Preference Effects in the Treatment of Panic Disorder

Abstract: Patient preferences have drawn considerable attention as a potential moderator of treatment outcome. The Doubly Randomised Controlled Preference Trial (DRCPT) in which patients are randomised to a choice between two or more treatments or random assignment to one of these same treatments is considered one of the most rigorous tests of the effects of patient preferences on outcomes. To date, there have been no DRCPTs involving the choice between two psychological treatments for any psychiatric disorder. A DRCPT was conducted in which 221 adults with a primary diagnosis of Panic Disorder with or without Agoraphobia (PD/A) were randomly allocated to choose between Panic Control Treatment (PCT) and Panic Focused Psychodynamic Psychotherapy (PFPP), or to random assignment to these two treatments. The primary outcome measures were the Panic Disorder Severity Scale (PDSS), work status and sick leave assessed at post-treatment, 6-, 12-, and 24-month follow-ups. A range of secondary outcomes were assessed at these same intervals. The DRCPT, titled Project POSE (Psychotherapy Outcome and Self-selection Effects), was carried out in the southern part of Sweden between 2010 and 2019. Project POSE, from which this program of PhD research is drawn, had two primary aims: 1) to assess the effects of patient treatment preferences on the primary and secondary outcomes at post-treatment and follow up; and 2) to compare outcomes for PCT and PFPP on the primary and secondary outcomes at post-treatment and follow-up. The primary aims of this PhD were: 1) to assess the effects of patient choice of treatments on the primary outcomes at post-treatment and follow-up; and 2) via qualitative and quantitative methods to better understand why participants randomised to the choice condition chose either PFPP or PCT; and 3) to evaluate the validity of the Swedish version of the PDSS, which served as the primary (interview version) and secondary (patient-report version) measures of PD/A severity in the trial. Study I identified an important gap in the literature with respect to a need for studies that could experimentally test the role of patient treatment preferences on outcomes in psychotherapy. Study II established that that the Swedish translations of the PDSS and PDSS-SR possessed high levels of internal consistency and concurrent validity, as well as a factor structure similar to the English-language original, suggesting they were valid for use as a primary/secondary measures in the DRCPT. Study III found that when offered a choice between PCT and PFPP, the resulting choice was primarily a function of the individual’s beliefs about the chosen therapy, its potential for success, and their own learning style. Contrary to expectation, Study IV found no differences for the primary and secondary outcomes at post-treatment or long-term follow-up for patients randomised to the treatment choice and random allocation to treatment conditions. However, a disordinal interaction, albeit non-significant, on the PDSS, suggested that the effect of treatment preferences on outcomes for PD/A may have been moderated by treatment type (PCT or PFPP).