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.
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