Drug therapies for Parkinson's disease: A database analysis of patient compliance and persistence.

BACKGROUND: Evaluating medication adherence in Parkinson's disease (PD) is important to avoid erroneously attributing suboptimal patient outcomes from poor compliance to disease progression or adverse responses to medications.
OBJECTIVE: This study of patients with PD who were new to PD drug therapy examined patient compliance and persistence, by drug, to provide a comprehensive investigation of medication-taking behavior in PD.
METHODS: A retrospective analysis of patients receiving a new PD drug between March 1 and May 31, 2007, was conducted, using the IMS Health longitudinal prescription database, which contains ∼50% of all retail prescriptions and <150 million patients in the United States. Patients were considered to have received a new PD drug if they initiated PD therapy for the first time, added adjunctive PD therapy, or switched one PD drug for another. Patients were categorized as naive to PD therapy (NT) or having prior PD therapy (PT), which included adjunctive use and switches. The PD medications evaluated were rasagiline, levodopa/carbidopa, levodopa/carbidopa/entacapone, the catechol-O-methyltransferase (COMT) inhibitors (entacapone and tolcapone), pramipexole, ropinirole, and selegiline. The study consisted of a 12-month look-back period (during which patients were required to be active in the database), a 3-month selection period (during which patients received their first prescription), and a 12-month observation period. Compliance was measured using the medication possession ratio (MPR; defined as the number of days' supply of medication divided by the number of available days of therapy, from first dispense date in the selection period to last dispense date in the observation period); noncompliance was defined as an MPR ≤80%. Persistence was measured as the duration (days) of uninterrupted therapy.
RESULTS: A total of 29,682 patients with PD (19,673 NT, 10,009 PT) received a new PD drug and were analyzed. Of the 19,510 patients included in the compliance analysis, 10,438 (53.5%) had compliance rates >80% and 9072 (46.5%) were noncompliant. For all patients (NT and PT), compliance rates were significantly higher for patients taking rasagiline than for those taking other PD medications (all P < 0.001). For all patients, the highest mean number of persistent days of treatment (147.5) was reported for rasagiline, followed by levodopa/carbidopa/ entacapone (146.9); persistence for both of these drugs was significantly higher than that for the comparator medications (rasagiline vs levodopa/carbidopa, P = 0.002; rasagiline vs pramipexole, P = 0.003; rasagiline vs COMT inhibitors, ropinirole, and selegiline, all P < 0.001; levodopa/carbidopa/entacapone vs levodopa/carbidopa, P = 0.005; levodopa/carbidopa/entacapone vs pramipexole, P = 0.006; levodopa/carbidopa/entacapone vs COMT inhibitors, ropinirole, and selegiline, all P < 0.001). Almost half of the patients (13,103; 44.1%) remained on their PD medication ≥90 days.
CONCLUSIONS: This study found a differential compliance and persistence across PD drug therapies. The compliance rate for rasagiline was significantly higher than that for all of the other PD medications. In addition, rasagiline and levodopa/carbidopa/entacapone were associated with significantly higher persistence rates than were the other PD medications.