The proportion of completed group-sessions

The ITQ includes six items measuring each PTSD symptom cluster and these items measure how bothersome each symptom has been in the past month. The ITQ also includes six items measuring each 'Disturbance in Self-Organization' (DSO) symptom in complex PTSD. These items measure how a respondent typically feels, thinks about oneself, and relates to others. The PTSD and DSO symptoms are accompanied by three items measuring associated functional impairments in the domains of social, occupation, and other important areas of life. All items are answered on a 5-point Likert scale ranging from 0 (Not at all) to 4 (Extremely). Thus, PTSD and DSO symptom scores range from 0 to 24 and CPTSD symptom scores range from 0 to 48. Higher scores represents more PTSD and complex PTSD symptoms.

The PHQ-9 is a widely used and well-validated instrument for measuring the severity of depressive symptoms. Scores are calculated based on how frequently a person experiences 9 symptoms of depression ranging from "not at all" response is scored as 0; "several days" response is 1; "more than half the days" response is 2; and "nearly every day" response is 3. Higher scores represents more depressive symptoms.

Change in overall health from baseline to post treatment and follow up . EQ-5D is a standardized self-report measure of overall health status measured in terms of five dimensions; mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Mobility dimension asks about the person's walking ability. Self-care dimension asks about the ability to wash or dress by oneself, and usual activities dimension measures performance in "work, study, housework, family or leisure activities". In pain/discomfort dimension, it asks how much pain or discomfort they have, and in anxiety/depression dimension, it asks how anxious or depressed they are. The respondents self-rate their level of severity for each dimension using a three-level scale: 1 having no problems, 2 having some problems and 3 having extreme problems. A higher score indicate worse severity.

Change in tendency to engage in excessive and uncontrollable worry from baseline to post-treatment and follow-up.

The Penn State Worry Questionnaire (PSWQ) is a standardized self-report measure assessing the general tendency to experience persistent, excessive, and uncontrollable worry. It measures the extent to which worry is perceived as pervasive, distressing, and difficult to control across situations. The scale consists of 16 items rated on a 5-point Likert scale ranging from 1 ("not at all typical of me") to 5 ("very typical of me"). Items reflect frequency, intensity, and uncontrollability of worry. Higher scores indicate a greater tendency toward pathological worry.

Change in The Generalized Anxiety Disorder scale (GAD-7), a standardized self-report measure of general anxiety symptoms. It consists of 7 items assessing the frequency of core anxiety symptoms such as excessive worry, tension, restlessness, irritability, and difficulties relaxing or concentrating. Respondents rate how often they have been bothered by each symptom over the past two weeks on a 4-point scale ranging from 0 ("not at all") to 3 ("nearly every day"). Total scores range from 0 to 21, with higher scores indicating more severe anxiety.

Self-rated questionnaire on negative effects. It contains 20 items that are scored on a five point Likert-scale (0-4) and differentiates between negative effects that are attributed to treatment and those possibly caused by other circumstances. The total score of the NEQ ranges from 0 to 80 points, a higher score reflects more negative effects.