria (Blevins et al., 2015). Likewise, the four subscales correspond to the DSM-5's clusters B through E for PTSD. The 20 items are answered on a 4-point scale ranging from 0 (not at all) to 4 (extremely) resulting in scores ranging between 0 and 80. Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

Autism Spectrum Quotient

The 5-item version of the Autism Spectrum Quotient (AQ-5) is a very brief screener, which has been derived from the AQ-10. The AQ-5 measures social communication deficits, corresponding to Criterion A of the ASD-diagnosis. The scale has acceptable internal consistency and convergent validity. Items are rated on a 4 point scale ranging from 'definitely disagree' to 'definitely agree'. Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.

the subscale Motivation to Engage of the Treatment Motivation Scales for forensic outpatient treatment (TMS-F)

Patient commitment to treatment is measured with a selection of items from the subscale Motivation to Engage of the TMS-F. The four items can be rated on a 7-point Likert scale . Data collection is done digitally via Castor or with pen and paper, based on participants preference. Pen and paper results are copied into Castor by hand by research assistants. Raw data is digitalized and stored on a local drive.