Systemically treated breast cancer patients and controls: an evaluation of the presence of noncredible performance.

Abstract

This study sought to define the frequency of noncredible performance in breast cancer patients before, during and after completion of systemic treatment, as well as predictors of noncredible performance. We examined six datasets investigating the cognitive effects of chemotherapy and/or endocrine therapy. Embedded performance validity test (PVT) measures were identified and used to evaluate the datasets. One dataset included a standalone PVT. Possible noncredible performance was operationally defined as performance below criterion on three or more PVT indices. This was undertaken as cancer patients have been observed clinically to fail PVTs both in the context of external gain and independent of such motivators. A total of 534 breast cancer patients and 214 healthy controls were included in the analysis. Percentages of patients performing below cutoff on one or more PVT varied from 0% to 21.2%. Only 1 patient met the criterion of noncredible performance. Calculation of post-test probabilities indicated a more than 90% chance to detect noncredible performance. There is no evidence to suggest noncredible performance in breast cancer patients and healthy controls who choose to participate in research studies examining cognitive function. Thus, the observational data showing that non-central nervous system (CNS) cancer and therapies not targeting the CNS can have untoward effects on cognitive function are unlikely to be due to noncredible performance.