What is Health?
By: David Neal
Tags: Systems Thinking, Healthcare, Health, Health Care Reform

If you haven’t got your health, what have you got? But then again, if you have got your health, what have you got?

‘Health’ in some sense of the word, is a major personal, professional and macro-economic force in the world. And now more than ever, health is at the eye of a whirlwind of technological and social change.

But so much activity risks hiding the wood for the trees. What does it mean to be healthy? What is ‘healthcare’ and what should it achieve? What is ‘digital health’?

We can’t understand any concept that adds a prefix or suffix to health unless we understand what health is. And if we don’t understand what these things mean, then what are we all running around spending so much energy doing?

Aristotle was amongst early thinkers to note a problematic ambiguity of the term ‘healthy’:

‘Everything that is called healthy is so called with reference to health — some things by preserving it, some by producing it, some by being signs of health, some because they are receptive of it’.

But none of those define health, the thing itself.

2300 years of human endeavour later, in 1946, the World Health Organization, who, let’s face it, ought to be the experts, came up with a much-quoted definition that made health: ‘A state of complete mental, physical and social well-being, and not merely the absence of disease or infirmity’.

But that seems to be a tremendous fudge. The casual use of ‘well-being’ to define ‘health’ should immediately prompt a challenge — try defining ‘physical well-being’ without using the words, ‘health’, ‘healthy’ or ‘well’.

You might also be wondering, if that’s what it takes to be healthy, has any person in all of human history ever actually been healthy? Maybe, maybe not. It’s certainly aspirational.

Perhaps health isn’t a thing, or a state. Could it be a process? This was the idea behind the wellness model of health developed through WHO from 1984. The 1986 Ottawa Charter for Health Promotion suggested that health is:

“The extent to which an individual or group is able to realize aspirations and satisfy needs, and to change or cope with the environment. Health is a resource for everyday life, not the objective of living; it is a positive concept, emphasizing social and personal resources, as well as physical capacities.” (Health promotion: a discussion document. Copenhagen, WHO, 1984.)

A similar and very broad definition re-emerged in the late 1990s:

“The capability of individuals, families, groups and communities to cope successfully in the face of significant adversity or risk.” (Vingilis & Sarkella, Social Indicators Research 1997;40:159)

Whilst these definitions do well in moving away from an artificial binary distinction between a ‘healthy state’ vs ‘unhealthy state’ and address the issues of tautology and un-attainability, they are reasonably (read very) imprecise.

If not a state and not purely a process, can a hybrid model of health be found. What if health is an emergent property of a system of interactions between an individual and the environment? An emergent property can be present at a given point in time, depending on the functioning of the system but in a dynamic system, there will also be a state of constant flux. Continuous change with a particular velocity — a pace and direction — at any given moment is also a function of the interactions in the system.

What is the system in which a human being finds itself? We have an ‘internal’ system and we exist as part of an ‘external system’.

The internal system is built up from atoms, ions and complex molecules (DNA, proteins, fatty acids), which collectively organise into organelles, which organise into cells, which organise into tissues, which organise into organs, which organise into organ systems, which organise into the anatomical individual. Electrostatic forces, diffusion and osmotic gradients, covalent bonds forming and breaking, electrical potentials, pressure gradients, neuronal action potentials and muscle contractions keep the internal system in constant motion at every level from the subatomic to the physiological, and, unless you believe in a divine spirit, the psychological.

The anatomical individual is one organism surrounded by other organisms of the same species (they are a member of a family, within a community, within in a global population of billions) and other species (from bacteria to blue whales) and a wide variety of inanimate substances — all the minerals, gases and liquids. The individual is bombarded with radiation, subject to conduction and convection forces and is subject to collisions with other organisms and substances.

Some of the interactions between the environment and the individual trigger specific sets of changes in the internal system. Light on the retina triggers action potentials in neurons of the optic nerve resulting in a pattern of neuronal activation called sight. Kicking a rock physically disrupts a large number of cells, triggering a predictable series of chemical reactions that result in the phonation ‘ouch’.

To maintain such a complex and highly organised system, the organism must also interact with matter from it’s environment in such a way as to incorporate that matter into its own anatomical components (to grow and sustain its structure) and in such a way as to perpetuate the exothermic reactions that release the energy required to maintain specific electrical potentials, pH balances and other solute concentrations.

Humans have developed very complex nervous systems — networks of highly specialised cells called neurons, which generate electrical currents in response to changes in the environment, or in response to electrical stimulation by other neurons. It is the latter kind of interaction — between neurons and other neurons — which is more complex in humans than in most other species and is widely believed to result in a lot of our most peculiarly human capacities: language, imagination, empathy, the ability to inhibit immediate impulses in the pursuit of long-term rewards.

Because of these abilities we are able to set goals and we are able to form expectations about our own status and function, about the world around us and about how we interact with the world. We learn these abilities through experience from continuous second by second interactions between the physical and social world around us and our own physical and psychological being.

