A single error is one too many: Examining alternative cutoffs on Trial 2 of the TOMM.

OBJECTIVE

This study investigated the potential of alternative, more liberal cutoffs on Trial 2 of the Test of Memory Malingering (TOMM) to improve classification accuracy relative to the standard cutoffs (≤44).

METHOD

The sample consisted of 152 patients (49.3% male) with psychiatric conditions (PSY) and traumatic brain injury (TBI) referred for neuropsychological assessment in a medico-legal setting (M = 44.4, M = 11.9 years). Classification accuracy for various TOMM Trial 2 cutoffs was computed against three criterion measures.

RESULTS

Patients with TBI failed TOMM Trial 2 cutoffs at higher rates than patients with PSY. Trial 2 ≤49 achieved acceptable combinations of sensitivity (0.38-0.67) and specificity (0.89-0.96) in all but one comparison group. Trial 2 ≤48 improved specificity (0.94-0.98) with minimal loss in sensitivity. The standard cutoff (≤44) disproportionally traded sensitivity (0.15-0.50) for specificity (0.96-1.00).

CONCLUSIONS

One error on TOMM Trial 2 constitutes sufficient evidence to question the credibility of a response set. However, the confidence in classifying a score as invalid continues to increase with each additional error. Even at the most liberal conceivable cutoff (≤49), the TOMM detected only about half of the patients who failed other criterion measures. Therefore, it should never be used in isolation to determine performance validity.