Screening for malingered mental illness in a court clinic

We examined 97 criminal defendants who were consecutively referred to a court-appointed psychologist. Based on an interview and any available records, a psychologist rated the severity of each defendant's mental disorder (if any) as well as the likelihood that he or she was malingering psychiatric symptoms. Eleven (11.3%) of the defendants were judged to be likely or very likely malingering. Following the clinical evaluation, each defendant completed two screening tests of malingering. As expected, the suspected malingerers failed more items on a forced-choice vocabulary test and endorsed more implausible symptoms of schizophrenia than presumed honest defendants. Also as hypothesized, an index that combined the scores of both measures distinguished subject groups more accurately than either test alone. The optimal cutoff score for this Malingering Index yielded a positive predictive value of 88% and a negative predictive value of 96%.