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Introduction to Clinical Reasoning 3
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of such interest to researchers, medical educators, and policy
makers. Improving clinical reasoning outcomes is a patient safety
and healthcare economy priority.
Components of Clinical Reasoning
Several components of clinical reasoning have been identified. A
fundamental one is the application of knowledge to gather and
interpret data in the patient’s history and physical examination.
The purpose is to establish the clinical probability of disease – a
judgement based on the clinician’s knowledge of epidemiology
and what we call evidence-based history and physical examination,
a topic which we explore in Chapter 2. The clinical probability of
disease is a prerequisite for choosing and interpreting diagnostic
tests. Interpreting diagnostic tests is something even qualified
health professionals find difficult [11]. This is because tests lie;
very often, tests give us test probabilities, not real probabilities,
which is why test results have to be interpreted by knowledgeable
clinicians, a topic which we explore in Chapter 3.
Problem representation is something that is neglected in traditional ‘history–examination–differential diagnosis’ teaching
methods, but studies show that being able to represent the problem
before attempting to solve it (i.e., think of a diagnosis) is a key step
in problem-solving, and dramatically increases diagnostic accuracy, especially in more complex cases [12]. This is a skill that can
be learned, and a topic which we explore in Chapter 4.
Clinical reasoning often takes place within teams. Clinicians
also make use of guidelines, scores and decision aids, and co-produce decisions with patients and carers. The important topic of
shared decision-making is explored further in Chapter 5.
Simply knowing about clinical reasoning concepts does not
help people reason better. But it is important for clinicians,
teachers, and learners to have a shared definition, vocabulary and
understanding of clinical reasoning in order to facilitate meaningful discussion and learning. Models of clinical reasoning can
be useful to help us understand the processes underpinning our
decision-making – as clinicians, teachers, and learners. Chapter 6
explores dual process theories which are widely accepted as a
framework with which to understand diagnostic reasoning and
diagnostic error. Some common misunderstandings are identified, and we explore critical thinking, rationality, the different
types of knowledge used by Type 1 and Type 2 processing, and
thinking about one’s own thinking (metacognition).
The topic of cognitive biases in clinical reasoning is controversial. This is partly because there are several key fallacies in the
received view of dual process theories. There is definitely
agreement that cognitive biases exist in medicine, but disagreement as to whether they are a significant source of diagnostic
errors compared with knowledge deficits. Chapter 7 explores this
topic further using a case history and analysis.
Clinical reasoning does not exist solely inside a clinician’s
organised cognitive structures but is entangled in the activity of
providing care for the patient [13]. Chapter 8 explores ‘situativity’
and human factors (the science of the limitations of human
performance). ‘To err is human’, therefore in order to minimise
errors, we need to focus on improving processes, systems, and
technology, as well as education and training in cognitive strategies. Pat Croskerry explores metacognition and cognitive strategies further in Chapter 9.
Finally, we look at teaching clinical reasoning in Chapter 10.
There is no evidence that teaching clinical reasoning concepts
alone, or short courses, improves clinical reasoning ability. The
most effective way to teach clinical reasoning is to use strategies
that build knowledge and understanding, and to practice with as
many different cases as possible in as many different contexts as
possible with coaching and feedback. We explore key concepts in
teaching clinical reasoning, specific evidence-based strategies
that teachers can use, and describe one approach to introducing a
clinical reasoning curriculum at undergraduate level.
How Does Expertise in Clinical Reasoning
Develop?
If how clinicians think, reason, and make decisions is arguably their
most critical skill, it is useful to consider how expertise in clinical
reasoning develops. In the 1970s, expertise in medicine was thought
to be related to superior general thinking skills. However, when
researchers observed experts and novices, they found there was no
difference in the processes or thinking strategies used – both
quickly came up with one or more diagnostic hypotheses which
guided the search for further information. Experts were more accurate because they knew more, and because the knowledge of experts
varied from case to case, their performance varied from case to case
as well [14]. This led to researchers changing direction and examining the role of knowledge in medical expertise.
