The Clinician’s Tardive Inventory (CTI): A New Clinical Tool for Documenting and Rating Tardive Dyskinesia

Objective: Current clinician-rated tardive dyskinesia (TD) symptom scales have not addressed the expanding clinical signs and functional impact of TD. The study objective was to develop and test the reliability of a new integrated instrument. Methods: A movement disorder neurologist devised the outline of the rating scale. A Steering Committee (5 neurologists and 2 psychiatrists) provided revisions until consensus was reached. The Clinician’s Tardive Inventory (CTI) assesses abnormal movements of the eye/eyelid/face, tongue/mouth, jaw, and limb/trunk; complex movements defined as complicated movements different from simple patterned movements or postures; and vocalizations. The CTI rates frequency of symptoms from 0 to 3 (ranging from absent to constant). Functional impairments, including activities of daily living (ADL), social impairment, symptom distress, and physical harm, are rated 0–3 (ranging from unawareness to severe impact). The CTI underwent interrater and test-retest reliability testing between February and June 2022 based on videos and accompanying vignettes, which were reviewed by 2 movement disorder specialists to determine adequacy. Four clinicians rated each video/vignette. Interrater agreement was analyzed via 2-way random-effects intraclass correlation (ICC), and test-retest agreement was assessed utilizing the Kendall tau-b. Results: Forty-five video/vignettes were assessed for interrater reliability and 16 for test-retest reliability. The most prevalent movements were those of the tongue and mouth (77.8%) and jaw (55.6%). ICCs for movement frequency for anatomic symptoms were as follows: anatomic symptom summary score 0.92, abnormal eye movement 0.89, abnormal tongue/mouth movement 0.91, abnormal jaw movement 0.89, abnormal limb movement 0.76, complex movement 0.87, and abnormal vocalization 0.77; ICCs for functional impairments were as follows: total impairment score 0.92, physical harm 0.82, social embarrassment 0.88, ADLs 0.83, and symptom bother 0.92; Retests were conducted a mean (SD) of 15 (3) days later with correlation coefficients ranging from 0.66 to 0.87. Conclusions: The CTI is a new integrated instrument with proven reliability in assessing TD signs and functional impacts. Future validation study is warranted.