Healthcare theory

What theory underlies the delivery of healthcare? The design of hospitals, services, policies, and almost every other aspect of healthcare in the UK occurs without reference to any theories. Yet, as Priscilla Alderson stressed in 1998, theories are crucial: “… theories are at the heart of practice, planning, and research. All thinking involves theories …” She emphasised that all planning involved theories, whether acknowledged or not, saying, “… when theories are implicit, their power to clarify or to confuse, and to reveal or obscure new insights, can work unnoticed.” In this post, I explore what implicit theory underlies healthcare, whether it is appropriate when considering rehabilitation services in contrast to acute services, and why a new theory is needed for rehabilitation.

If you think theories are an unnecessary luxury, consider how you approach a breakdown in your car, a problem with your computer and printer, or a discussion about the best way to set goals. In each case, you will use an implicit theory about how the car, computer, or setting of goals achieves its purpose. Your response would be better if you made your theory explicit in each case.

Table of Contents


Humans solve problems. Initially, this likely involved random trials ‘to see what happened’; we may still do the same if faced with a new situation. Early philosophers in Ancient Egypt, Greece, and Persia soon developed more systematic methods of investigation. These involved understanding the phenomenon and looking for similarities to problems already solved.

Over time, a more systematic approach developed, collecting sufficient data to determine the problem type for further analysis. One way to characterise type is to ask, what model is appropriate for this problem? For example, is it a logical puzzle, a linguistic problem, a mechanical problem, a behavioural problem, etc.?

Ill health is a common problem, and people with expertise in helping people with ill health emerged in most cultures; some were priests, others wise people, etc. Their common feature was to depend on an explanatory model when deciding what to do.

For example, if the explanatory model concerned offences against gods, some action to appease the gods would be recommended. Homeopathy is another example of an explanatory model, its key features being:

  • A substance that produces similar symptoms in healthy people will cure the problem.
  • The lower the dose of the treatment, the greater its effectiveness.

Using these principles, a treatment is recommended.

Considering current healthcare, I separate two components. Individuals will use their explanatory model to manage their illness; they have a personal healthcare theory. However, any socially supported system will use a commonly accepted model; this leads to the public healthcare theory. I am considering public explanatory models.

Emergence of a public healthcare model.

The primary public model of illness is the biomedical model, which I have described recently. I will recapitulate its evolution here.

Over most of history, people and societies have used many explanatory models to understand illness. One example is the model based on the balance of four humours, which Hippocrates may have developed from Empedocles’s theory about the elements of matter. It influenced healthcare for centuries. It differed significantly from most earlier models by attributing illness to a natural phenomenon rather than a mystical or spiritual cause. Another influential model is the Yin and Yang theory of balance, which is the basis for Traditional Chinese Medicine.

Until the end of the fifteenth century, the theories were not supported by evidence; they were eminence-based, not evidence-based. With the gradual development of the scientific method, starting with the idea of discovery, models began to be based on evidence about the relationships between events or different factors. Consequently, investigators began to identify the causes and consequences of specific diseases.

In the mid-nineteenth century, the way to identify the specific agent responsible for an infectious disease became well-established – Koch’s four postulates. They are still used, albeit modified and improved, to account for new knowledge, as described, for example, in a paper by David Fredricks and David Relman.

Over about 150-200 years, many syndromes (i.e., a collection of similar symptoms, signs and other phenomena) were disaggregated into specific disorders with a known cause and natural history. Though new disorders continue to be identified, most progress now concerns refining diagnoses or identifying subdivisions within a disease, such as grading malignant tumours.

As progress was made, the explanatory model became refined and simplified and was increasingly recognised within healthcare and by the public. It was never named, described, or even identified as a model because it slowly emerged without sudden change. In addition, change continued, albeit at a slower rate after 1950.

The healthcare model and theory.

By about 1950, the scientific and public explanatory model used to understand sickness was well-known and widely used. It is now called the medical model; a better name is the biomedical model of illness.

Although not stated, this model is the intellectual basis for many UK National Health Service aspects. However, the model is not a theory expounding the provision and purpose of healthcare services. It is a strong foundation on which a healthcare theory can be built.

The biomedical model of health has two fundament axions:

  • All symptoms are caused by a disease:
    • Symptoms mean any change or alteration in bodily functioning (activities) or experiences (sensation etc.)
    • Disease means a structural abnormality of or in the body (pathology)
  • Symptoms will only arise in the presence of disease. (i.e. they are symptomatic).

Although not intrinsic to the model, other clinical assumptions are inextricably associated with the model:

  • Bodily experiences and functions are separate from and unrelated to the mind
    • The nature of the mind is unclear but includes emotions, beliefs, attitudes, and experiences, such as auditory hallucinations with no bodily explanation.
  • All symptoms a person with a diagnosed disease can arise from the disease are attributed to that disease.
  • Patients only have one disease (this is demonstrably wrong, but the model still assumes that only one disease is pre-eminent)
  • Cure or control of the disease will abolish, or at least reduce, all symptoms.

Last, there are some associated cultural assumptions, first described by Talcott Parsons in 1951 in ‘The Social System’, which introduced the concept of the sick role:

  • The sick person has two rights:
    • To be temporarily exempt from their usual social roles, such as working or looking after the house. The exemption is proportionate to the sickness’s severity.
    • They are not to be blamed or held responsible for their sickness and will consequently be supported by others until they recover.
  • The sick person has two obligations:
    • Consider the sick role undesirable and get well as quickly as possible.
    • Seek expert healthcare help and cooperate fully with any treatment or advice offered.

