Limited Prediction of Performance Validity Using Embedded Validity Scales of the Neurobehavioral Symptom Inventory in an mTBI Veteran Sample.

OBJECTIVE: To test embedded symptom validity scales of the Neurobehavioral Symptom Inventory (NSI) as predictors of performance validity. SETTING: A Veterans Affairs Level II TBI/Polytrauma outpatient care unit in the Midwestern United States. PARTICIPANTS: Veterans with a history of mild traumatic brain injury undergoing neuropsychological assessment as part of their routine care within the TBI/Polytrauma clinic. DESIGN: Retrospective analysis of the existing clinical data. MAIN MEASURES: The NSI, the b Test, Test of Memory Malingering, Reliable Digit Span, California Verbal Learning Test-II Forced Choice. RESULTS: Embedded NSI validity scales were positively correlated with number of performance validity test failures. Participants identified as invalid responders scored higher on embedded NSI validity scales than participants identified as valid responders. Using receiver operating characteristic analysis, the embedded NSI validity scales showed poor sensitivity and specificity for invalid responding using previously published cutoff scores. Only 1 scale differentiated valid from invalid responders better than chance. CONCLUSION: The embedded NSI validity scales' usefulness in predicting invalid neuropsychological performance validity was limited in this sample. Continued measurement of both symptom and performance validity in clinical settings involving traumatic brain injury treatment is recommended, as the present results support the existing research suggesting symptom validity tests and performance validity tests tap into related but ultimately distinct constructs.

The cost of medical education.

As the result of another study which identified the indirect costs at a large teaching hospital in which Monash University has established a clinical school, it has been possible to estimate the cost per annum for each medical student. This is the sum of direct university costs ($4,617), Tertiary Education Assistance Scheme ($1,200) and indirect costs ($44)--in aggregate therefore $5,900 (rounded). Thus the cost of the six-year course for each student is approximately $35,500.

Hospital costs--the medical student component.

A study of indirect costs which could be attributed to undergraduate teaching in a large affiliated teaching hospital has shown that they are very small. Thus direct university costs in 1975 were $1,800,000 (7-6% of all expenditure at the hospital); indirect costs were $41,000 (approximately 0-2% of the hospital expenditure). It is concluded that the 45% difference in bed costs per day between teaching and non-teaching hospitals from a previous investigation is therefore not the result of the clinical school indirect demands on hospital expenditure.

Hospital staffing and hospital costs.

A comparative study of costs per bed per day in teaching hospitals affiliated with Monash University compared with large non-teaching metropolitan hospitals (1964 to 1974) shows they are much higher in teaching hospitals. There is no evidence that this is due to the additional costs arising from the clinical schools. Research in the teaching hospitals and the accompanying high professional standards and demands on services are major factors accounting for the difference. Over the decade studied, the resident staff have increased by 77% and other salaried staff by 24%. The index of expenditure for the three teaching hospitals in the decade has increased by 386%.

Medical manpower-the Australian scene.

Medical manpower projections indicate that by 1991 there will be one doctor to 500 population instead of the 1: 721 ratio in 1976. There are many variables; projections, while hazardous, are necessary for planning because of the long lead time. Productivity is equally important. There is no evidence that the rapidly rising female intake will reduce productivity in the next 15 years.