Methods of Detecting Malingering and Estimated Symptom Exaggeration Base Rates in Australia

Neuropsychology malingering base rates have not been widely investigated in Australia. Estimates in North America vary with as many as 4 in 10 people evaluated for personal injury or compensation cases suspected of exaggerating symptoms. Data on Australian neuro-psychology symptom exaggeration base rates were estimated using a modified and expanded version of a survey previously designed for this purpose (Mittenberg, Patton, Canyock, & Condit, 2002). Figures were based on an estimated 1818 annual cases involved in personal injury (n = 542), disability (n = 109), criminal (n = 108), or medical (n = 1059) matters. Symptom exaggeration base rates associated with referral type and diagnoses were variable. Specifically, 17% of criminal, 13% of personal injury, 13% of disability or workers compensation, and 4% of medical or psychiatric cases were reported to involve symptom exaggeration or probable symptom exaggeration. The highest rates of symptom exaggeration included cases referred for mild head injury (23%), pain or somatoform disorders (15%), moderate to severe head injury (15%), and fibromyalgia or chronic fatigue (15%). Overall, Australian symptom exaggeration base rates reported in this study were lower compared with base rates previously reported in North America.