So a human being as a complex biological system has a moment-by-moment state, representing its capacity to perceive and interact with the world around it, and a velocity of change of the state of the system.

Taking the Ottawa Charter definition a step further, then, as a human being in my surroundings, I would be in a state of health by fulfilling two propositions:

In the light of the mental, physical and social challenges the world is presenting me with, I am currently able to function (mentally, physically and socially) to the level at which I expect to do so, in the pursuit of my goals; and The combined contextual factors of my life — my habits, behaviours, diet, physical environment, social, economic and cultural environments — are such that my risk of being unable in the future to function to the level at which I expect to do so, in the pursuit of my goals, is not demonstrably significantly greater than that of my peers.

This framing of health has several important implications:

‘Health’ is subjective as it relates to my expectations and my goals. Thus, someone who has been blind from birth may be considered a ‘healthy’ adult if they have built a life in which their physical impairment does not violate their expectations or prevent them from reaching their goals, whilst a newly blind adult having lived a fully-sighted life may be unhealthy because the same impairment prevents them from achieving goals that they had set themselves, and fully expected to achieve, whilst sighted.

Life is challenge and health describes an ability to meet those challenges. This capacity if clearly not only finite but paradoxically non-existent, since we all suffer losses, most notably the inevitable and greatest loss that is death. We are all ultimately unable to meet the challenges we face. However, in the short term, on a situation-by-situation basis, we do overcome innumerable challenges just going about our daily lives — earning money or interacting with our environment to feed, clothe and protect ourselves can present great challenge.

Health is a dynamic state and in addition to a snapshot of our state, a comprehensive definition describes a velocity — a direction and speed at which we are moving through the world, towards being more able or less able to function in the face of challenge in the future. That velocity is determined by every minute interaction with the environment on an ongoing basis, with some interaction nudging us towards impairment and ill health, some interactions nudging us towards improved function and good health. My current health consists of my current level of function and the net value — positive or negative — of my interactions with my environment with respect to health.

The above point describes risk and risk management. It would be unhelpful to base a definition of health on the absolute risk of adverse events, since in the long run the probability of the worst possible outcome, death, is 1 (100%). “Life is a universally fatal sexually-transmitted disease.” (P. Skrabanek & J McCormick: Follies and fallacies in medicine. Tarragon Press, 1992). A risk relative to a reference frame is needed. For the reference frame, a group of peers — a ‘population’ in statistical terms — might be useful.

Many quantifiable risk factors for future ill health — weight, blood pressure, etc. — are normally distributed in the population. That is, there’s a spectrum of values, symmetrically distributed ‘more or less’ around a middle (mean, or average) value. Large scale studies can identify risk factors that actually split that population into groups which seem to have slightly higher or slightly lower risks of future ill health. The larger the study, the smaller a difference in risk that a study might be able to identify. A risk that is ‘significantly’ different from one’s peers could have several definitions statistically: it could be defined as being a certain number of standard deviations from the mean for a normally distributed measure like blood pressure. Or it could be that a study comparing groups with and without a risk factor present identified a ‘statistically significant’ increased risk of an outcome (which says nothing of the size of the increased risk, but merely describes a degree of certainty with which we can say there is any real difference). Equally, ‘significant’ could be a subjective quality, describing the amount of attention given to the nature and scale of a risk by an observer, or the strength of the risk as a behavioural modifier for that person to change their risk exposure.

Evidently, if we cannot perceive and demonstrate a risk, it cannot be usefully taken into account when attempting to describe our health trajectory. For example, before asbestos was discovered to be associated with lung fibrosis and mesothelioma, those people exposed to it were undoubtedly at risk but could not have done anything about it because no one knew that there was a risk. However, demonstrably in this context goes further and describes our ability to communicate a ‘known’ risk from academic observation and research to the people experiencing those risks. If I performed some research that identified a group of people at much higher risk of death from eating a particular food but none of those people, nor anyone else in society, knew that eating that food could cause premature death, then the only conclusion that anyone else could draw would be that these were very healthy people who were inexplicably becoming ill and dying. Only if the knowledge of the risk is spread throughout society, can it become to describe a state of ill health to engage in that activity, or be in that environment.

As expectations increase, subjective perceived health would be expected to fall and utilisation of healthcare resources to rise. You can become less healthy by having higher expectations than current circumstances constrain your level of function to, without altering your physical state. Conversely, low expectations don’t make you any healthier than ‘realistic’ expectations (that is to say, expectations at the upper limits of what the constraints of circumstance permit) of one’s ability to function, now and in the future.

There are some tricky questions that this definition raises. What would be a valid measure to evaluate health status or ‘healthiness’ of a person? What would be valid measures of the effectiveness of things designed to support or improve health? How should we be doing ‘healthcare’ or ‘digital health’ or ‘medicine’?

I’ll start to address these questions in the next blog.