The biomedical model is the foundation of all healthcare services, despite the apparent fact that, for example, mental health problems are not encompassed by it. Nevertheless, mental health service design, management, and funding have similar axions; all mental health symptoms are due to a single ‘diagnosis’ (presumed abnormality of mental function), and all symptoms indicate an underlying ‘diagnosis’. 

The resultant biomedical healthcare theory is that a person’s symptoms should be investigated until the underlying, causal disease has been established, when a disease-modifying treatment or advice should be given to achieve the best control or cure possible.

To the best of my knowledge, no one has explicitly stated the theoretical underpinning of the healthcare model that is used almost universally. The theory is shown in the figure below.

Biomedical healthcare model

Difficulties in biomedical healthcare.

The theory has yet to be made explicit because everyone grew up with the biomedical model and just accepted the healthcare system based on it. As Priscilla Alderson stressed in 1998, “when theories are implicit, their power to clarify or to confuse, and to reveal or obscure new insights, can work unnoticed,” and, precisely as she said, difficulties arise which are not recognised as arising from a faulty theory. Peter Halligan and I drew attention to the flaws in the biomedical approach 20 years ago, but despite 776 citations, it has not altered practice!

Before considering the weaknesses in the theory, one must acknowledge its success. When a previously healthy person becomes sick and visits a doctor, healthcare based on this theory is often effective. Still, its success rate is declining, and its weaknesses are becoming more troublesome.


The expectation of a single disease diagnosis encourages and almost enforces over-investigation. This may cause harm, increase patient concern, and cause anger or other emotions when no disease is found. At the same time, it prevents considering alternative explanations such as a functional disorder, anxiety or depression, or a ‘normal’ experience with no association with disease. It may delay or even prevent appropriate treatment.

Absence of disease

The absence of a disease challenges healthcare. Any patient with a definite illness who presents with health-related problems and attends healthcare services but where no disease is often stigmatised, disbelieved, or treated with less sympathy. Healthcare staff and services cannot manage such patients because they cannot be categorised, there is no specific curative treatment, and no ‘test’ will make a definite diagnosis. On the other hand, this situation is frequent; 20%-25% of all outpatients and maybe 5% of inpatients fall into this group. Potentially effective therapy may not be given.

Treatment failure.

Treatment failure also challenges healthcare. The expectation that a treatment will cure the disease and remove symptoms is often unmet for many reasons, such as the disease found was unrelated to the symptoms arising from other factors or the symptoms have become embedded in some way (e.g. nocioplastic pain). The resultant risk is that increasing despair leads to the trial of many treatments, often combined, causing considerable iatrogenic harm.

End of disease treatment

Disease treatment is equated to the ending of healthcare responsibility. The patient has significant continuing symptoms after the cure, which is only partial. Yet, the healthcare service states there is no further responsibility on them as they have found and treated the disease. The patient does not appreciate being told they should leave the hospital if they are, for example, significantly disabled. The whole problem of ‘delayed discharge’ arises from this theory interpretation. I have discussed this issue concerning the Reason to Reside criteria and being ready for discharge.

Data quality

Failure to collect appropriate data. The lack of routine data on disability hinders service planning and delivery. There are no data on the number of people discharged from the hospital with incontinence, limited mobility, significantly reduced communication ability, and needing help dressing or cooking, yet all these items are critical when planning community services.

Misuse of disease data

Disease diagnosis data are often misused. All healthcare data collected and used is centred on the disease diagnosis, yet most diseases have a spectrum of severity from minor to severe. Stroke, for example, covers everything from two days of weakness in the arm to a lifetime of a prolonged disorder of consciousness after a subarachnoid haemorrhage. Basing reimbursement on diagnosis on disease diagnosis is unfair because most of the cost arises from associated disability and dependence.

A limited perspective

This theory’s most pervasive and insidious consequence is its effect on broader public policy and resource allocation. It fosters an attitude that society (the State) has fulfilled all its duties of care for sick people.

Society pays no attention to the broader causes of disease and sickness, nor is it concerned with the wider consequences because it concentrates on the individual and their disease. Responsibility for everything else is transferred to the person. A person’s obesity is entirely blamed upon them, not poverty secondary to inadequate wages and social security, not the low quality of the food they can afford, not the easy and cheap availability of alcohol, not the appalling housing available, not the polluted atmosphere, etc.

This theory, which is unwritten but generally accepted, needs to acknowledge the considerable influence of social factors that directly and causally lead to a greater risk of ill health. It also ignores the need to support the person’s adaptation to their new situation or to maximise their return to their previous activities and social roles. These are crucial healthcare responsibilities, yet the theory devalues them because they are inconsistent with the healthcare theory used.

Thus, as predicted by Priscilla Alderson, the implicit theory of healthcare services causes harm, and one particularly significant area of harm is the devaluation of rehabilitation; we are not entirely overlooked, but we are only given a small proportion of the attention and resources needed.


The short-term solution is to develop a general theory of rehabilitation to counter the implicit general theory of healthcare, which only concerns the diagnosis and treatment of disease.

The theory of healthcare is also unsuitable for other services such as mental health and psychiatric services, services for people with learning disabilities, services for older adults, and palliative care services.  Therefore, the longer-term solution is to develop a general theory of healthcare that encompasses the whole range of health, not just disease. This would be a holistic, person-centred healthcare theory.

Comment on this post

Scroll to Top

Subscribe to Blog

Enter your email address to receive an email each time a new blog post is published. 
Then press the black ‘Subscribe’ button.