One of the next questions for researchers was, do experts have
bigger, better memories? The answer was no – given unlimited
time, novices can remember as much as experts about a clinical
case on paper. But experts appear to acquire information more
efficiently and pay attention to more critical information (you
have probably seen this in action). In a series of well-known
experiments, Chase and Simon showed chess players of varying
strength – from master to novice – chessboards set up as if in the
middle of a game for only 5 seconds and then asked them to
reconstruct the position of 28 pieces on a blank chessboard immediately afterwards. What they found was the chess masters showed
a remarkable ability to reconstruct the board almost perfectly,
whereas the novices could only recall the position of four or five
pieces. However, when the experiment was repeated with the
chess pieces arranged randomly, chess masters performed no
better than anyone else [15]. Chase and Simon concluded that
chess masters had stored in memory a large number of recognisable ‘chunks’, or meaningful patterns (see Box 1.4). Similar results
have been found in other fields – experts can reconstruct a briefly
examined scene provided it portrays a realistic (as opposed to
random or meaningless) pattern. But pattern recognition by itself
does not explain expertise. Non-chess players can be trained to
memorise chess patterns. Experts recognise patterns of high sig-
nificance because of their formal as well as experiential knowledge
of chess – in other words, they study [16].
4 ABC of Clinical Reasoning
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We know that knowledge is fundamental to expertise in clinical
reasoning. (As we will see in Chapter 6, other things matter as
well.) But by knowledge, we do not mean only facts. That is like
saying the raw ingredients are the same as the cake. Figure 1.2
refers to different types of knowledge; all these types of knowledge
matter in clinical reasoning.
With learning, the process of chunking and automating, as
described in Box 1.4, frees up mental resources. The difference
Metacognitive
• Knowledge of cognition in general as well as
awareness of one’s own cognition
Procedural
• How to do something, methods of inquiry, and
criteria for using skills, algorithms, techniques, and
methods
Conceptual
• The inter-relationships among the basic elements
within a larger structure that enable them to
function together
Factual
• The basic elements learners must know to be
acquainted with a discipline or solve problems in it
Figure 1.2 Different types of knowledge. Adapted from: A model of
learning objectives–based on: a taxonomy for learning, teaching, and
assessing: a revision of Bloom’s Taxonomy of educational objectives by Rex
Heer, Center for Excellence in Learning and Teaching, Iowa State University.
https://www.celt.iastate.edu/teaching/effective-teaching-practices/
revised-blooms-taxonomy (accessed April 2022).
Box 1.4 Chunking and automating: how we can think more
complex thoughts
Human working memory can only process a limited number of
elements at a time. But not all elements are created equal. The
elements of information stored in our long-term memory increase in
complexity over time, with smaller elements combining to form
larger ones. This process is called ‘chunking’ and it is what allows us
to think more complex thoughts.
For example, a child who has not yet learned the alphabet will see
the letter ‘H’ as three straight lines. Reproducing these three straight
lines correctly could be a cognitively demanding task. Over time,
they will chunk and automate drawing the letter ‘H’ until it becomes
effortless. Once they have mastered individual letters, whole words
will still be new to them. The word ‘H, o, u, s, e’ will consist of five
separate elements. But over time, this will be chunked as the word
‘House’ in long-term memory which can then be read and written
effortlessly.
Chunking and automation is a result of learning. Experts store
knowledge in long-term memory as rich chunks called schemas
which allows them to overcome the limitations of working memory
when solving problems. (See Chapter 10 for information on how
teachers can facilitate the process of schema formation.)
Adapted from Lovell O. Sweller’s cognitive load theory in action. A
John Catt Publication, 2020. pp. 20.
between normal learning and expert learning is what people do
with those freed up resources. People who become experts reinvest their mental resources in further learning. They seek out
more difficult problems. They tackle more complex representations of common problems. They continue to work at the edge of
their competence [17].
In summary, we know that expertise in clinical reasoning is
highly dependent on knowledge, but that is not the whole story.
We will explore this further in Chapters 6 and 10.
