CLINICAL VALIDITY OF THE JAPANESE VERSION OF PDI (PETERS ET AL. DELUSIONS INVENTORY)
 
Syudo, Y., Iwanami, A., Morimoto, S., Tanno, Y. and Tsujii, K., University of Tokyo, Japan
 
Objective: PDI (Peters et al. Delusions Inventory: Peters et al. 1999) was designed to measure delusional ideation in the normal population, using the Present State Examination (Wing et al. 1974) as a template. PDI is self- rating scales for delusional ideations. We translated PDI into Japanese language and tested the clinical utility of it. Methods: The Japanese version of PDI was consisted of 40 items which was including assessing measures of distress, preoccupation and conviction for each item. PDI was administered to 204 college students and 19 schizophrenic patients. PDI was readministered to 126 college students after 2 weeks in order to examine the test-retest reliability. Clinical symptoms were evaluated by medical staff (psychiatrists, nurses, occupational therapists and clinical psychologists) using Brief Psychiatric Rating Scale (BPRS: Overall and Gorham 1962). Results: Good internal consistency (f=0.89) and test-retest reliability (r=.81) were obtained. The PDI score was significantly correlated with some BPRS items (suspiciousness (r=.50 p<05), unusual thought content (r=.42 p<10) and guilt feelings (r=.45 P<10)). But the PDI score was not significantly correlated with other BPRS items. Schizophrenic patients had significantly higher scores in distress and preoccupation. Conclusions: The Japanese version of PDI possesses enough reliability and clinical validity. The normal population and schizophrenic patients were differentiated by their ratings on the distress and preoccupation.