Psychometric Properties of the Impairment Rating Scale in Samples of Adults With Attention Deficit Hyperactivity Disorder.

Adults with attention deficit hyperactivity disorder (ADHD) are impaired in numerous domains. However, psychometrically sound measures assessing broad-ranging impairment, particularly brief scales for diagnostic purposes, are scarce. The Impairment Rating Scale (IRS), originally developed to assess ADHD-related impairment in children, has been adapted to a 12-item self-report measure of impairment in adults. In this study, the psychometric properties of the adult IRS were examined in three samples. In Studies 1 and 2, the adult IRS demonstrated good convergent, divergent, and incremental validity among college students and an online sample of adults, respectively. In the same studies, an appropriate clinical cutoff score was identified (IRS item score ≥1) using diagnostic tests. In Study 3, the adult IRS demonstrated good interrater reliability between ratings provided by romantic partners. Overall, findings support the clinical utility of the adapted IRS for assessing the impairment diagnostic criterion for ADHD in adults.