Clinical Reasoning through Different
Lenses
At its most basic level, clinical reasoning is to do with knowledge,
how knowledge is organised in long-term memory as mental representations, and the cognitive processes responsible for storing,
transforming, and retrieving these. This view of clinical reasoning
is important for learners, who must have a) a deep foundation of
factual knowledge, b) understand facts and ideas in a conceptual
framework, and c) organise their knowledge in a way that facilitates retrieval and application. (The latter two points are why we
need expert teachers.) However, clinical reasoning is also
something that is ‘situated’ in the environment. Thinking and
learning is context-dependent, the result of multiple dynamic
interactions between individuals and the environment. Cognition
is also distributed in team members and in non-humans (e.g.,
computers). It can be adversely affected by poorly designed technology and systems, as well as sleep deprivation, fatigue, and
excessive workload. Understanding clinical reasoning through
this lens is important too. But sometimes we need to be able to go
beyond the ‘content’ and make sense of the patient’s illness (and
our own response to it) and understand the practice of medicine
in its wider socio-cultural context. This is what we sometimes call
the ‘art’ of medicine, which involves crafting a wise and deliberate
course of action appropriate for the circumstances and may not
involve any technical decision-making at all. Clinical reasoning
through this lens is often what postgraduates are able to start
practicing once their mental resources are freed up from focusing
on the technical aspects of medicine. Many studies demonstrate a
correlation between effective clinician–patient communication
and ‘whole person care’ with improved health outcomes. An
example of this is given in Box 1.5.
Listen to Me; I Am Telling You My Diagnosis
Whatever their level of health literacy, no patient is an empty
vessel devoid of knowledge or insight about their own condition.
By presenting to a clinician, patients have often engaged in their
own reasoning and formulated ideas about a diagnosis or even
several diagnoses. The patient’s perspective is not simply a psychosocial one but may include relevant insights into anatomical
and physiological changes and pathology (see Box 1.6). This does
not mean they are always correct – that is why they attend a clinician – but neither is their perspective irrelevant.
While the clinician arrives at a differential diagnosis (and/or
problem list) following the history, or patient interview, the patient
arrives with their own differential diagnosis (and/or problem list).
Introduction to Clinical Reasoning 5
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Box 1.5 The importance of whole person care
Two patients had similar symptoms. They were experiencing
transient numbness of different parts of the body – one side of the
face or the other, sometimes the arm or hand. These symptoms
were causing a great deal of anxiety. The patients went to see two
different physicians.
The first patient told his story. At the end of the consultation the
physician said, ‘Well you’ve either got migraine or multiple sclerosis
so we’ll do an MRI scan and I’ll let you know the results.’ He was
not given a further appointment. While waiting for his MRI scan, his
anxiety and symptoms increased significantly.
The second patient told her story. Recognising that these
symptoms are common in stress and did not fit any neurological
pattern, the physician said, ‘I see lots of people with these
symptoms and very often it’s because they are working too hard,
not sleeping, or under stress. Even though they might not realise
they are stressed, their body is telling them they’re stressed. Tell me
about your schedule and what’s going on in your life.’ The patient’s
husband looked at her knowingly and sure enough there were lots
of stressors related to work and home that had been an issue. An
MRI scan was arranged, but the patient was advised to make
changes to her lifestyle and her symptoms resolved.
Both patients had normal MRI scans. Explanation and good
communication lead to better outcomes, greater compliance with
recommended treatments, and less re-attendances.
Box 1.6 A patient-centred approach to differential diagnosis
Agreeing the differential diagnosis
Patient’s differential Doctor’s differential
Leading hypothesis
• Leading hypothesis
Alternative 1
•
•
Alternative 2
……
•
•
‘Must-not-miss’
Where is the common understanding?
‘Let us think about this together’
Eventual diagnosis must explain both parties’ data
The history, or patient interview, is a discussion of the patient’s ideas
and insights into their symptoms and diagnosis. The clinician’s role is
crucial to the correct synthesis of this information, but this must be
done with a complete dataset elicited from the patient.
•
•
Alternative 1
Alternative 2
•
•
……
‘Must-not-miss’
•
Patients describe their own insight with differing levels of articulacy, but all patients do this. Clinical reasoning should from the
outset be a collaborative and dynamic process between patient and
clinician (see Box 1.7). The benefits include identifying the
patient’s priorities to the eventual goal of shared decision-making.
