The reliability of three definitions of bizarre delusions.

OBJECTIVE

This study was conducted to determine whether the interjudge reliability of the DSM-III-R concept of bizarre delusions could be improved by alternative definitions of the concept.

METHOD

Twelve raters evaluated 180 delusions of separate psychiatric patients according to the DSM-III-R and two alternative definitions of bizarre delusions.

RESULTS

The kappas for the DSM-III-R definition and for one of the alternative definitions were 0.64 and 0.65, respectively; for the other alternative definition it was 0.45. All three definitions were highly intercorrelated, largely identifying the same cases.

CONCLUSIONS

Neither of the alternative definitions of bizarre delusions was more reliable than the DSM-III-R definition. The reliability of the DSM-III-R definition, although only fair, is comparable to that of other important clinical concepts that play a major role in the DSM-III-R diagnostic criteria for psychotic disorders.