December 8, 2015
Science Daily/The Lancet
Two studies conducted 20 years apart in England reveal an apparent increase in healthy aging, or years lived healthily, reflecting less cognitive impairment; and an increase in the proportion of life lived healthily, through a larger proportion of years lived with disability but less rather than more severe disability.
Whether rises in life expectancy result in increases in good quality years of life is of profound importance worldwide, with population ageing occurring in many countries. Jagger and colleagues investigated how expectancies in various domains of health have changed in England between 1991 and 2011, with identical study design and methods in each decade.
The research used baseline data from the Cognitive Function and Ageing Studies (study I in 1991 and II in 2011) which were led by the University of Cambridge, and which interviewed people aged 65 years or older in three geographically defined centres in England (Cambridgeshire, Newcastle, and Nottingham). Prevalence estimates for three health measures: self-perceived health (defined as excellent-good, fair, or poor); cognitive impairment (defined as moderate-severe, mild, or none, as assessed by Mini-Mental State Examination score); and disability in activities of daily living (defined as none, mild, or moderate-severe) were combined with mortality data to produce health expectancies for the three regions together.
Between 1991 and 2011, gains in life expectancy at age 65 years (4·5 years for men and 3·6 years for women) were accompanied by equivalent gains in years free of any cognitive impairment (4·2 years for men and 4·4 years for women) and decreased numbers of years with mild or moderate-severe cognitive impairment. Gains were also identified in years in excellent or good self-perceived health (3·8 years for men and 3·1 years for women).
Gains in disability-free years were much smaller than gains in excellent-good self-perceived health or in years free from cognitive impairment, especially for women (0·5 years compared with 2·6 years for men), mostly because of increased mild disability.
Further analysis showed that, despite a 20% lower prevalence of ill health in each age group in 2011, the overall prevalence in 2011 (9·7%) was higher than that in 1991 (9·3%), and, because of the increased numbers of people at the greatest risk, the absolute number of unhealthy individuals was larger.
The authors say: "During the past two decades in England, we report an absolute compression (meaning reduction) of cognitive impairment, an increase in the proportion of years of life spent in good health, and changes to the pattern of disability -- less severe disability is increasing but more severe disability is not. Reasons for these patterns are unknown but might include increasing obesity during previous decades. Our findings have wide-ranging implications for health services and for extension of working life."
They add: "Our findings of increases in the proportion of life spent healthily from age 65 years are in line with others across Europe. Evidence of expansion of mild disability has been reported in Spain and France, although some countries like Norway and the United States have experienced compression of disability."
Discussing the better medical management for various conditions such as heart disease and stroke over the past two decades, they say: "We need to quantify whether our findings are due to diseases and disorders becoming less disabling during the past two decades."
In a linked Comment, Dr Kenneth Rockwood, Dalhousie University, Halifax, NS, Canada, and Institute of Brain, Behaviour and Mental Health, University of Manchester, UK, says: "Even if the "problems of old age come as a package," quantification of the package in which those problems come is a challenge for ageing research...Policy makers must consider how health expectancy as, for example, disability prevalence, plays out against a background of an increasing number of older adults."