Yet, how often do we hear, either in a media story, complaint, or
adverse event, that the clinician ‘wouldn’t listen to what we were
saying’? This feeling among patients of dissonance between clinicians and themselves is reflected by the evidence base [18–20].
Assessing the patient’s own starting point by defining their own
understanding and experience of their symptoms at the beginning
of the interview is crucial to avoiding diagnostic error.
Box 1.7 The patient presents after reasoning through their
symptoms
‘Thank you for speaking to me doctor. I’ve been feeling unwell for
several days. My hay fever is usually bad at this time of year. I know
the pollen count is high at the moment, but my usual medication is
not working. My nose is blocked, and I’ve been sneezing.
My chest is tight as well and I’ve been coughing more at night.
My blue inhaler has helped but I’m using it more than usual and it’s
not as effective. My peak flow is down. I was wondering if I need
some steroids as well.
I was shielding during the first lockdown, and I know COVID is
coming back again. Do I need another jab to boost my immunity?’
Patient’s problem list:
My hay fever is not controlled
1.
2. My asthma is deteriorating
3. The prevalence of COVID-19 is increasing. Do I need further
immunisation?
There is a lot of data to unpack here to make the diagnosis and
answer the patient’s concerns.
The different lenses through which we can view clinical
reasoning, whether from the clinician or the patient’s perspective, are not mutually exclusive. There are situations that call for
rapid technical responses, for example, emergencies. Then there
are others that call for time, wisdom, and care. Clinical reasoning
is complex and takes years to learn. The challenge for educators
is to provide clinical environments with multiple tasks and
strategies in order to equip learners over time to be able to
reason through a variety of clinical problems as effectively as
possible [21].
Summary
At the time of writing, most medical schools and postgraduate
training programmes provide instruction in the basic elements of
the diagnostic process. However, students and trainees largely
learn the knowledge, skills, and behaviours required for effective
clinical reasoning implicitly and ad hoc, through experience and
apprenticeship. Yet a lack of clinical reasoning ability has been
shown to be a major cause of diagnostic errors resulting in
significant preventable harm to patients worldwide. There is a
growing consensus that medical schools and postgraduate
training programmes should teach clinical reasoning in a way
that is explicitly integrated into courses throughout each year of
the programme, adopting a systematic approach consistent with
current evidence.
For teachers and learners, it can be useful to think of clinical
reasoning as a process made up of different components, each of
which requires specific knowledge, skills, and behaviours. These
components are what the following chapters explore in more
detail. If we can start with an understanding of what clinical
reasoning is, why it is important, what the key components are,
and how it develops, we are in a better position to create clinicians
who are good decision makers and who ultimately provide better
care for patients.
6 ABC of Clinical Reasoning
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References
1. Croskerry P. Clinical decision making. In: Barach P, Jacobs J, Lipshultz S,
and Laussen P (Eds). Pediatric and Congenital Cardiac Care. London:
Springer, 2015. https://doi.org/10.1007/978-1-4471-6566-8_33 (accessed
April 2022).
2.
DID-ACT Project. Developing, implementing, and disseminating an
adaptive clinical reasoning curriculum for healthcare students and educators. An EU funded project, 2020. https://did-act.eu/home/project
(accessed April 2022).
3.
Cooper N, Bartlett M, Gay S et al. On behalf of the UK Clinical Reasoning
in Medical Education (CReME) consensus statement group. (2021).
Consensus statement on the content of clinical reasoning curricula in
undergraduate medical education. Medical Teacher; 43(2): 152–159.
Tehrani ASS, Lee HW, Mathews SC et al. (2013). 25-year summary of US
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malpractice claims for diagnostic errors 1986-2010: an analysis from the
National Practitioner Data Bank. BMJ Quality & Safety; 22(8): 672–680.
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Graber ML. (2013). The incidence of diagnostic error in medicine. BMJ
Quality & Safety; 22(Suppl 2): ii21–ii27.
Leape LL, Berwick DM and Bates DW. (2002). Counting deaths due to
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medical errors. [Letters]. JAMA; 288(19): 2405.
