Role of Online Discussion Forums in Unguided Internet-Delivered Cognitive Behavioural Therapy for Canadian Public Safety Personnel: A Randomized Trial

Change in Depression

时间窗: Baseline, 8 weeks, 20 weeks

Patient Health Questionnaire-9. The Patient Health Questionnaire-9 (PHQ-9) is a commonly used measure of depression that includes an item to measure suicidality (Kroenke et al., 2001). It has demonstrated excellent psychometric properties in many studies (e.g., Cameron et al., 2008; Kroenke et al., 2001, 2010). Its nine items are rated on a four-point Likert scale from 0 (not at all) to 3 (nearly every day) for a total score ranging from 0 to 27. Traditionally, a score of 10 or greater has been considered indicative of a likely diagnosis of major depressive disorder on the PHQ-9 (Manea et al., 2012). A change in score of six points has been identified as a reliable change index (National Collaborating Centre for Mental Health, 2019).

Change in Anxiety

时间窗: Baseline, 8 weeks, 20 weeks

Generalized Anxiety Disorder-7. The Generalized Anxiety Disorder-7 (GAD-7) is a seven-item measure of generalized anxiety symptoms. Like the PHQ-9, its items are rated on a four-point Likert scale from 0 (not at all) to 3 (nearly every day). Possible total scores range from 0 to 21. Research shows that the GAD-7 has strong psychometric properties, and a score of 10 or greater can be used to indicate a likely diagnosis of generalized anxiety disorder (Kroenke et al., 2010; Spitzer et al., 2006). Following the precedent of other ICBT researchers, a change in score of five points or more will be considered clinically significant (Titov et al., 2017).

Change in Posttraumatic Stress

时间窗: Baseline, 8 weeks, 20 weeks

PTSD Checklist for DSM-5. The PTSD Checklist for DSM-5 (PCL-5) is a common measure of PTSD that was updated following the release of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; (American Psychiatric Association, 2013; Blevins et al., 2015; Weathers et al., 2013). It includes 20 items that are rated on a five-point Likert scale from 0 (not at all) to 4 (extremely), for a total score between 0 and 80. Several research groups have suggested that a score of 33 or greater indicates a likely diagnosis of PTSD (Bovin et al., 2016; Wortmann et al., 2016). A change in score of 10 points or more is considered a reliable change on the PCL-5 (Byllesby et al., 2019). At baseline (but not at later timepoints), the investigators will administer a version of the PCL-5 that includes five additional questions about the nature of the potentially psychologically traumatic event that a respondent experienced (Weathers et al., 2013).