Overall health predicts mortality better than age

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Age plays almost no role in accounting for differences in older people’s health and well-being, according to a large-scale study by a multidisciplinary team of researchers at the University of Chicago.

Using what they call a “comprehensive model” of health and ageing, the team has shown how other factors such as psychological well-being, sensory function, mobility and health behaviors are essential parts of an overall health profile that better predicts mortality.

The research presents a sharp departure from the traditional biomedical model’s reliance on a checklist of infirmities centered on heart disease, cancer, diabetes, high blood pressure and cholesterol levels.

“The new comprehensive model of health identifies constellations of health completely hidden by the medical model and reclassifies about half of the people seen as healthy as having significant vulnerabilities that affect the chances that they may die or become incapacitated within five years,” said Professor Martha McClintock, a biopsychologist and lead author of the study. “At the same time, some people with chronic disease are revealed as having many strengths that lead to their reclassification as quite healthy, with low risks of death and incapacity,” added Professor Linda Waite, a demographer and study co-author.

The study, part of the US National Social Life, Health, and Aging Project, supported by the National Institute on Aging of the US National Institutes of Health, is a major longitudinal survey of a representative sample of 3,000 people aged 57 to 85 done by the independent research organisation NORC at the University of Chicago.

The study, the first of its kind to collect this sort of information from a scientifically selected group of people, yielded comprehensive new data about the experience of aging in America. In addition to finding that age plays little or no role in determining differences in health, the research found that: cancer itself is not related to other conditions that undermine health; poor mental health, which afflicts one in eight older adults, undermines health in ways not previously recognised; obesity seems to pose little risk to older adults with excellent physical and mental health; sensory function and social participation play critical roles in sustaining or undermining health; breaking a bone after age 45 is a major marker for future health issues; older men and women have different patterns of health and well-being during ageing; and mobility is one of the best markers of well-being.

McClintock is the David Lee Shillinglaw distinguished service professor in psychology. Waite is the Lucy Flower professor in sociology. Other members of the team are geriatrician William Dale, associate professor of medicine, and chief, section of geriatrics & palliative Medicine at UChicago Medicine; and sociologist Edward Laumann, the George Herbert Mead distinguished service professor in sociology.

The comprehensive model reflects a definition of health long advanced, but little studied, by the World Health Organisation, which considers health to include psychological, social and physical factors in addition to the diseases that are the basis for the current medical model of health.

The comprehensive model’s healthiest category represented 22% of older Americans. This group was typified by higher obesity and blood pressure, but had fewer organ system diseases, better mobility, sensory function and psychological health. They had the lowest prevalence of dying or becoming incapacitated (6%) five years into the study.

A second category had normal weight, low prevalence of cardiovascular disease and diabetes, but had one minor disease such as thyroid disease, peptic ulcers or anaemia and were twice as likely to have died or become incapacitated within five years.

Two emerging vulnerable classes of health traits, completely overlooked by the medical model, included 28% of the older population. One group included people who had broken a bone after age 45. A second new class had mental health problems, in addition to poor sleep patterns, engaged in heavy drinking, had a poor sense of smell and walked slowly, all of which correlate with depression.

The most vulnerable older people were in two classes – one characterised by immobility and uncontrolled diabetes and hypertension. A majority of people in each of these categories were women, who tend to outlive men.

“From a health system perspective, a shift of attention is needed from disease-focused management, such as medications for hypertension or high cholesterol, to overall well-being across many areas,” said Dale.

“Instead of policies focused on reducing obesity as a much lamented health condition, greater support for reducing loneliness among isolated older adults or restoring sensory functions would be more effective in enhancing health and well-being in the older population,” said Laumann.

The World Health Organization (WHO) defines health as a “state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.” Despite general acceptance of this comprehensive definition, there has been little rigorous scientific attempt to use it to measure and assess population health. Instead, the dominant model of health is a disease-centered Medical Model (MM), which actively ignores many relevant domains. In contrast to the MM, we approach this issue through a Comprehensive Model (CM) of health consistent with the WHO definition, giving statistically equal consideration to multiple health domains, including medical, physical, psychological, functional, and sensory measures. We apply a data-driven latent class analysis (LCA) to model 54 specific health variables from the National Social Life, Health, and Aging Project (NSHAP), a nationally representative sample of US community-dwelling older adults. We first apply the LCA to the MM, identifying five health classes differentiated primarily by having diabetes and hypertension. The CM identifies a broader range of six health classes, including two “emergent” classes completely obscured by the MM. We find that specific medical diagnoses (cancer and hypertension) and health behaviors (smoking) are far less important than mental health (loneliness), sensory function (hearing), mobility, and bone fractures in defining vulnerable health classes. Although the MM places two-thirds of the US population into “robust health” classes, the CM reveals that one-half belong to less healthy classes, independently associated with higher mortality. This reconceptualization has important implications for medical care delivery, preventive health practices, and resource allocation.

University of Chicago material
Proceedings of the National Academy of Sciences abstract

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