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internal medicine. Archives of Internal Medicine; 165: 1493–1499.
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diagnosis in health care. Washington (DC): The National Academies
Press, 2015. doi:10.17226/21794 (accessed April 2022).
Shwarz A, Landon B, Elshaug A et al. (2014). Measuring low value care in
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Medicare. JAMA Internal Medicine; 174(7): 1067–1076.
10. Berwick D and Hackbarth A. (2012). Eliminating waste in US
healthcare. JAMA; 307(14): 1513–1516.
11. Whiting PF, Davenport C, Jameson C et al. (2015). How well do health
professionals interpret diagnostic information? A systematic review.
BMJ Open; 5(7): e008155.
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Bordage G. (1994). Elaborated knowledge: a key to successful diagnostic
thinking. Academic Medicine; 69(11): 883–885.
13. Koufidis C, Manninen K, Nieminen J et al. (2022). Representation,
interaction, and interpretation. Making sense of the context in clinical
reasoning. Medical Education; 566: 98–109.
Elstein AS, Shulman LS and Sprafka SA. Medical problem solving. An
14.
analysis of clinical reasoning. Harvard University Press, 1978.
15. Chase WG and Simon HA. (1973). Perception in chess. Cognitive
Psychology; 4: 55–81.
16. Bereiter C and Scardamalia M. Experts are different from us: they have
more knowledge. In: Surpassing ourselves: an inquiry into the nature and
implications of expertise. Open Court Publishing, 1993. pp. 25–42.
Bereiter C and Scardamalia M. Expertise as a process. In: Surpassing
17.
ourselves: an inquiry into the nature and implications of expertise. Open
Court Publishing, 1993. pp. 77–120.
18.
Fransen GAJ, Janssen MJR, Muris JWM et al. (2007). Measuring the
severity of upper gastrointestinal complaints: does GP assessment
correspond with patients’ self- assessment? Family Practice; 24: 252–258.
Dorval E, Rey JF, Soufflet C et al. (2011). Perspectives on gastroesopha-
19.
geal reflux disease in primary care: the REFLEX study of patient-physician agreement. BMC Gastroenterology; 11: 25–33.
20. Humphrys E, Walter FM, Rubin G et al. (2020). Patient symptom
experience prior to a diagnosis of oesophageal or gastric cancer: a
multi-methods study. BJGP Open; 4(1): bjgpopen20X101001.
21. Eva K. (2004). What every teacher needs to know about clinical
reasoning. Medical Education; 39: 98–106.
Further Resource
1. Bereiter C and Scardamalia M. Surpassing ourselves: an inquiry into the
nature and implications of expertise. Open Court Publishing, 1993.
CHAPTER 2
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Evidence-based History and Examination
John Frain
OVERVIEW
• The history and physical examination are essential diagnostic tools
• To formulate a differential diagnosis, the history should identify
the patient’s key presenting symptoms and associated symptoms
The patient’s background and the natural history of a condition
•
are essential contextual factors in making a correct diagnosis
• An incomplete physical examination increases the risk of diagnostic error
• If available, likelihood ratios are a measure of diagnostic accuracy
which are easy to understand and apply at the bedside
• Clinical teachers should be familiar with evidence-based history
and examination
Introduction
Evidence-based history and examination surveys all data from
the clinical encounter, compares it to available evidence, including
recognised diagnostic standards, and quickly identifies those variables with the greatest diagnostic accuracy.
Around 80% of diagnoses are made from the history alone [1].
Its importance is such that Hampton et al. recommended more
emphasis should be placed on teaching students accurate historytaking and more emphasis should be placed on research into
communication between patients and clinicians [1]. The purpose
of the history is the generation of a differential diagnosis broad
enough to include the actual diagnosis but focussed enough to be
tested by an appropriate physical examination, and investigations
when necessary. The differential diagnosis consists of a leading
hypothesis and two or three other hypotheses including any ‘must
not miss’ diagnoses, all justifiable by the data gathered, and taking
into account the patient’s own concerns. Generating a differential
diagnosis guards against premature closure (see Chapter 9). For
the learner, it aids in developing their clinical reasoning ability.
