Measuring What Matters

Tardive dyskinesia (TD) is a persistent, potentially disabling, medication-induced movement disorder that has been underrecognized. Involuntary movements in TD have a substantial impact beyond movement on individuals with TD. To quantify TD impact and burden, the Tardive Dyskinesia Impact Scale (TDIS), a new, TD-specific, fit-for-purpose patient-reported outcome (PRO) measure, was developed. Objectives were to examine how TDIS contributes to understanding of TD burden and use of clinician-reported outcomes (ClinROs) and other PROs in clinical trials assessing effects of vesicular monoamine transporter 2 inhibitors on TD. TDIS analyses included assessment of correlations between TDIS and other clinical outcome assessments (PROs and ClinROs), estimation of the minimal clinically importance difference (MCID), and description of the change in TDIS individual items longitudinally and via item response theory. =0.34) scores. TDIS is the only disease-specific PRO that has been validated in individuals with TD and complements ClinROs and other PROs by providing a comprehensive picture of TD impact beyond movement symptoms and can measure potential benefit of TD treatments.