Objective: To report on a survey of Parkinson’s disease (PD) experts on the inclusion of PD patients with deep brain stimulation (DBS) in clinical trials.

Background: DBS patients are often excluded from enrollment in PD clinical trials in spite of increasing prevalence of DBS implantation and acceptance of DBS as a standard in the continuum of PD care.

Method: A web-based survey, sent to all Parkinson Study Group (PSG) members, contained questions about participants’ roles in PD clinical trials, PSG investigator status, whether DBS patients should be excluded from different types of PD clinical trials, time after implantation and duration of stable DBS settings prior to enrollment, and whether DBS settings should be treated similarly to medications in terms of stability during the trial period. Individual responses were extracted to a database for analysis.

Results: 11/115 responses were excluded (not involved in design or execution of PD trials). Of 104 analyzed responses (n=61 physicians, n=29 coordinators, 14=other), 72.1% were involved in PD DBS clinical care. Only eight (7.7%) respondents thought that DBS patients should be categorically excluded from PD clinical trials. Responses from the remaining 96 respondents cited factors such as ethical concerns regarding excluding DBS patients (principles of justice and beneficence), the increasing proportion of DBS patients, the need for study-drug mechanism considerations, outcomes and safety in relation to DBS, and the need for carefully powered and randomized studies to appropriately include DBS patients. The greatest support (>85%) was for inclusion of PD DBS patients in observational, exercise, and non-motor symptoms studies, followed by motor (76%), disease-modifying (69%), other device (58%) and gene therapy/stem cell (55%) studies.  Over 70% of participants favored enrollment six months or one year after implantation (target dependent), and within three or six months of stable settings. 74% agreed that DBS settings could be considered similar to dopaminergic therapy in terms of adjustments.

Conclusion: A large majority of surveyed PD trial experts with experience in DBS care agree that PD DBS patients should not be categorically excluded from clinical trials but study-specific features are important to consider. Enrollment concerns can be mitigated by using appropriate methodology and statistical design.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/re-thinking-enrollment-of-deep-brain-stimulation-patients-in-parkinsons-disease-clinical-trials/