Adherence to antiparkinson medication in a multicenter European study

Two small studies reported suboptimal therapy adherence in Parkinson's disease. We conducted a larger multicenter European study to assess medicine-taking behavior. Parkinson's disease patients taking dopaminergic therapy were enrolled in 8 centers in 5 countries, and disease severity and demographics recorded. Antiparkinson drug adherence was measured for 4 weeks using electronic monitoring bottles which record the date and time of cap opening (Aardex, Switzerland). One hundred twelve patients, mean age 65 years (standard deviation (SD) 10), with Parkinson's disease for 7.7 (SD 8.2) years completed the study. Total median adherence (doses taken/doses prescribed) was 97.7% (interquartile range [IQ] 90.6-100), days adherence (correct dose days) was 86.2% (IQ 61.1-96.2) and timing adherence (doses taken at correct time intervals) was 24.4% (IQ 5.3-56.5). Fourteen patients (12.5%) took less than 80% of prescribed doses, which was defined as suboptimal adherence. Patients with satisfactory adherence took a median of 8 mg/day (IQ 0-33) less than their prescribed dose of levodopa (P = NS), while suboptimal adherence patients took a median of 481 mg/day (IQ 205-670) less than their prescribed dose (P = 0.0006). The Parkinson motor score was significantly higher in patients with suboptimal adherence at 29 (IQ 20-40), versus those with satisfactory adherence at 19 (IQ 13-26), P = 0.005. Once daily drugs had significantly better adherence when compared with drugs prescribed more frequently (P < 0.0001). Suboptimal therapy adherence is associated with significant deviation from prescribed levodopa doses, despite greater Parkinson's motor severity. Optimizing oral medication intake has a potential role in maximizing the therapy response in Parkinson's disease.