Group Intervention for Interpersonal Skills

Change in interpersonal functioning, measured with the IIP-32 from baseline (Time 1) to week 14 (Time 2), represents the primary outcome measure. The IIP-32 is a self-assessment questionnaire for interpersonal problems, i.e., difficulties in interacting with other individuals, based on Horowitz's Circumplex Model. It consists of 32 items that are answered on a 5-point scale (0= not at all, 4 = very much). For evaluation, a mean score is calculated across all items, with a higher score indicating a higher severity of interpersonal problems.

The IIP-32 is a self-assessment questionnaire for interpersonal problems, i.e., difficulties in interacting with other individuals, based on Horowitz's Circumplex Model. It consists of 32 items that are answered on a 5-point scale (0= not at all, 4 = very much). For evaluation, a mean score is calculated across all items, with a higher score indicating a higher severity of interpersonal problems.

As key secondary endpoint, observer-rated changes in interpersonal functioning from Time 1 (week 1) to Time 2 (week 14) will be investigated with the IMI-R. The IMI-R will be conducted by blinded study raters. The IMI-R uses 64 items (8 items for each Kiesler Circle position) to capture covert reactions that a patient evokes in a blinded-rater. Through this assessment, it is possible to create an individual Kiesler Circle profile for each patient. The assessment of each behavior is conducted on a 4-point scale (1 = strongly disagree; 4 = strongly agree), so that higher values mean a higher expression of the Kiesler Circle position.

The HAMD is a semi-structured interview, which measures the severity of depressive symptoms experienced in the last week. Blinded study raters will assess the severity of symptoms for each of the 24 items using a scale ranging from 0-2, 0-3, or 0-4. The total score ranges from 0-75, with higher scores indicating a higher severity of depression.

The BDI-V is a self-report questionnaire designed to assess the severity of depressive symptoms. Patients rate the severity of 20 depression symptoms on a 6-point scale (0 = never, 5 = almost always). The total score ranges from 0 to 100, with higher scores indicating a higher severity of depression.

The HAM-A is a clinician-rating to assess the severity of anxiety symptoms experienced in the last week. Blinded raters will assess the severity of symptoms for each of 14 items using a 5-point scale ranging from 0 to 4. The total score ranges from 0 to 56, with higher scores indicating a higher severity of anxiety.

The ACA is a self-report questionnaire of which we assess two subdomains in our study: the Body Sensations Questionnaire (BSQ) and the Agoraphobic Cognitions Questionnaire (ACQ). The BSQ asks about anxiety regarding 17 physical symptoms and the ACQ about 14 catastrophizing thoughts that can occur during anxiety. Answers are given on a 5-point scale, with higher scores indicating higher levels of anxiety (1 = not anxious/never, 5 = extremely anxious/always). A mean value is calculated for each of the two subdomains.

The SEDI is a short form of the Multidimensional Emotional Disorder Inventory (MEDI; Rosellini & Brown, 2019), which represents a dimensional approach to classify emotional disorders. The SEDI is a self-report questionnaire comprising 15 items that are answered on a 4-point scale (1 = completely untrue or slightly true, 4 = completely true). A mean value is calculated over all items, with higher values indicating a higher level of emotional disorder traits.

The PHQ-9 is part of the Patient Health Questionnaire and measures depressive symptoms using 9 items. The rating scale is 4-point (0 = never, 3 = almost daily) and a total score ranging from 0-24 is calculated.

The PHQ-15 is part of the Patient Health Questionnaire and measures the 15 most common somatic symptoms of outpatients. The rating scale is 3-point (0 = not affected, 2 = severely affected) and a total score ranging from 0-30 is calculated.

The GAD-7 was integrated into the patient health questionnaire in 2006 as a validated scale for measuring generalized anxiety disorder using 7 items. The rating scale is 4-point (0 = never, 3 = almost daily) and a total score ranging from 0-21 is calculated.

The WHOQoL-BREF is a self-report measure and assesses the subjective quality of life across physical, psychological, social, and environmental domains using 26 items. These domains are rated by patients on a 5-point scale and a mean score for each domain is calculated by multiplying the mean value of all items of the respective domain by four. The possible values for all domain scores therefore range from 4-20.

The PID5BF+M is a self-report questionnaire designed to assess maladaptive personality traits in alignment with the DSM-5 and ICD-11. The questionnaire comprises 36 items, which are answered on a 4-point scale (0 = completely untrue, 3 = completely true) and captures six personality trait domains (negative affectivity, detachment, antagonism/dissociality, disinhibition, anankastia, and psychoticism). A mean value is calculated for each domain, with higher scores indicating higher expression of that personality domain.

The LPFS-BF is a self-report questionnaire designed to assess personality functioning in alignment with the DSM-5 and ICD-11. The questionnaire comprises 12 items, which are answered on a 4-point scale (1 = completely untrue, 4 = completely true) and captures two personality functioning domains (self and interpersonal pathology). A mean value is calculated for each domain, with higher scores indicating higher expression of that personality functioning domain.

The Interpersonal Needs Questionnaire (INQ) measures interpersonal needs using two subscales: thwarted belongingness and perceived burdensomeness. The questionnaire consists of 15 items, that are answered on a 7-point scale (1 = completely untrue, 7 = completely true). After reversing the polarity of 6 items, a mean value is calculated for each of the two subscales, with higher scores indicating higher levels of thwarted belongingness and perceived burdensomeness.

Childhood maltreatment is assessed as a main moderator at baseline. The CTQ is a self-report assessment designed to measure experiences of childhood trauma and abuse on five subscales (emotional abuse, physical abuse, sexual abuse, emotional neglect and physical neglect). Patients rate the frequency of 34 of these experiences on a 5-point scale (1= not at all, 5 = very often), and each subscale score has a range from 5 to 25 points. Higher scores indicate a higher severity in childhood trauma.

Patients answer short questionnaires four times a day, which appear on their smartphone at random times (Electronical Momentary Assessment, EMA). The number of social contacts, the quality of social contacts (interpersonal complementarity), interaction partner, affect and anxiety are assessed.

The INEP is a self-report assessment of negative changes caused by psychotherapy in the areas of intrapersonal change, relationships, friendships, family, malpractice, and stigmatization. The INEP contains 21 items, which responses are partly formulated in a 7-point bipolar format (-3 = negative change is completely true, 0 = unchanged, 3 = positive change is completely true), and partly formulated in a 4-point unipolar format (0 = completely untrue; 3 = completely true). In addition, patients' attributions regarding the cause of negative effects is assessed. For the evaluation, only negative effects directly attributed to the psychotherapeutic treatment are considered.

The NUGE assesses adverse experiences with group psychotherapy and side effects of the group setting by differentiating between group-related and therapist-related stress, stress from co-patients and personal overload. The NUGE comprises 24 items and responses are given on a 5-point scale (1 = strongly disagree, 5 = strongly agree), with higher scores indicating higher distress. The NUGE will be completed after each KCT group session by patients randomly assigned to the intervention group.