Minimal Clinically Important Difference in AIMS Score Based on CGIC and PGIC in Patients With Tardive Dyskinesia Treated With Deutetrabenazine

Abstract

Background

Deutetrabenazine is FDA approved for tardive dyskinesia (TD) based on two 12-week, placebo-controlled studies evaluating safety and efficacy in patients with baseline Abnormal Involuntary Movement Scale (AIMS) score ≥6. Deutetrabenazine reduced overall AIMS scores compared with placebo in ARM-TD (–3.0 vs –1.6, P=0.019) and AIM-TD (24 mg/day, –3.2 vs –1.4, P=0.003; 36 mg/day, –3.3 vs –1.4, P=0.001). This analysis assessed Minimal Clinically Important Difference (MCID) in AIMS score in patients with TD treated with deutetrabenazine.

Methods

MCID is the smallest change from baseline in AIMS score that is meaningful for patients. MCID analyses were performed based on Patient Global Impression of Change (PGIC) and Clinical Global Impression of Change (CGIC) as anchors described by Hauser et al., where MCID is the difference between patients treated with deutetrabenazine who were minimally improved and patients treated with placebo who were unchanged. Additional MCID definitions were explored: difference between patients who demonstrated treatment improvement versus those who did not (Method 2); difference between patients who demonstrated treatment success versus those who did not (Method 3).

Results

295 patients were analyzed. Based on PGIC, the suggested MCID was –2.8. Results were similar for Method 2 (75% of patients had treatment improvement; MCID = –2.8) and Method 3 (38% of patients had treatment success; MCID = –2.6). Based on CGIC, the suggested MCID was –2.6. Results were similar for Method 2 (76% of patients had treatment improvement; MCID = –2.8) and Method 3 (41% of patients had treatment success; MCID = –3.0). Therefore, the suggested MCID for deutetrabenazine is –3.

Conclusions

The MCID for change in AIMS score based on PGIC and CGIC for deutetrabenazine was –3 regardless of the analytical method. Findings suggest an AIMS score reduction of ~3 is associated with clinically meaningful improvement in TD symptoms.

Funding

Teva Pharmaceutical Industries Ltd., Petach Tikva, Israel