Neurocrine Biosciences Inc. (NASDAQ: NBIX) announced the publication of research in The Journal of Clinical Psychiatry that establishes a clinically meaningful improvement threshold for the Tardive Dyskinesia Impact Scale.

The research defines a minimal clinically important difference of four points for the TDIS total score, providing guidance for interpreting results from clinical trials of INGREZZA (valbenazine) capsules. The scale measures physical and functional impairment along with socio-emotional distress associated with involuntary movements in tardive dyskinesia patients.

The publication analyzed data from the KINECT 3 and KINECT 4 studies, where TDIS captured reductions in the physical, social and emotional impact of tardive dyskinesia that corresponded with improvements in clinician-rated movement severity assessments.

"The observable severity of tardive dyskinesia movements does not always reflect the full burden patients endure in their daily lives," said Sanjay Keswani, Chief Medical Officer at Neurocrine Biosciences.

The Tardive Dyskinesia Impact Scale was developed by Neurocrine in partnership with neurology and psychiatry specialists and represents the first psychometrically validated patient-reported outcome measure designed specifically for tardive dyskinesia. The scale consists of 11 questions evaluating six areas: mouth/throat, dexterity, mobility, pain, social and emotional impact.

The findings also support previously reported results from KINECT-PRO, a Phase 4 study that evaluated patient-reported outcomes with INGREZZA treatment. Tardive dyskinesia affects an estimated 800,000 adults in the United States and is characterized by uncontrolled, repetitive movements associated with certain mental health medications.