DYSFUNCTIONAL BELIEFS AND ATTITUDES ABOUT SLEEP (DBAS -16) SCALE IN PATIENTS REFERRED TO PSYCHIATRIC OUTPATIENT CLINIC FOR SLEEP CONSULTATION IN FINLAND – A REGISTRY-BASED STUDY

Background: Dysfunctional assumptions about sleep are characteristic of chronic insomnia and an important target of treatment. The Dysfunctional Beliefs and Attitudes about Sleep (DBAS-16) scale identifies clinically significant levels of unhelpful beliefs related to sleep and differentiates insomnia patients from “non-insomnia” patients. More information is needed about DBAS measurement properties in psychiatric patients with sleep complaints. The aim of this study was to find a DBAS-16 cut-off value to identifying clinical insomnia among patients with psychiatric comorbidity to recognize patients who would benefit from Cognitive Behavioural Therapy for Insomnia (CBT-I), which is the primary evidence-based treatment for insomnia. Methods: The register-based sample comprised 115 psychiatric outpatients referred to the University Hospital Psychiatric Outpatient Clinic for Sleep Consultation, where their sleep complaints were evaluated comprehensively for symptoms and diagnosis. The DBAS scores of cases with insomnia disorder were compared with those without comorbid insomnia disorder by analysis of variance, and the optimal cut-off point was calculated using the Youden index. Results: Mean age of patients was 40.1 years (SD 12.5). DBAS of patients with insomnia disorder (mean 6.26) was significantly higher than that of non-insomnia patients (mean 5.35). Organic sleep disorders, such as sleep apnoea, restless legs syndrome and delayed sleep phase, had no independent effect on DBAS. The optimal cut-off point for discriminating insomnia in psychiatric patients was 6.3, with sensitivity of 0.64 and specificity of 0.67. Conclusions: In a psychiatric outpatient sample, the DBAS cut-off value should be set higher than in a population sample to recognize patients who would benefit from Cognitive Behavioural Therapy for Insomnia (CBT-I).