Onset of Motor Complications and Medication Dose in Newly Diagnosed and Treated Parkinson's Disease.

Abstract

Background: Parkinson's disease (PD) patients under medical treatment experience motor complications (MCs), namely, ON/OFF fluctuations (ON/OFF) and dyskinesias.

Methods: We assessed 120 newly diagnosed PD patients after the initiation of medical treatment who were followed up for at least 24 months. We reviewed the latency of ON/OFF or dyskinesias by months and calculated the levodopa dose (LD), levodopa dose divided by daily intake (LDdiv), and levodopa equivalent dose (LED). We estimated cumulative incidence and median latency by Kaplan-Meier survival analysis. We classified patients with MCs into four groups and patients with ON/OFF or dyskinesias into three groups, according to latency.

Results: Seventy-six patients experienced MCs with a median latency of 28 months. Fifty-seven patients experienced ON/OFF and 19 experienced dyskinesias with a median latency of 28 and 50 months, respectively. The medication dose at which each patient experienced ON/OFF or dyskinesias varied widely. The median LD, LDdiv, and LED was 300 (237.5-350), 100 (79-111), and 300 (250-450) mg at the onset of MCs; 300 (200-300), 100 (83-125), and 300 (249-400) mg at the onset of ON/OFF; and 400 (375-500), 125 (105-133), and 600 (466-722.75) mg at the onset of dyskinesias, respectively. Consistently, the shortest latency group had the lowest medication dose, while the longest latency group had the highest. Five patients experienced dyskinesias before ON/OFF, with similar medication doses at the onset of ON/OFF and dyskinesias. Some patients experienced ON/OFF but have not yet developed dyskinesias under a comparable medication dose as patients who experienced dyskinesias; the latter had a significantly younger age at onset.

Conclusions: The pathophysiological backgrounds and changes causing ON/OFF or dyskinesias are not the same for all patients. The presence of ON/OFF and higher medication doses does not always cause dyskinesias. A younger age at onset may be associated with the occurrence of dyskinesias.