(p. 189) Limitations in the evidence for safe and effective medications for older people 

In the last decades, evidence-based medicine has emerged as the approach to promote the best clinical practice for health problems. It collates the best published evidence, preferentially based on randomized clinical trials, to guide clinical practice. However, the growing older population challenges the evidence underpinning ‘best practice’. Many older patients are characterized by multimorbidity and polypharmacotherapy, present various degrees of functional and cognitive impairment, and are at risk of developing geriatric syndromes. For these reasons they have been almost systematically excluded from clinical trials. In addition, the results of clinical trials are difficult to apply to patients with these characteristics, given the high risk of drug–drug and drug–disease interactions. An effort to promote a greater involvement of older patients in clinical research is needed, using specific measures to facilitate the participation of complex older patients, who are representative of those treated in clinical practice.