(B-138) Utilization of VMAT2 Inhibitors for Tardive Dyskinesia Among Adult Antipsychotic Users

Background: Tardive dyskinesia (TD) is a severe movement disorder often caused by prolonged antipsychotic use. Prevalence estimates among antipsychotic users from a 2017 meta-analysis (cross-sectional studies that reported TD rates using a standardized clinical rating scale) range from 20%-30%. The vesicular monoamine transporter 2 inhibitors (VMAT2-Is), valbenazine and deutetrabenazine, FDA-approved in 2017, are the only pharmacological treatments for TD. Tetrabenazine, a VMAT2-I approved in 2008 for other indications may be used off-label for TD. To date, real-world data on trends in TD diagnosis and VMAT2-I utilization are limited.

Objectives: To characterize trends in TD diagnoses and VMAT2-I utilization among privately insured adult (18-65 years) antipsychotic users.

Methods: This drug utilization review used U.S. private insurance data (MarketScan) from 2017-2022, analyzing adult antipsychotic users with a diagnosed mental health (MH) disorder. Annual cohorts were created, aggregated, and analyzed. TD and MH diagnoses were determined using ICD-10 codes and VMAT2-I use was identified from prescription claims. MH diagnoses were categorized hierarchically as follows: schizophrenia, bipolar disorder (BPD), major depressive disorder (MDD), and other MH disorders. Descriptive analyses summarized trends in TD diagnosis and VMAT2-I use. Multivariable logistic regression assessed predictors of VMAT2-I use, including sex, age group, hierarchical MH diagnosis group, type of antipsychotic medication, and calendar year, accounting for multiple observations within the same individual.

Results: The study included a total of 729,262 adult antipsychotic users with a diagnosed MH disorder. From 2017 to 2022, the proportion of patients with a TD diagnosis and patients using a VMAT2-I were low and increased slightly (N=849 [0.44%] in 2017; N=1,194 [0.57%] in 2022) and (N=100 [0.05%] in 2017; N=454 [0.22%]), respectively. Predictors of VMAT2-I use included use of first-generation antipsychotics compared to using only second-generation antipsychotics (adjusted odds ratio [aOR]: 2.06, 95% confidence interval [CI]: 1.59-2.67), a diagnosis of schizophrenia (aOR: 8.40, 95% CI: 6.57-10.74) or BPD (aOR: 3.18, 95% CI: 2.62-3.86), compared to those with other MH diagnoses, female sex (aOR: 1.32, 95% CI: 1.14-1.51), age 51-65 years compared to age 18-34 years (aOR: 5.57, 95% CI: 4.63-6.71), and calendar year (aOR: 1.42 95% CI: 1.36-1.48).

Conclusions: TD is diagnosed at much lower rates than expected based on prevalence estimates, suggesting underdiagnosis in clinical practice. Similarly, despite an increase in VMAT2-I treatment rates, absolute treatment rates remain low. Efforts are needed to improve TD recognition and to reduce barriers to VMAT2-I access.