Characterizing Treatment Effects of Valbenazine for Tardive Dyskinesia: Additional Results From the KINECT 3 Study.

BACKGROUND: In the KINECT 3 (NCT02274558; October 2014 to September 2015) study, valbenazine efficacy in tardive dyskinesia (TD) was demonstrated based on mean changes from baseline in the Abnormal Involuntary Movement Scale (AIMS) total score (sum of items 1-7). Data from this study were analyzed further to provide a more clinically meaningful interpretation of the primary AIMS results.

METHODS: The study included adults who had a DSM-IV diagnosis of schizophrenia, schizoaffective disorder, or any mood disorder and also met DSM-IV criteria for neuroleptic-induced TD. Study participants received 6 weeks of double-blind treatment with valbenazine (40 or 80 mg/d) or placebo. Post hoc AIMS analyses, based on available data, included Cohen d effect sizes, response analyses with odds ratios (ORs) and numbers needed to treat (NNTs), and shift analyses.

RESULTS: At week 6 (N = 202), medium-to-high effect sizes were found for mean improvements in AIMS total score (40 mg/d, d = 0.52; 80 mg/d, d = 0.89). For AIMS total score responses of ≥ 10% to ≥ 70% improvement from baseline, statistical significance was found for valbenazine 80 mg/d versus placebo (P ≤ .01), with ORs (range, 3.0-10.3) and NNTs (range, 3-9) indicating clinical relevance. For response per AIMS item (score ≤ 1 at week 6), significant differences between valbenazine (both doses or 80 mg/d) and placebo were found in the lips, jaw, tongue, and upper extremities. In participants who had an AIMS item score ≥ 1 at baseline, the percentage with a ≥ 1-point improvement at week 6 (shift) was significantly higher with valbenazine (40 and/or 80 mg/d) versus placebo in all 7 body regions.

CONCLUSIONS: Consistent with primary published results for KINECT 3, these supplemental analyses indicate that participants treated with valbenazine (40 or 80 mg/d) had statistically significant and clinically relevant improvements in TD severity both overall and in specific body regions.

TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02274558.