Ideally, the care of older persons should be grounded in the best available evidence about the benefits and harms of treatments. Unfortunately, high-quality evidence rarely exists. Good studies of a clinical condition often exclude older persons. Even when older persons are included, enrollment tends to be limited to healthy robust older persons who may little resemble the patient in front of you.
As a result, one can rarely practice true evidence-based medicine in older persons. Instead, one needs to examine available evidence and then critically assess the extent to which the evidence might apply to the patient being treated. To best make optimal clinical decisions, clinicians need to understand the limitations of applying the clinical research literature to their older persons and thoughtfully apply existing evidence to the individual patient they are treating.
THE CHALLENGES WITH CURRENT EVIDENCE
Clinicians are generally trained to consider outcomes from clinical trials as the gold standard for how to apply evidence-based medicine to clinical care. Ideally, clinical trials would include any patient who is a logical candidate for the therapy being examined regardless of age. Unfortunately, most clinical trials exclude patients for whom the therapy has a greater risk of side effects or patients who are at risk for not completing the trial. Study subjects excluded from clinical research represent a large proportion of patients seen in geriatric practice and often end up being the target population for the therapies being studied.
Zulman and colleagues have described a framework that outlines the reasons older persons may be excluded from clinical trials. These reasons include explicit age exclusions, implicit age exclusions, and unintentional age exclusions.
Many studies have age-specific cutoffs in which all subjects above a defined age are excluded. Although these exclusions are common, they can almost never be justified. An example of age restriction can be seen in analysis of representation of older persons in phase III clinical trials (last step required for the process of US Food and Drug Administration approval). Of the top conditions that caused hospitalizations and/or disability-adjusted life-years in older adults from 1965 to 2015, 33% had arbitrary upper age limits, and 67% reported on subjects younger than those typically afflicted by these conditions. Most studies with explicit age exclusions present absolutely no rationale to justify the exclusion.
An explicit age exclusion is only justifiable if one clearly would not offer a therapy in clinical practice to persons older than a particular age. In actual practice, most therapies tested in younger patients are eventually offered to older persons. Furthermore, explicit age exclusions ignore the vast heterogeneity in health in older persons.
More often, the reasons for excluding older subjects are more subtle. Many studies without an age cutoff have exclusion criteria ...