Objective: To compare demographic, clinical, and socioeconomic characteristics of patients with Parkinson’s Disease (PD) who declared interest in participating in clinical trials with those who did not.

Background: Clinical research relies on the successful recruitment of representative patient populations. The validity and generalizability of trial findings may be affected if patients with more advanced disease or specific socio-demographic characteristics are underrepresented. Understanding factors associated with willingness to participate in clinical trials is essential to improve future trial design and recruitment strategies.

Method: We analysed cross-sectional data from a longitudinal nationwide PD registry in Austria. An expert-confirmed diagnosis of PD was the key inclusion criterion and standardized questionnaires and clinical rating scales were used. Participants were divided into two groups according to their self-reported interest in clinical trial participation. Group differences were assessed using parametric and non-parametric statistical tests depending on variable type and data distribution.

Results: 395 (72.7%) of 543 PD patients expressed an interest in clinical trial participation. Patients interested in participation were significantly younger (67.7 ±10.2 vs. 72.8 ±9.1 years, p<0.001), had a shorter disease duration (9.2 ±6.8 vs. 11.7 ±8.6 years, p=0.003), lower Hoehn and Yahr stages (median 2.0 vs. 3.0, p<0.001), and MDS-UPDRS (sub-)scores (total score and parts I–III, all p<0.001) in ON-stage. They were less likely to be functionally dependent (36.2% vs. 58.5%, p<0.001), to receive care allowance (24.8% vs. 41.9%, p<0.001), or to reside outside their own home (2.8% vs. 10.1%, p=0.003). Postural instability, gait disorder, dysphagia, dysarthria, freezing of gait, cognitive impairment / dementia, depression, sexual dysfunction, urinary problems, and constipation were significantly less common in patients interested in trial participation (all p<0.026). Sex and the presence of motor fluctuations did not differ between groups (all p>0.360).

Conclusion: PD patients with more advanced disease and higher levels of disability appear underrepresented among those willing to participate in clinical trials, highlighting a potential recruitment bias that should be considered in the design and interpretation of clinical trials.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/interest-in-clinical-trial-participation-in-parkinsons-disease-insights-from-a-nationwide-registry/