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Help Industry With Clinical Trial Design

Participant Eligibility

When designing clinical trials, the Sponsor’s goal is to target the correct population so that the effectiveness and safety of the new therapy can be properly assessed. Your group can help the Sponsor understand factors that may need to be considered when defining participant eligibility by drawing on natural history studies, availability of diagnostic criteria, and the knowledge only people living with the disease may have.

  • Current diagnostic criteria: 
    • A clinical diagnosis is a diagnosis based on patient-reported and clinician-observed signs and symptoms. 
      • Usually this means there is not a specific test that can be performed to establish or confirm a diagnosis. 
      • Depending on the disease, this type of diagnosis can make it difficult to define a clear patient population to be involved in the clinical study.
      • Established consensus diagnostic guidelines can be invaluable for diseases with a clinical diagnosis, especially when multiple sites are going to be involved in the study.
      • A Center of Excellence Network can provide medical providers experienced in making the clinical diagnosis.
    • Even when there is a diagnostic test for the disease, participant eligibility may be limited if most clinicians forego the test due to cost or other barriers. But these barriers do not have to stop the clinical trial.
      • You may suggest the clinical study include the diagnostic test as part of the initial process for joining the study.  
      • If cost is the limiting factor, your group may be able to partner with a larger group or a philanthropic organization which can fund a program to offer diagnostic testing for free or at a reduced cost to those meeting clinical criteria.
      • If the diagnostic test is available at a limited number of medical centers, helping those with eligible clinical criteria arrange travel to 1 of these centers may be a feasible option.  
      • If, however, the diagnostic test poses unnecessary medical risk to patients, it may be most helpful to support the establishment of clear clinical diagnostic guidelines.
  • Comorbid medical conditions:
    • You can provide valuable information on comorbidities that researchers may not understand or expect. 
    • If subpopulations of the disease have very different comorbid diseases or conditions, study results may be very difficult to analyze. You may suggest the Sponsor considers:
      • Including only 1 subpopulation in the initial studies, preferably the subpopulation with no comorbidities or comorbidities least likely to affect the clinical outcome measures.
      • Clearly identifying the subpopulations at the beginning of the study and then separating the data by the different subpopulations during analysis.
  • Target symptom:
    • Many clinical trials are focused on a single symptom or a cluster of symptoms but the severity of the symptoms and even the presence of a specific symptom may vary across the patient population. 
    • The number and severity of disease symptoms may also affect a patient’s willingness to participate in a clinical trial, especially if the targeted symptom is not considered a high burden by the patient. 
  • Target stage of disease:
    • Sponsors may need to understand if the symptom(s) being targeted by their investigational therapy is only present or more likely to progress at specific stages of the disease.
    • Disease stage may affect a patient’s willingness to participate in a clinical trial, especially if the treatment is novel or poses significant risks.