Factors Influencing Participation in Alzheimer’s Disease Clinical Trials

The rate of diagnosis for Alzheimer’s disease (AD) has continued to grow, and AD has a significant impact on the economy, costing billions of dollars each year and estimated to increase to $2 trillion by 2030. A study found that in 2020, 31,314 patients are needed to fulfill all AD and mild cognitive impairment (MCI) clinical trials in development.

“How many patient visits are needed to fulfill that number of subjects in these clinical trials? How many patients do we have to see at our private practice in order to fulfill that number?” asked presenter Domonique Nathan, MS. She discussed clinical trial enrollment in the past 10 years and presented the findings at the 13th Clinical Trials on Alzheimer’s Disease Congress 2020.

Researchers used theclinical research patient population at Abington Neurological Associates and reviewed patient medical records between Jan. 2010 and June 2020. They started with a subject pool of nearly 5,000 patients who were seen for AD or MCI. Of these patients, 434 qualified for a trial screening. Comorbidities eliminated most patients, said Ms. Nathan; other reasons included age (usually 85 years and older), lack of caregiver and/or spousal illness, and being deemed cognitively normal. Very few patients were disinterested in the clinical trials.

Among those, 338 were screened and signed informed consent. Reasons for declining participation included family/personal decisions (23%), lost to follow-up (18%), and being deemed unsuitable for trial (15%). A total of 181 patients who were screened went on to participate in a trial and receive a first treatment dose. After the screening, among patients who required amyloid evaluation, 117 went on to engage in a clinical trial.

Researchers advised that a review of a patient’s medical history and current medications should always occur prior to scheduling a screening visit. Certain preexisting medical conditions such as cardiac issues, substance abuse, and psychiatric concerns are often listed as exclusionary criteria for clinical trials. Additionally, patients who are taking prohibited medications or those who are not on stable medications at the time of screening can be excluded.

Once past the point of enrollment, patients may still be excluded from the trial based on adjustment of certain chronic medications, adverse events, or the inability of the caregiver to participate in the cognitive assessment of the patient, which is always mandatory for MCI and AD trials. The researchers also noted that is not uncommon for clinical trials to be discontinued due to a lack of efficacy or enrollment.

“Only 3.7% of all the patients we saw in the beginning qualified for the trial, enrolled, and received the medication,” said Ms. Nathan. Based on these data, in every 27 patients seen, only one qualifies to be randomized into a trial, she said. To answer the question from the beginning, Ms. Nathan said, “we would need to see 853,609 patients with memory and thinking complaints have to be seen in order to fill the clinical trial number.”

“The process of recruiting and enrollment is an extensive process, but it is necessary and quintessential to enrolling patients in these clinical trials,” she concluded.

Presentation: OC26: The Methodology and Probability of Recruitment and Enrollment into Phase 2 and 3 Alzheimer’s Disease and Mild Cognitive Impairment Clinical Research Trials. Presented at the 13th Clinical Trials on Alzheimer’s Disease Congress 2020, Nov. 4-7, 2020.