We examine symptom and performance validity in psychological assessments of regularly referred hospital outpatients.
Over-reporting of symptoms occurred in 12–19% in the main diagnostic groups.
Morbid obese patients, screened for eligibility for gastric bypass surgery, had a low rate of symptom over-reporting (1%).
Poor symptom and performance validity are related to performance on standard psychological measures.
Standard incorporation of validity tests in clinical assessments of hospital outpatients is recommended.