Health perspectives: international epidemiology of ageing.

Populations globally are ageing, in part due to dramatic increases in life expectancies, forcing a reconsideration of what constitutes being "elderly" and "old." The proportion of older adults living with disability may be decreasing, yet older individuals are living with a significant burden of chronic disease, geriatric impairments in cognition, vision and hearing and reduced physiological reserve (frailty). Caring for a growing number of medically complex individuals has implications for medical workforce size and composition, health programmes and expenditure. Future responses to an ageing population will require further innovation in health-care delivery models, and increasing representation of older adults in clinical trials. 2011 Elsevier Ltd. All rights reserved.