Austedo Adherence Rates Higher Than Xenazine’s, US Study Finds
The study also found lower discontinuation rates with Austedo, which may suggest that, between these two treatments for chorea, Austedo tends to be better tolerated.
“Real-World Adherence to Tetrabenazine or Deutetrabenazine Among Patients With Huntington’s Disease: A Retrospective Database Analysis,” was published in Neurology and Therapy. It was sponsored by Teva Pharmaceuticals, which markets Austedo.
Chorea, or involuntary, abrupt movements, is one of the hallmark symptoms of Huntington’s. Austedo and Xenazine (by Lundbeck Pharmaceuticals) both are approved to treat Huntington’s-associated chorea in the U.S.
These two medications work in the same way, by reducing the release of a signaling molecule called dopamine from nerve cells, thereby reducing abnormal movements.
Due to pharmacological differences between them, however, Austedo leads to more consistent exposure to the medication throughout the body, allowing for less frequent dosing, the study reported. Pharmacological differences may also give Austedo a better safety/tolerability profile than Xenazine.
But little real-world data exists that compares the two medicines.
A team of six researchers — including two with Teva and three with an analysis group — used U.S. insurance data to investigate patterns in adherence between the two medications. “Adherence” basically means taking a medication as directed.
The database used, the Symphony Health Solutions’ Integrated Dataverse, “captures approximately 90% of all prescription claims filled at US retail pharmacies, representing over 75% of the United States population,” the researchers wrote.
In the database, the team identified 281 Huntington’s patients who started treatment with Austedo between 2017 and 2019. For comparison, they also identified 101 patients who had started on Xenazine in that time.
The two groups were demographically similar — most patients were 38 to 65 years old, and over half were female. However, more patients in the Austedo than Xenazine group had commercial insurance, while patients on Xenazine were more commonly insured through Medicaid. In addition to Austedo/Xenazine, many patients also were being treated with other medicines, like antidepressants or antipsychotics.
Researchers assessed adherence rates by calculating the proportion of days covered, or PDC, based on when prescriptions were filled. As a simple example, if a patient got 30 days’ worth of a medicine, then refilled the prescription after 35 days, then the PDC is 30 out of 35, or about 86%.
Results of the analysis showed that PDC was significantly higher with Austedo compared with Xenazine (78.5% vs. 69.3%). The proportion of patients with a PDC higher than 80% was also higher in the Austedo group, though the difference was not statistically significant.
Further statistical analyses indicated that, within the Austedo group, adherence was more common among patients insured through Medicare compared with those with commercial insurance. Compared with nonadherent patients, adherent ones tended to start treatment later, had longer disease duration, and shorter duration of follow-up. They also were more likely to use antidepressants, anticonvulsants, anti-anxiety medications, and fat-lowering medicines.
The proportion of patients who discontinued the respective treatment in the six months after the first month of treatment was significantly lower in the Austedo than Xenazine group (25.4% vs. 37.2%), with similar differences at briefer time points.
“Results from this real-world analysis using data from a large United States claims database has shown that patients with HD [Huntington’s disease] in the deutetrabenazine [Austedo] cohort had greater adherence and lower discontinuation rates compared to patients in the tetrabenazine [Xenazine] cohort,” the scientists concluded.
The team added that these differences “may reflect differences in dosing regimen and tolerability profiles,” though they noted a need for further investigation into factors underlying differences in adherence.
A noted study limitation, according to the scientists, was the use of insurance data, which is necessarily less precise than clinical information. The team also noted that evaluating when prescriptions are filled cannot, by definition, provide definitive information about when and whether patients actually took the medications.