Objective: To report our experience of recruiting Parkinson’s disease (PD) patients with mild-to-moderate anxiety into a randomized controlled trial.

Background: Anxiety is a common non-motor symptom in PD. There is a paucity of information on recruitment experience and strategies in clinical trials involving PD patients with anxiety.

Method: The Treating Anxiety in Parkinson’s Disease with a Multi-Strain Probiotic study (NCT03968133) is a 12-week, randomized, blinded, placebo-controlled trial aimed to assess the effect of a multi-strain probiotic in PD patients with mild-to-moderate anxiety. Patients were primarily recruited from a large tertiary movement disorders clinic in British Columbia, Canada, between December 2020 and February 2023. Additional recruitment efforts were performed through other regional movement disorders clinics, general neurology clinics, PD organizations, and online. Anxiety levels were assessed using the Parkinson Anxiety Scale, the Mini International Neuropsychiatric Interview, and the MDS-Unified Parkinson’s Disease Rating Scale item 1.4 (anxious mood).

Results: Out of 1013 patients pre-screened for the trial, 845 were referred by site personnel, 120 were identified through other PD studies at the clinic, 47 were self-referred, and 1 was referred by a specialist. Of these, 468 patients were determined to be ineligible. Out of 545 potentially eligible patients, we successfully established contact with 490 patients and 311 agreed to receive the consent form for review. A total of 143 patients provided written informed consent and were screened for eligibility. Of those recruited and screened, 56 participants (39.2%) did not meet the inclusion criteria for anxiety, 7 (4.9%) did not meet other eligibility criteria, 13 (9.1%) declined to complete all screening procedures, and 6 (4.2%) were lost to follow-up. We reached and exceeded our enrollment goal of 60 participants after 25 months of recruitment, with 61 participants randomized to receive probiotics or placebo.

Conclusion: The percentage of patients recruited was small (14.1% of all pre-screened). Despite the high prevalence of anxiety in PD, many of those recruited did not meet the criteria for anxiety. This study highlights the challenges of recruiting this specific group of PD patients into clinical trials and has implications for future trial design.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/recruitment-of-parkinsons-disease-patients-with-mild-to-moderate-anxiety-into-a-randomized-controlled-trial-experience-of-a-large-canadian-tertiary-movement-disorders-clinic/