Is
diagnosis an authoritative statement about a patient’s condition? Does it
involve 100% certainty that this is the correct label for the type of the
patient’s problems, what the underlying causes are for the problems, that this
is the sole problem, what the correct treatment should be, what the outcome is
going to be with and without treatment?
In fact a
doctor’s diagnosis is a summary of a series of possibilities that trigger
further enquiries, not least is the diagnosis correct and should it be changed.
These possibilities inform the doctor’s management plan such as what types of
further tests and examinations the healthcare team should do and when. What are these possibilities?
- What kind of
features does this diagnosis present with? The range of probabilities of how the
diagnosis will present in terms of symptoms, signs, lab tests or other
important clinical features. This will tell the doctor how to recognise
the condition, what information to seek and how. It will guide the doctor
in what questions to ask, how to interpret the answers, what tests to run
and what pattern of results to look for. As noted elsewhere this is a
pattern recognition exercise.
- What if the
diagnosis is wrong? The possibility that the diagnosis is correct (or its’ reliability)
according to some external criteria – usually for most medical
specialties, a test (such as biochemical test, pathology of diseased
organ, imaging test) but could also be another expert doctor’s opinion.
This possibility of the diagnosis made being incorrect means the doctor
should continue to be vigilant for disconfirmatory information i.e.
information that suggests the diagnosis is incorrect. This may be symptoms
or signs or laboratory tests or not responding to a treatment that usually
works or other differences in the clinical picture that are usually
incompatible with the diagnosis or better explained by another diagnosis.
If these arise then the doctor should revise (change) the diagnosis to one
that fits the information better. The doctor keeps a differential
diagnosis (or many differential diagnoses, or even the “null option” of no
diagnosis/ no illness) in mind. For example, a patient with initial
diagnosis of alcohol intoxication but then the doctor notices they have
signs of a subarachnoid haemorrhage and changes the diagnosis to that
instead.
- What other
illnesses could be present? The possibility that other healthcare problems are also present,
known as co morbidity. Like birds of a feather, some illnesses are
associated with other illnesses being present. An illness may increase the
chances of developing another illness . Illnesses have similar underlying
causes thus increasingly the probability of more than one illness. This
alerts the doctor to look for signs or symptoms or run tests or investigations
for these other potential diagnoses. For example if a patient has an unusual
infection diagnosed such as pneumocystis carinii pneumonia this makes the
doctor think that the patient may have an immunocompromised state (immune
system that is very poor at fighting infections) so will run tests looking
for causes of this such as HIV infection as well as taking precautions to
reduce the chances of other infections.
- What
complications should I look out for? Apart from what the doctor has recognized
and identified there can be other problems or features known to be
associated with the diagnosis. This triggers the doctor to look for these
other potential problems through asking the patient for symptoms
indicating the problem is present, examining the patient to look for these
problems and running further tests to identify these problems. Even if the
problems are not present at the initial assessment, they can develop later
so armed with this knowledge the doctor can be alert for them developing
through history taking, clinical examination and running tests in the
future. For example if a patient is seen with a heart attack (myocardial
infarction) there are a variety of complications the doctor will be aware
of and monitor for such as heart failure or cardiac arrest.
- What treatment
should I offer?
The range of possibilities of treatment and the range of responses to
treatment – what are the different alternatives of treatment (not just
medication)/ help available, how likely the diagnosed condition will
respond to treatment, how long this improvement will take, what are the
signs of this improvement taking place and what side effects may occur
with treatment and how to identify these. If the treatment fails and the
diagnosis is correct what are the likely causes for treatment failure
(e.g. maybe not taking the medication or not changing lifestyle factors)
and how to identify them. Further treatment option knowledge is also
triggered at this point. Notice how, as in the above examples, diagnosis
links into other types of knowledge, in this case pharmacology and
treatment guidelines. The doctor can discuss with the patient these
important details and ask them what treatment choices they want to make.
The doctor is reducing the information asymmetry deficit. For example if a
patient presents with high blood pressure the doctor can discuss what the
different options are e.g. lifestyle changes, medication and when to
review them to see if succeeding or what changes in treatment are needed.
- What do I expect
to happen in people with this diagnosis? The range of possibilities of outcomes
seen with this diagnosis. Most illnesses don’t have a fixed outcome but
have a range of probable outcomes. This allows the doctor to discuss these
details with the patient. The range of factors that are associated with
better and worse outcomes are also linked with the doctor’s knowledge
about the diagnosis and allow the doctor to look for the presence of them
and modify them if possible. For example, if a case of cancer is seen the
doctor will try and identify the size of the tumour, whether it has spread
(metastasised) including to local tissues or to lymph nodes or to other
areas of the body. He will also look for other factors that may affect
outcome such as socioeconomic class, other factors that can be modified
e.g. if smoking worsens the outcome of the cancer that can be targeted
with smoking cessation. For some tumours genetic testing of the tumour can
take place to identify targeted treatments.
It can be
seen that diagnosis is provisional and is always open to review as more
information comes to light. It is the hub of linked information that the doctor
has learned about the illness that guides the doctors management plan: what
tests are run, what signs or symptoms are observed for, how to recognize if the
diagnosis is wrong, what other illnesses may also be present, what treatment
options are discussed and chosen, what to expect in terms of outcomes and what
further information is sought to refine the outcome and improve it. Doctors
learn about medicine by learning about a diagnosis and the interlinked
information as described above.
Diagnosis
can be thought of as a quantum reflexive hyperlinked seed. Quantum reflects the
uncertainties as to whether the diagnosis is right, outcome, treatment and so
on. Reflexive in that the information associated with the diagnosis includes
procedures to monitor whether it is accurate or, like the phoenix, be immolated
to be replaced by a new diagnosis. Hyperlinked in that the diagnosis is a hub
that links to multiple domains of information as described above. The seed
describes the compact nature of a simple term like the diagnosis yet jam-packed
with the information and procedures needed to grow a management plan to help
the patient with the right environment of a doctor with the ability to respond
and act on the information from the patient.
