Elderly persons comprise a large, and the fastest-growing, portion of the population in the U.S. and other advanced nations. They are also make up the lion’s share of patients for certain health conditions, including cancer, cardiovascular disease, arthritis, and Parkinson’s disease, among others. The elderly also are the main users for many medications, especially those treating chronic conditions.
So it’s more than a little ironic that elderly patients are greatly underrepresented in clinical trials for remedies for those conditions. For example, three-quarters of U.S. patients who are diagnosed with lung cancer are at least 65 years old, but only a little more than a third of the patients in clinical trials for lung cancer were in that age group.
Similarly, in a widely-noted study from 2011, University of Michigan researchers analyzed 109 reports issued in 2007 on clinical trial projects. They found that fully one-fifth of those studies imposed age limits, most commonly 65, on trial participants despite no apparent medical justification (the practice was even more pronounced ten years earlier, when over one-third of trials did that).
Of the rest of the clinical trials in 2007, about half set non-age criteria for participants, such as rejecting those who were frail or mentally impaired, that were in practice far more likely to screen out older persons.
Many reasons have been advanced to explain under-representation of the elderly in clinical trials. Some point to medical factors, such as higher risks of adverse effects, lower life expectancy, and the greater likelihood older patients will have multiple ailments and take other medications.
Psychological and ethical challenges may also pose obstacles in obtaining informed consent, and elderly patients may also have greater difficulty in traveling to get treatment, or in getting support needed to follow treatment protocols.
Despite that, a consensus is building among researchers against many age restrictions in clinical trials. Twenty years ago, the International Conference on Harmonisation (ICH), an international initiative of U.S., European and Japanese health experts interested in setting good practice standards for clinical trials, noted it was impossible to predict from clinical trials that exclude elderly patients “all potential differences in pharmacokinetics, pharmacodynamics, disease-drug interactions, drug-drug interactions, and clinical response” that geriatric patients might experience.
The ICH called for including elderly in clinical trials for all therapies intended for adults. Its “Studies in Support of Special Populations: Geriatrics,” issued in 1994, urged clinical trial protocols to avoid arbitrary upper age limits.
It also recommended not excluding elderly from trials even if they have other ailments, since doing so prevents uncovering interactions of multiple drugs or diseases. In fact, the European Medicines Agency has refused to approve at least one drug for use for patients over age 80 because clinical trials for the drug had included very few patients in that age group.
In the U.S., Food and Drug Administration guidance advises researchers not to exclude trial participants solely on the basis of age, and also urges inclusion of “an appropriate representation” of elderly patients in clinical trials to gauge safety and effectiveness in older patients, and to allow comparisons with their impact on non-elderly patients.
Increasingly, medical researchers are recommending that clinical trial sponsors raise age limits for trial participants (say, from 65 to 75) or eliminate them entirely, and that any age limits in trial protocols be medically justified.
They also urge building into trial designs one or more subgroups of elderly patients, based on their other ailments and medications, to better study interactions. They also want contract research organizations to train investigators better in dealing with elderly patients’ special difficulties and to pay more attention to accommodating them.