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The UN World Population Prospects 2019 initiative estimated that people older than 65 years will represent 25% of the population in North America and Europe by 2050. Although the elderly population continues to grow and is estimated to carry nearly 60% of the chronic disease burden in the U.S., only about one-third of participants in phase II and III clinical trials are older than 65 years. Furthermore, older adults are significantly underrepresented even in clinical research on diseases that predominantly impact elderly people, including arthritis, incontinence, Alzheimer’s disease, and cancer. Consequently, treatments and therapies assessed in clinical trials may not be generalizable, safe, or effective among older adults. Given that the elderly population is growing rapidly—and that this group is particularly vulnerable to morbidity and mortality from disease—there is an urgent need to increase elderly participation in clinical trials across diverse treatments, therapies, and drugs.   

To develop strategies for more inclusive recruitment, researchers first must understand the factors that contribute to elderly underrepresentation in clinical trials. Several studies report that age-related physiology is a primary contributor to low participation among older adults, especially in drug trials. Specifically, geriatric patients are more likely to experience multiple comorbidities and polypharmacy, which at best may confound study results and at worst may increase the likelihood of adverse treatment effects among older adult participants. Old age also is associated with changes in drug uptake, metabolism, and response that may complicate the evaluation of new drugs within age-diverse groups. As a result, less than two-thirds of initial approval documents for FDA-approved pharmaceuticals show information on pharmacokinetics in the elderly, and less than half provide information about safety and efficacy in this population.

Other contributing factors include social determinants of health, such as living accommodations, transportation options, and access to online resources. For example, an elderly person housed in an assisted living facility may have limited capacity to leave freely and may be unable to operate or access a personal vehicle, impeding their ability to travel to and from clinical research centers. Research finds that patients living less than seven miles from a recruitment center are significantly more likely to be elderly, suggesting that transportation and accessibility are major barriers to study participation among older adults. Elderly populations may also be less likely to learn about clinical trial opportunities through increasingly common online recruitment strategies, as only 73% of adults over than 65 years old reported using the internet in 2019, compared to more than 90% of U.S. adults overall.

To address these disparities, in March 2020 the FDA released draft guiding recommendations for inclusion of older adults in cancer clinical trials. Recommendations included using age-stratified trial designs, targeting recruitment efforts to older adults, reporting smaller age subgroups, and developing strategies to monitor and manage geriatric adverse advents. Other (non-FDA) recommendations have included creating more clinical trials dedicated specifically to older patients and minimizing stringent exclusion criteria related to comorbidities and polypharmacy. With hope, these dedicated efforts to include older adults in recruitment for clinical trials will reduce research underrepresentation of this vulnerable, rapidly growing population.

References:

1 United Nations (UN). World Population Prospects: 2019 Revisions. (2019). Accessed from: https://population.un.org/wpp/

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5 Ruiter R, Burggraaf J, & Rissmann R. (2019). Underrepresentation of elderly in clinical trials: An analysis of the initial approval documents in the Food and Drug Administration database. British Journal of Clinical Pharmacology, 85:838-844. 

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7 Pew Research Center. Internet/Broadband Fact Sheet. (2020). Washington, D.C.: Pew Research Center. Accessed from: https://www.pewresearch.org/internet/fact-sheet/internet-broadband/

8 Food and Drug Administration (FDA). Inclusion of Older Adults in Cancer Clinical Trials: Guidance for Industry. (2020). Accessed from: https://www.fda.gov/media/135804/download

9 Whelehan S, Lynch O, Treacy N, et al. (2018). Optimizing clinical trial design in older cancer patients. Geriatrics, 3(34).