OBJECTIVES: Initial monotherapy for Parkinson’s disease (PD) includes carbidopa/levodopa; however, treatment approaches vary with disease progression owing to fluctuations in symptom control and increasing disability. This study describes treatment patterns in newly treated patients with PD following carbidopa/levodopa initiation.

METHODS: This retrospective study analyzed claims from a large insurance database. Patients with PD (≥1 inpatient or ≥2 outpatient claims with International Classification of Diseases, Ninth Revision, Clinical Modification [332.xx] or Tenth Revision, Clinical Modification [G20.xx, G21xx] codes) were identified. Among these patients, the index date was the date of the first observed claim for oral carbidopa/levodopa medication from 1/1/2016 to 12/31/2019. Patients were lacking carbidopa/levodopa claims during the 1-year preindex period (baseline) and continuously enrolled during baseline and ≥1 year post index (follow-up). Treatment patterns of various PD medications following initiation of carbidopa/levodopa were measured during follow-up.

RESULTS: We identified 16,531 carbidopa/levodopa treatment-naïve patients. Mean (SD) age was 75.3 (8.4) years, 40.5% were female, and 66.2% were White. Mean (SD) number of chronic conditions was 6.0 (2.4). Mean (SD) time from first observed PD diagnosis to the index treatment was 124.5 (153.2) days. Most commonly used index carbidopa/levodopa formulation was the 25/100-mg tablet (81.7%). Median index treatment duration was 238 days; 76.5% of patients discontinued index treatment (ie, had a gap in index treatment of ≥30 days) by follow-up end. During the follow-up period, 31.4% (n=5187) of patients used concomitant PD medication (median 90 days until start), with dopamine agonists being most common (19.7%). Among 5187 patients, 23.9% switched to/added a second class of concomitant medication (median 133 days until event), with dopamine agonist add-on combinations (with monoamine oxidase type B inhibitors or amantadine) being most frequent (49.6%).