Background: The Abnormal Involuntary Movement Scale (AIMS) total score (sum of items 1-7) is usually the primary efficacy measure in tardive dyskinesia (TD) clinical trials. However, item 8 of the AIMS (clinician’s global impression of severity) might also be an appropriate assessment in real-life healthcare settings. To explore the potential of item 8 as a clinical measure, post hoc analyses were conducted using data from a long-term study of valbenazine, an approved TD medication.
Methods: In KINECT 4 (NCT02405091), adults with TD received once-daily valbenazine (40 or 80 mg) for 48 weeks. Analyses included two sets of AIMS item 8 scores: based on investigators’ ratings of item 8 using protocol-defined descriptors; and based on investigators’ highest scores from items 1-7 (analyzed post hoc). Shift analyses included an improvement from score ≥3 at baseline (moderate or severe) to score ≤2 at Week 48 (none to mild).
Results: At baseline in all participants (N=163), AIMS item 8 mean scores were 3.2 (protocol) and 3.3 (post hoc). In participants with a score ≥3 at baseline per investigators’ ratings using protocol-defined descriptors, 95.9% [94/98] shifted to a score ≤2 by Week 48. A similar result (93.9% [93/99]) was found when item 8 was based on investigators’ highest scores from items 1-7.
Conclusion: Shift analyses using AIMS item 8 scores indicated that most participants in KINECT 4 had a clinically meaningful improvement after 48 weeks of once-daily treatment with valbenazine. AIMS item 8 may be an appropriate clinical measure for assessing changes in TD severity.