Study Suggests Clinically Meaningful Improvement Benchmark for TDIS in Tardive Dyskinesia

A newly published analysis in The Journal of Clinical Psychiatry proposed a 4-point minimal clinically important difference (MCID) for the Tardive Dyskinesia Impact Scale (TDIS), a patient-reported outcome measure designed to assess the physical, social, and emotional burden of tardive dyskinesia (TD). Using data from Neurocrine’s valbenazine (Ingrezza) KINECT clinical program, the analysis was intended to help interpret patient-reported change alongside clinician-rated movement severity.^1,2

“The observable severity of tardive dyskinesia movements does not always reflect the full burden patients endure in their daily lives,” Sanjay Keswani, MD, chief medical officer of Neurocrine Biosciences, said in a statement.¹ “This publication reinforces the importance of assessing patients’ personal experience alongside clinician-rated movement severity to better understand treatment response.”

The TDIS is an 11-item instrument assessing 6 domains: mouth/throat, dexterity, mobility, pain, social functioning, and emotional functioning. According to Neurocrine, the new publication builds on prior psychometric validation by defining a threshold for clinically meaningful improvement in total score. The company reported that across the KINECT 3 (NCT02274558) and KINECT 4 (NCT02405091) studies, reductions in TDIS burden corresponded with improvements in clinician-rated movement severity and global assessments.

For context, valbenazine is a selective vesicular monoamine transporter 2 (VMAT2) inhibitor approved by the FDA for adults with TD and for chorea associated with Huntington disease.³ In KINECT 3, a previously completed trial, valbenazine was evaluated in adults with moderate or severe TD and showed significant improvement in Abnormal Involuntary Movement Scale scores at 6 weeks compared with placebo, supporting its regulatory approval for TD.⁴ According to the study authors, the newly published TDIS analysis does not change the approved indication but may provide clinicians and investigators with a more interpretable patient-reported benchmark for trial outcomes.

READ MORE: Survey of Neurologists and Psychiatrists Reveals Barriers to Optimal Tetrabenazine Use

TD remains a clinically challenging drug-induced movement disorder associated most commonly with dopamine receptor–blocking agents, including antipsychotics, and with some gastrointestinal agents such as metoclopramide and prochlorperazine. Symptoms may involve the face, tongue, trunk, and extremities and can persist despite medication changes. Neurocrine noted that it estimates at least 800,000 adults in the United States are affected by the movement disorder.¹

The KINECT-PRO phase 4 study, also described in the company announcement, was an open-label study designed to evaluate patient-reported outcomes in a TD population intended to resemble real-world practice. Participants had at least mild TD, awareness of abnormal involuntary movements, at least mild distress related to those movements, and a diagnosis of schizophrenia, schizoaffective disorder, bipolar disorder, or major depression. Patients received valbenazine 40 mg once daily for 4 weeks, followed by flexible dosing of 40, 60, or 80 mg once daily for 24 weeks, with a 2-week safety follow-up.

The most common adverse reactions listed for valbenazine in TD are somnolence and fatigue. The prescribing information also warns about hypersensitivity reactions including angioedema, QT prolongation, neuroleptic malignant syndrome, parkinsonism, and, in patients with Huntington disease, depression and suicidality.³ These risks remain relevant when interpreting patient-reported benefit, particularly because many patients with TD have psychiatric comorbidities and receive concomitant psychotropic medications.

From a clinical standpoint, the proposed 4-point MCID may help contextualize whether a statistically significant TDIS change is meaningful to patients. However, the threshold was derived in a valbenazine clinical development program, and broader validation across independent cohorts, different TD severities, and other treatment strategies would strengthen generalizability. Open-label patient-reported studies are also susceptible to expectation and ascertainment bias, making blinded and longitudinal validation important next steps.

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REFERENCES
1. Neurocrine Biosciences announces publication establishing clinically meaningful improvement threshold for the Tardive Dyskinesia Impact Scale. News release. Neurocrine Biosciences. April 29, 2026. Accessed May 20, 2026. https://neurocrine.gcs-web.com/news-releases/news-release-details/neurocrine-biosciences-announces-publication-establishing
2. Bron M, Mathias SD, Stull DE, et al. Measuring What Matters: Further Validation for the Tardive Dyskinesia Impact Scale, a Novel Patient-Reported Outcome Measure in Valbenazine Clinical Trials. J Clin Psychiatry. 2026;87(2):25nr16047. Published 2026 Apr 29. doi:10.4088/JCP.25nr16047
3. Neurocrine Biosciences Announces FDA Approval of INGREZZA® (valbenazine) Capsules for the Treatment of Chorea Associated With Huntington's Disease. News release. Neurocrine Biosciences. August 18, 2023. Accessed May 20, 2026. https://neurocrine.gcs-web.com/news-releases/news-release-details/neurocrine-biosciences-announces-fda-approval-ingrezzar
4. Hauser RA, Factor SA, Marder SR, et al. KINECT 3: A Phase 3 Randomized, Double-Blind, Placebo-Controlled Trial of Valbenazine for Tardive Dyskinesia. Am J Psychiatry. 2017;174(5):476-484. doi:10.1176/appi.ajp.2017.16091037