Low Sustainment of High-Dose Oral Medication Regimens for Advanced Parkinson's Disease in Medicare Beneficiaries.

Background: Increasing doses of oral antiparkinson medications are indicated in advanced Parkinson's disease (PD), but little is known about sustainment of high-dose regimens.

Objective: To investigate sustainment of high-dose oral medication regimens in Medicare beneficiaries with incident advanced PD.

Methods: This retrospective cohort study utilized 100%fee-for-service Medicare claims from 2011-2013. We identified advanced PD using a pharmacy claims-based proxy and selected patients who initiated a new high-dose oral medication regimen (daily levodopa equivalent dose [LED] >1000 mg/day for ≥30 days) in 2012. In the following 12 months, we examined: 1) annual proportion of days covered (PDC)≥0.80 and 2) presence of a ≥ 90 day continuous gap at varying dosage thresholds: the initial >1000 mg/day, >800 mg/day, >500 mg/day, or >0 mg/day.

Results: We identified 9,405 patients with advanced PD (mean age 77.4 [SD 6.8] years; 53%men). Only 5%maintained a regimen of >1000 mg/day at PDC ≥0.80; 75% had a ≥ 90-day gap in that dosage level. At a dosage threshold of >800 mg/day, 20% had a PDC ≥0.80 and 53% had a ≥ 90-day gap; at >500 mg/day, 56% had a PDC ≥0.80 and 19%had a ≥ 90-day gap; and at >0 mg/day (any dose), 76% had a PDC ≥0.80 and only 10%had a≥90-day gap.

Conclusion: Few patients with advanced PD sustained a high-dose oral medication regimen in the year following initiation, but most sustained a substantially lower-dose regimen. Strategies to improve advanced PD treatment are needed.