Objective: To assess the long-term effectiveness of levodopa in Parkinson’s disease (PD) patients.

Background: To date, levodopa continues to be the most efficacious drug in controlling the motor symptoms of PD. There continues to be a controversy as to whether the effectiveness of levodopa decreases over time; however, there has been a lack of studies evaluating the long-term response to levodopa.

Methods: PD patients undergoing a levodopa challenge for deep brain stimulation (DBS) surgery evaluation from June 1997 through March 2017 were included. Only those patients taking levodopa and who had not had previous brain surgery were considered for inclusion. All individuals signed an IRB-approved informed consent for their data to be used for research. The patients were broken into four groups based on the disease duration (Group I: 0-5 years, Group II: 6-10 years, Group III: 11-15 years, and Group IV: > 16 years). Levodopa response was calculated based on changes in the UPDRS motor and activities of daily living (ADL) scores in the medication ON and OFF state.

Results: A total of 361 patients with PD were included. The mean age in Group I was 59.4 years with a mean disease duration of 3.9 years (n=29), Group II was 61 years with disease duration of 8.1 years (n=131), Group III was 64 years with disease duration of 12.8 years (n= 143), and IV was 66.5 years with disease duration of 18.5 years (n=58). There was a significant improvement in the UPDRS motor and ADL scores after the levodopa challenge for all groups. In Group I UPDRS motor scores improved by 32%, Group II by 45%, Group III by 46%, and Group IV by 44%. UPDRS ADL percentage improvement from the OFF to ON state were 23% for Group I, 50% Group II, 49% for Group III, and 45% for Group IV. The levodopa equivalent daily dose (LEDD) was 811, 1117, 1086, and 1079 for Groups I, II, III, and IV respectively.

Conclusions: In a group of PD patients undergoing evaluation for DBS, there was a marked improvement after an acute levodopa challenge. The improvement in motor and ADL scores did not decrease with disease progression suggesting that PD patients receive significant benefit with levodopa throughout the disease course. Therefore, levodopa treatment should not be withheld due to concerns of long-term loss of efficacy.

References: 1. López, I. C., Ruiz, P. J., Pozo, S. V., & Bernardos, V. S. (2010). Motor complications in Parkinsons disease: Ten year follow-up study. Movement Disorders, 25(16), 2735-2739. 2. Fabbri M, Coelho M, Abreu D, et al. Do patients with late-stage Parkinson’s disease still respond to levodopa? Parkinsonism Relat Disord. 2016 May;26:10-16.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/long-term-response-to-l-dopa-in-parkinson-disease/