Tuesday, February 1, 2011

How to Compress Your Morbidity

Let's talk about dieing. I don't mean death itself, which has all kinds of philosophical and religious issues attached to it, but rather the physical and mental processes leading up to death, which involve more factual, scientific issues.

All of us will die and nobody knows exactly when. Despite the uncertainty as to the timing of death, most of us have an idealized model of how we want to die: continued high level of physical and mental functioning for as long as possible and then rapid decline just before the end. This period of decline in which we are infirm, diseased, disabled and/or demented is called morbidity, and we wish it to be as short as possible, followed by a quick and painless death.

About 30 years ago a gerontologist by the name of J.F. Fries proposed what he called "the compression of morbidity hypothesis." According to Fries, there are natural limits on how long humans can live, and improvements in health care, life style, and reductions in the effect of environmental risks are steadily progressing us to a maximum life expectancy, which he believed at the time was about 85 years. He proposed that the same factors that produce a longer life would also produce a "compression" of morbidity because they would lead to a lower incidence of chronic disease and a higher age of onset of chronic disease.

The compression of morbidity hypothesis is certainly attractive because it fits our idealized model of dieing, and it would be great if it were correct. Unfortunately the gerontological research over the last 30 years seems to indicate that Fries was wrong on two counts. First, life expectancy in at least one country (Japan) has now exceeded Fries' proposed limit of 85, and is still increasing almost linearly in most countries (Christensen et. al, 2009), though there is perhaps some leveling off in the U.S. (Crimmins & Beltrán-Sánchez, 2010):

Large declines in mortality rates in recent decades have translated into sizable increases in survival at older ages. For example, in the United States, the probability of a 65-year-old surviving to age 85 doubled between 1970 and 2005, from about 20% in 1970 to about 40% in 2005 (Bell & Miller, 2005). Similar or greater increases in survival at older ages have been reported in most developed countries among people aged 80 years or older since the 1970s (Kannisto, 1994, 1997; Vaupel, 1997). As life expectancy has increased, the modal age at death has steadily increased so that death in low-mortality countries most frequently occurs to people in their late 80s and 90s (Robine, 2010). Even death rates among people above age 100 have declined significantly in recent years leading to an increasing number of centenarians (Kannisto, Lauritsen, Thatcher, & Vaupel, 1994; Robine, Saito, & Jagger, 2003; Vaupel, 2010). This steady rise of life expectancy even at the oldest ages indicates that humans are not yet pushing up against a fixed limit, one that cannot be exceeded, which is a central tenet underpinning the compression of morbidity hypothesis." (Crimmins & Beltrán-Sánchez, 2010)

Although this may seem like good news -- we're living longer -- the data also show incidence of disease and disability has increased, not decreased in elderly populations, contrary to the compression of morbidity hypothesis (Christensen et. al, 2009; Crimmins & Beltrán-Sánchez, 2010). With respect to physical mobility problems, for example, data from the National Health Survey compared the percent of people in different age groups in 1998 and 2006 who reported being unable to perform at least one of the following: walking 1/4 mile, walking up 10 steps, standing or sitting for 2 hr, and standing, bending, or kneeling without using special equipment. The results show no support for a compression of this kind of morbidity:

For a number of other sources of morbidity, like cardiovascular disease, stroke & heart attack, diabetes, & cancer, the research comparing 1998 and 2006 indicates "There is no hint of a declining prevalence of disease over these eight years....The most striking change over the ten-year period is the increase in all the CVD conditions among older males; for females, the increase among the oldest group only occurs in the prevalence of stroke. Older men and women show an increased prevalence of cancer. Diabetes increases are seen through much of the adult age range" (Crimmins & Beltrán-Sánchez, 2010). Since mortality rates in older age groups have been decreasing during the same period, this means the number of survivors of these diseases has generally increased, often with decreased functioning associated with the management of the disease.

Now that you're suitably depressed, let me point out that the studies reviewed above deal with population trends and don't negate the possibility of individual factors that might contribute to compression of morbidity. Indeed, there is data showing that life-style choices (diet, exercise, weight control, preventative health-care, etc.) may compress morbidity for specific individuals, though more studies along this line are needed to be more definitive. In one study, 418 people were followed over 12 years (1986-1998) in terms of how their lifestyles (smoking, exercise, weight) related to morbidity patterns. Those with healthier lifestyles showed either a slight increase in morbidity over time with no acceleration of disability before death, or only a brief period of accelerated morbidity before death (Hubert, et. al., 2002), consistent with the idea of morbidity compression. In short, it is certainly possible to have some degree of control over your own individual morbidity pattern.

Another more optimistic point is that even if we must live with disease or disability in our later years, there are more ameliorative resources available all the time. As Christensen et. al. (2009) have noted, the rising use of assistive technology and improvements in housing standards, public transport, accessibility of buildings, changes in social policies, shifting gender roles, and the social perception of disability may loosen the link between disease and functional limitation of disability. Of course, these things are somewhat dependent upon governmental policy and therefore the political climate. Given our current health care debates in the U.S. we may find ourselves well behind other developed countries in offering preventive and ameliorative resources.


Christensen, K., Doblhammer, G., Rau, R.Vaupel, J.W.(2009). Ageing populations: the challenges ahead. Lancet. 2009 October 3; 374(9696): 1196–1208

Crimmins, E.M., & Beltrán-Sánchez, H. (2010). Mortality and morbidity trends: is there compression of morbidity? Journal of Gerontology: Social Sciences, 66B(1), 75–86.

Fries, J. F. (1980). Aging, natural death, and the compression of morbidity. New England Journal of Medicine, 303, 1369–1370.

Hubert HB, Bloch DA, Oehlert JW, Fries JF. (2002) Lifestyle habits and compression of morbidity. J Gerontol A Biol Sci Med Sci. 2002 Jun;57(6):M347-51.

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