A latent class analysis of positive psychosis symptoms based on the British Psychiatric Morbidity Survey

This study aimed to describe the distribution of positive psychosis symptoms in a large scale, population-based sample. Data from the British Psychiatric Morbidity Survey was used to examine homogeneous sub-types of participants based on their responses to the five probe items of the Psychosis Screening Questionnaire. Latent class analysis was used to identify the underlying class structure of psychosis. Four classes of psychosis were identified. Associations between the latent classes and the demographic risk factors, clinical variables and reports of traumatic experiences showed significantly higher risks for the psychosis class, the paranoid class, and the intermediate class compared to the normative class. Four classes that appeared to represent an underlying continuum could best explain psychosis symptom expression at the population level.