A Feasibility Study of Internet Delivered Prolonged Exposure

Number of imaginal exposures made by the participant during the treatment

Number of in vivo exposures made by the participant during the treatment period

The proportion of participants that conducts the weekly measures and further assessment points

The proportion of participants that go through the entire treatment period

Treatment acceptability

Treatment acceptability

Qualitative interviews

The CSQ-8 yields a single score measuring a single dimension of overall satisfaction. An "overall score" is calculated by summing the score on each of the eight scale item. Scores range from 8 to 32, with higher values indicating higher satisfaction.

The CAPS-5 is structured interview that assesses the Diagnostic and Statistical Manual of Mental Disorders version 5 (DSM-5) criteria for PTSD (Weathers et al., 2013). Each item is rated on a severity scale ranging from 0 (Absent) to 4 (Extreme/incapacitating) and combines information about frequency and intensity for each of the 20 symptoms. Total Score (Range 0-80 with higher scores representing more PTSD symptoms.

The PCL-5 is a 20-item self-report measure based upon the Diagnostic and Statistical Manual (DSM-5) criteria for PTSD. Total Score (Range 0-80 with higher scores representing more PTSD symptoms.

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.