Abstract
A major challenge facing society is how we can maintain health and quality of life in an aging population. Maximum life expectancy has not changed substantially, but average life expectancy has increased greatly in the past century. This reflects profound improvements in mortality in infancy and young adulthood, resulting in a much greater proportion of people surviving to older ages (tables 1, 2, and 3). View this table: Percentage of people surviving to,and further expectation of life from, age 55 and age 75, by year of birth,1841−19811 View this table: Table 2 Estimated number (percentage) in the population aged 60 years over in UK2 View this table: Table 3 Expectation of life for people of various ages, according to death rates assumed for remainder of their lifetimes, United Kingdom2 The rise in numbers and proportion of older people has led to much concern about societal consequences, not least health consequences. Increasing age is associated with increasing disability and loss of independence, with functional impairments such as loss of mobility, sight, and hearing. In Britain in 1984-5, the estimated prevalence of those with severe disability was less than 1% in those aged 50-59 years but 13% in those aged over 80 years.3 Murray and Lopez have estimated that at age 60, we might expect to live about a quarter of our remaining years with some disability.4 5 If the average age of onset of ill health is unchanged, increased life span would mean more years of ill health before death for an individual and a greater proportion of people with disability. Much current discussion thus revolves around how best to support and care for large numbers of older people with disability. According to Fries, the age of onset of ill health might, however, rise more quickly than our life span increases, resulting in “compression of morbidity” …