Abnormal involuntary movement scale in tardive dyskinesia: Minimal clinically important difference.

Abstract

BACKGROUND:

A minimal clinically important difference has not been established for the Abnormal Involuntary Movement Scale in patients with tardive dyskinesia. Valbenazine is a vesicular monoamine transporter 2 inhibitor approved for the treatment of tardive dyskinesia in adults. Efficacy in randomized, double-blind, placebo-controlled trials was defined as the change from baseline in Abnormal Involuntary Movement Scale total score (sum of items 1-7).

OBJECTIVES:

To estimate an minimal clinically important difference for the Abnormal Involuntary Movement Scale using valbenazine trial data and an anchor-based method.

METHODS:

Data were pooled from three 6-week double-blind, placebo-controlled trials: KINECT (NCT01688037), KINECT 2 (NCT01733121), and KINECT 3 (NCT02274558). Valbenazine doses were pooled for analyses as follows: "low dose," which includes 40 or 50 mg/day; and "high dose," which includes 75 or 80 mg/day. Mean changes from baseline in Abnormal Involuntary Movement Scale total score were analyzed in all participants (valbenazine- and placebo-treated) with a Clinical Global Impression of Change-Tardive Dyskinesia or Patient Global Impression of Change score of 1 (very much improved) to 3 (minimally improved).

RESULTS:

The least squares mean improvement from baseline to week 6 in Abnormal Involuntary Movement Scale total score was significantly greater with valbenazine (low dose: -2.4; high dose: -3.2; both, P < 0.001) versus placebo (-0.7). An minimal clinically important difference of 2 points was estimated based on least squares mean changes in Abnormal Involuntary Movement Scale total score in participants with a Clinical Global Impression of Change-Tardive Dyskinesia score ≤3 at week 6 (mean change: -2.2; median change: -2) or Patient Global Impression of Change score ≤3 at week 6 (mean change: -2.0; median change: -2).

CONCLUSIONS:

Results from an anchor-based method indicate that a 2-point decrease in Abnormal Involuntary Movement Scale total score may be considered clinically important. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

• Authors: Mark Stacy, Martha Sajatovic, John M Kane, Andrew J Cutler, Grace S Liang, Christopher F O'Brien, Christoph U Correll
• Journal: Movement disorders : official journal of the Movement Disorder Society (Mov Disord) Vol. 34 Issue 8 Pg. 1203-1209 (08 2019) ISSN: 1531-8257 [Electronic] United States
• PMID: 31234240 (Publication Type: Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)
• Copyright: © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Chemical References

• Antipsychotic Agents
• Vesicular Monoamine Transport Proteins
• valbenazine
• Valine
• Tetrabenazine

Topics

• Aged
• Antipsychotic Agents (adverse effects)
• Female
• Humans
• Male
• Middle Aged
• Minimal Clinically Important Difference
• Mood Disorders (drug therapy)
• Psychotic Disorders (drug therapy)
• Schizophrenia (drug therapy)
• Tardive Dyskinesia (drug therapy, etiology, physiopathology)
• Tetrabenazine (analogs & derivatives, therapeutic use)
• Treatment Outcome
• Valine (analogs & derivatives, therapeutic use)
• Vesicular Monoamine Transport Proteins (antagonists & inhibitors)