Complex Bodily Hallucinatory Experiences Scale (CBHES): Development, structure and psychometric properties.

Objectives: Complex bodily hallucinations are not rare in psychiatric, neurological and toxicological conditions and may also be reported even in the total absence of any medical condition. Despite this, they are usually not clinically assessed independently from (and in comparison to) hallucinations in other modalities. The objective of this study was to develop a short scale assessing complex bodily hallucinations.

Methods: Based on previous research and clinical reports, we present a new short scale for the assessment of four themes of such hallucinations, i.e., delusional parasitosis, the feeling of presence, autoscopic phenomena, and body distortions. The scale was completed by 623 participants from the general population.

Results: Complex bodily hallucinations are frequent, with 96.6% of the sample reporting at least one. A Confirmatory Factor Analysis showed that the data best fit a hierarchical model in which the four independent themes are linked to a higher-order factor that we tentatively identifed as bodily self-consciousness. Each one of the four themes was reported in isolation in less than 5% of the sample, but combinations of themes were more frequent. The scale has good internal consistency, a good 3-month test-retest reliability, and good convergent validity. Furthermore, the scale has a good balance between specificity and sensitivity when the 90^th percentile of the total score is used as a classification criterion.

Conclusion: The short scale developed has good psychometric properties and can be used both in clinical and research settings.