Health in older adults has traditionally been defined as the absence of chronic “organ system” diseases, such as heart disease, cancer and diabetes.
But many experts have contended for decades that this “medical model” of health is incomplete, for it leaves out other factors that also affect an older individual’s health, such as psychological well-being, physical mobility and the ability to see and hear well enough to continue with daily activities.
Not only do these experts believe that the more “comprehensive model” of health and aging is a better indicator of health, they also claim that it is likely to be much more accurate at predicting a person’s risk of dying within the next five years.
A new, large-scale study, published this week by researchers at the University of Chicago, supports that view. It found that by relying on the old medical model, we’re getting a distorted view of who is healthy — and who is not.
“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 Martha McClintock, a University of Chicago biopsychologist and the study’s lead author, in a released statement.
“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 co-author Linda Waite, director of NORC, an independent research organization at UChicago.
The study was published Monday in the Proceedings of the National Academy of Sciences (PNAS).
Adding in new measurements
Data for the study was collected from a representative sample of 3,005 people aged 57 to 85 who were participating in the National Social Life, Health and Aging Project, a large, ongoing study of health and social factors that is funded by the National Institutes of Health. The data included not only medical information about the participants, but also information about their psychological and social well-being, as well as measurements of hearing, vision and mobility — “all key factors for independent living and a gratifying life,” write McClintock, Waite and their co-authors.
The researchers took that data and grouped the participants into distinct “constellations,” or classes, based on their health measures.
They hypothesized that including the measures of the five additional dimensions of the comprehensive model of health — health behaviors, psychological health, sensory abilities, chronic inflammation and mobility — “would illuminate the significant associations between functioning, wellbeing and disease in older people.”
Doing so, they added, would also “create a richer picture of the diverse types of aging and could inform the ongoing restructuring of the US health care system.”
Their analysis revealed the following key findings:
- Chronological age by itself plays little role in the differences in health status among older adults.
- Although cancer caused 24 percent of the deaths among the study’s participants over the age of 55, the disease by itself is not related to other medical conditions. Nor is it related to health behaviors, psychological health, sensory function and frailty. “Cancer seems to appear essentially at random in the general population of older adults; those who get it either succumb to the disease or are treated and recover, in which case, they are randomly distributed across classes like anyone else,” write the researchers.
- Obesity seems to pose very little risk in people with “excellent mental health, no chronic disease, intact sensory function, good health habits, and excellent physical functioning,” say the researchers. That is not true, however, for obese people with diabetes, poor mental health, poor sensory function and poor mobility. For them, obesity is “a very bad sign in a tidal wave of bad signs,” the researchers write.
- People who break a bone after age 45 — a group that includes about 1 in 7 older adults — make up an at-risk class that is “hidden” in the medical model of health. In the comprehensive model of health a broken bone is a significant “marker” for future health problems. “This group is an excellent ‘target’ for interventions — to prevent these individuals from declining over time and move them into more robust health,” the researchers stress.
- Another group hidden in the medical model of health are people with poor mental health — the 1 in 8 older adults who have high levels of stress, symptoms of anxiety and depression, loneliness, unhappiness and poor self esteem. “More of the people in this group sleep poorly, wake up tired, or drink excessively compared with those in the other group,” write the researchers. Also, their risk of becoming physically incapacitated or dying within five years is twice as high as people who are in good mental health.
- Not surprisingly, the most vulnerable group of older adults are those with serious problems in all health dimensions — chronic disease, cognitive impairment, poor mental health, poor sensory function, poor health behaviors and frailty. Forty-four percent of the people in this group (which comprises 1 in 8 older adults living at home) will die or become incapacitated within the next five years, the researchers report. That’s 9 percent more than identified by the traditional medical model of health, they add. “Clearly, the [comprehensive model] contains a great deal of prognostic information left out of the [medical model],” McClintock, Waite and their colleagues conclude.
It’s important to remember, of course, that the risks determined by this study are relative, not absolute. In other words, they apply to populations of people, not to individuals. Not everybody who breaks a bone after age 45, for example, is going to see their health deteriorate over the ensuing five years.
Nor do the findings of this study mean that factors such as diabetes, heart disease, obesity and smoking are not important.
What the findings do suggest is that we need a broader definition of health than that offered by the traditional medical model.
“We’re a mosaic of all of these traits,” McClintock told Reuters reporter Andrew Seaman. “In order to see the picture of health, you need to look at them together.”
FMI: The study can be read in full on the PNAS website.