Interrater reliability of ratings of delusions and bizarre delusions

Objective: The authors evaluated the interrater reliability of ratings of bizarre delusions, addressing limitations of previous studies. Method: Fifty randomly selected psychiatrists rated bizarre delusions in 30 case vignettes adapted from a previous study by Spitzer and associates. Estimates of reliability were obtained for definitions of bizarre delusions in the DSM- III, DSM-III-R, and draft DSM-IV criteria for schizophrenia and for the clinicians grouped according to their current and previous experience with psychotic patients. Results: The kappas for ratings of bizarre delusions according to the different definitions and among clinicians with different levels of experience were in the moderate to fair range. Conclusions: The reliability of ratings of bizarre delusions appears to be less than satisfactory for clinical practice, and the increased weight given to this symptom in modern diagnostic systems does not seem justifiable.