Sensitivity and specificity of reliable digit span in malingered pain-related disability.

The reliable digit span (RDS) performance of chronic pain patients with unambiguous spinal injuries and no evidence of exaggeration or response bias (n = 53) was compared to that of chronic pain patients meeting criteria for definite malingered neurocognitive dysfunction (n = 35), and a group of nonmalingering moderate-severe traumatic brain injury (TBI) patients (n = 69). The results demonstrated that scores of 7 or lower were associated with high specificity (> .90) and sensitivity (up to .60) even when moderate to severe TBI are included. Multiple studies have demonstrated that RDS scores of 7 or lower rarely occur in TBI and pain patients who are not intentionally performing poorly on cognitive testing. This study supports the use of the RDS in detecting response bias in neuropsychological patients complaining of pain as well as in the assessment of pain-related cognitive impairment in patients whose primary complaint is pain.