Base rates of malingering and symptom exaggeration

Base rates of probable malingering and symptom exaggeration are reported from a survey of the American Board of Clinical Neuropsychology membership. Estimates were based on 33,531 annual cases involved in personal injury. (n=6,371), disability (n=3,688). criminal (n=1,341) or medical (n=22,131) matters, Base rates did not differ among geographic regions or practice settings, but were related to the proportion of plaintiff versus defence referrals. Reported rates would be 2-4% higher if variance due to referral source was controlled. Twenty-nine percent of personal injury, 30% of disability, 19% of criminal, and 8% of medical cases involved probable malingering and symptom exaggeration. Thirty-nine percent of mild head injury, 35% of fibromyalgia/chronic fatigue, 31% of chronic pain, 27% of neurotoxic, and 22% of electrical injury claims resulted in diagnostic impressions of probable malingering. Diagnosis was supported by multiple sources of evidence. including severity (65% of cases) or pattern (64% of cases) of cognitive impairment that was inconsistent with the condition, scores below empirical cutoff's on forced choice tests (57% of cases). discrepancies among records. self-report, and observed behavior (56%) implausible self-reported symptoms in interview (46%), implausible changes in test scores across repeated examination (45%), and validity scales on objective personality tests (38% of cases).