Dopamine Transporter Brain Imaging to Assess the Effects of Pramipexole vs Levodopa on Parkinson Disease Progression

To compare rates of dopamine neuron degeneration after initial treatment with pramipexole or levodopa in early PD by means of dopamine transporter imaging using single-photon emission computed tomography (SPECT) with 2beta-carboxymethoxy-3beta(4-iodophenyl)tropane (beta-CIT) labeled with iodine 123.

Substudy of a parallel-group, double-blind randomized clinical trial. SETTING AND PATIENTS: Eighty-two patients with early PD who were recruited at 17 clinical sites in the United States and Canada and required dopaminergic therapy to treat emerging disability, enrolled between November 1996 and August 1997. INTERVENTIONS: Patients were randomly assigned to receive pramipexole, 0.5 mg 3 times per day with levodopa placebo (n = 42), or carbidopa/levodopa, 25/100 mg 3 times per day with pramipexole placebo (n = 40). For patients with residual disability, the dosage was escalated during the first 10 weeks, and subsequently, open-label levodopa could be added. After 24 months of follow-up, the dosage of study drug could be further modified. MAIN OUTCOME MEASURES: The primary outcome variable was the percentage change from baseline in striatal [(123)I]beta-CIT uptake after 46 months. The percentage changes and absolute changes in striatal, putamen, and caudate [(123)I]beta-CIT uptake after 22 and 34 months were also assessed. Clinical severity of PD was assessed using the Unified Parkinson Disease Rating Scale (UPDRS) 12 hours off anti-PD medications.