Treating prolonged grief disorder with prolonged grief-specific cognitive behavioral therapy: study protocol for a randomized controlled trial

BACKGROUND: Prolonged grief disorder (PGD) has emerged as a well-defined and relatively common mental disorder that will be included in the upcoming revision of the International Classification of Diseases. Recent trials with grief-specific, mostly cognitive behavioral interventions for patients with a clinically relevant diagnosis of PGD showed large effect sizes. However, a small trial suggested that non-specific behavioral activation might suffice to improve PGD. So, more evidence for the relative efficacy of grief-specific treatments is needed, as is more research on the predictors of treatment success. The purpose of the proposed trial is to evaluate a newly developed and successfully pilot-tested, prolonged grief-specific, integrative cognitive behavioral therapy (PG-CBT) compared to an active yet unspecific treatment, present-centered therapy (PCT). METHODS: In a multicenter, randomized controlled trial with 204 adults with a primary diagnosis of PGD, PG-CBT is compared to PCT, assuming the superiority of PG-CBT. Both treatments consist of 20 to 24 individual sessions, with an overall treatment length of about 6 months. The primary outcome, grief symptom severity, is assessed by blinded interviewers 12 months after randomization. Secondary outcomes are grief symptom severity at post treatment, in addition to self-reported overall mental health symptoms, depressive and somatoform symptoms at post treatment and 12 months post randomization. Possible moderators and mediators of treatment success are also explored. DISCUSSION: The trial is designed to avoid bias as much as possible (stratified randomization performed independently, blinded outcome assessment, intention-to-treat-analysis, balanced treatment dose, continuous supervision, control for allegiance effects) thereby enhancing internal validity. At the same time, some aspects of the trial will ensure clinical relevance (recruiting at outpatient clinics that are part of routine health care and keeping exclusion criteria to a minimum). Since the trial is powered adequately for the primary outcome, all secondary analyses including moderator analyses are exploratory by nature. The results will extend the knowledge on efficacious treatment of PGD and its predictors. TRIAL REGISTRATION: German Clinical Trials Register, ID: DRKS00012317. Registered on 6 September 2017. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13063-018-2618-3) contains supplementary material, which is available to authorized users.