Which patients with Parkinson's disease participate in clinical trials? One centre's experiences with a new cell...

There is currently little evidence regarding the selection of patients for clinical trials in Parkinson's Disease (PD), especially those involving experimental therapies delivered using invasive techniques.

Understanding which patients are recruited will increase awareness of issues regarding parity of access to clinical trials and have an impact on the wider applicability of results, as well as provoking discussion regarding future improvements in the enrolment process.

TRANSEURO is an open label multi-centre surgical transplant trial which seeks to investigate the feasibility and efficacy of grafts of human foetal ventral mesencephalic tissue in patients with PD. The Cambridge based cohort of TRANSEURO participants (n = 26) was compared with a population representative sample of patients with PD eligible for, but not enrolled in, TRANSEURO (n = 33). Measurements were available in both populations for demographics, neuropsychological tests, tests of motor and non-motor function and quality of life.

Patients enrolled in TRANSEURO were younger and had significantly more years of education with higher scores on the revised Addenbrooke's Cognitive Examination. This difference was accounted for by memory, fluency and visuospatial subscores. There were significant differences in the Movement Disorder Society Unified PD Rating Scale scores with better motor function but more motor complications in the enrolled group. Those enrolled were also more likely to be under the care of the principal investigator of the study.

In this trial our population was younger and more educated with higher cognitive scores and better motor function than eligible PD patients not enrolled. This raises interesting questions about the parity of access to clinical trials of this nature amongst patients with PD.