Do beliefs about treatment credibility and expectancy influence the outcomes of cognitive behavioral therapy for insomnia among cancer survivors

Objectives: Cognitive Behavioral Therapy for Insomnia (CBT-I) effectively improves insomnia and perceived cognitive impairment (PCI) in cancer survivors. This prespecified secondary analysis assessed how credibility and expectancy beliefs influence insomnia and PCI outcomes, and explored what factors were associated with higher beliefs about credibility and expectancy. Methods: As part of a randomized waitlist-controlled trial, cancer survivors (N = 132) who met the DSM-5 criteria for insomnia disorder and reported PCI received 7 weekly virtual CBT-I sessions. Credibility and expectancy beliefs were assessed separately for insomnia and PCI using the Credibility Expectancy Questionnaire. We also examined whether credibility and expectancy moderated change in symptoms of insomnia and PCI, controlling for age. Factors associated with greater credibility and expectancy beliefs were evaluated using linear regression and qualitative interviews were used to explore patient perceptions. Results: Only younger age was associated with higher pre-treatment expectations for insomnia and PCI outcomes (p = 0.009; p = 0.008). Beliefs about credibility or expectancy did not moderate change in symptoms of insomnia (p = 0.972; p = 0.502) or PCI (p = .143; p = 0.283). Qualitative results suggest that skepticism and doubt, one’s understanding of sleep, and optimism and open-mindedness influence expectation of outcome and perceptions of treatment credibility. Conclusion/Implications: CBT-I has robust efficacy regardless of pre-existing beliefs and expectations. While these factors may play a role in the decision to pursue CBT-I, our results suggest that clients are likely to experience benefits if they sufficiently engage in the therapy. Treatment outcomes may be enhanced by: 1) providing psychoeducation about sleep; 2) setting appropriate pre-treatment beliefs that foster optimism; 3) promoting consistent engagement with treatment; and 4) fostering positive therapeutic relationships.