A survey of delusional ideation in primary-care patients

Background. To assess the prevalence of delusional ideas in primary-care patients. Method. A survey was carried out with the Aquitaine Sentinel Network of general practitioners (GPs). Consecutive practice attenders were invited to complete the Peters et al. Delusional Inventory (PDI-21) self-report questionnaire, designed to measure delusional ideation in the normal population. GPs, blind to the questionnaire results, provided information on patients' psychiatric history. Results. Of the 1053 attenders included in the survey, 348 (35%) had a lifetime history of psychiatric disorder, of whom 20 (2%) had a history of broadly defined psychotic disorder. The self-report questionnaire was completed by 790 patients. The range of individual PDI-21 item endorsement in subjects with no psychiatric history varied between 5 and 70%, suggesting that delusional ideation is a dimensional phenomenon lying on a continuum with normality. The main discriminative items between psychotic and non-psychotic patients were those exploring persecutory (OR=15·2, 95% CI 4·3–53·7), mystic (OR=6·4, 95% CI 1·9–22·4) and guilt (OR=5·8, 95% CI 1·5–23·2) ideas. Conclusions. This survey demonstrates that questions that explore delusions and hallucinations are well-accepted by most primary-care patients. More research is needed on psychotic disorders in primary-care settings to improving early identification of these disorders.