Generating a differential diagnosis needs to be taught alongside
the history and physical examination, not separately. This chapter
will introduce the idea of evidence-based history and physical
examination, an important component of clinical reasoning.
The Evidence Base
Most of our knowledge of history and physical examination predates the development of evidence-based medicine, and from a
time when patients presented later in the course of their illness,
usually with more ‘classic’ features. Nowadays, especially in developed countries, clinical problems present earlier and are often less
well differentiated from one another. We know that many single
features in the history and physical examination are limited in
their usefulness (e.g., whether someone’s chest discomfort is
‘central and crushing’ or not; or whether Kernig’s sign is present).
Nonetheless, good quality evidence now exists, including
systematic reviews of symptoms and diagnostic accuracy studies
of physical signs. This is being assimilated into textbooks (see
further resources) that provide epidemiological and qualitative
data as well as diagnostic accuracy studies including sensitivities,
specificities, and likelihood ratios. Where statistical evidence is
lacking, authors provide diagnostic guides based on the best
available epidemiological evidence. Evidence-based principles
and knowledge can be reinforced for learners through reflective
coursework (see Box 2.1) which can further enable reflection on
clinical reasoning during workplace training.
Exploring Symptoms: Combining Process
and Content
The process of history-taking cannot be separated from
knowledge of epidemiology, anatomy, and physiology. Nor can it
be separated from effective communication with patients [1].
Irrespective of the cause, each patient seen by a clinician is essentially saying: ‘I’ve noticed some changes in my anatomy and physiology. Can you tell me, is this normal, part of getting older or is it
pathology? If it’s pathology, will I return to my previous health,
will it leave me with some loss of function or could it even shorten
ABC of Clinical Reasoning, Second Edition. Edited by Nicola Cooper and John Frain.
© 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.
8 ABC of Clinical Reasoning
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Box 2.1 Reflective coursework: the presentation of chest pain
in women
‘I encountered a female patient in her 50s presenting with a
possible acute coronary syndrome (ACS). We had recently been
discussing in clinical skills about possible differences in the
presentation of acute coronary syndrome in women and men. I
decided to examine the evidence for this.
I undertook a systematic search of the literature using the 6S
evidence pyramid we had been taught. I identified 16 relevant
studies using the SORT criteria.
recording and analysis across the studies. However, I was able to
draw the following conclusions:
• Women are more likely to present with ACS atypically compared
to men
• Men are more likely to present with chest pain than women
• Chest pain is the most common symptom presentation for both sexes
• Younger women are more likely than older women to present
with typical symptoms
• No difference exists between sexes for prevalence of chest pain
and/or other typical symptoms of ACS
• Women reported more associated (non-chest pain) ACS
symptoms than men
Continued development as a clinician requires three things:
reflective practice, unwavering curiosity, and maintaining an open
mind to new evidence and ideas. Writing this essay has highlighted
the importance of looking to the highest level of evidence for
guidance, while maintaining a healthy level of scepticism for the
recommendations by analysing the primary literature and systematic
reviews behind them.’
i. Ebell MH, Siwek J, Weiss BD et al. (2004). Strength of recommenda-
tion taxonomy (SORT): a patient-centered approach to grading
evidence in the medical literature. Am Fam Physician; 69(3): 548–56.
This is an excerpt from a patient-based piece of coursework
undertaken by graduate entry medicine students at the University of
Nottingham, UK. Students examine the evidence underlying a
clinical feature encountered in practice.
i
There was heterogeneity of data
my life?’ Clinical reasoning and decision-making is required to
assess all these concerns.
Models for clinical communication have been developed, most
notably the Calgary-Cambridge model [2] consisting of 70 skills
which facilitate accurate history-taking (see Box 2.2). Teaching
this model involves deliberate practice with detailed, specific
feedback by observers. It is used either one-to-one with a tutor
and patient, with patient actors, or at the bedside with real
patients. An adapted form of the observation guide includes
feedback on elements of clinical reasoning [3, 4].
When taking a history, key symptoms emerge within the relevant system (see Box 2.3). While symptoms may overlap different
systems (e.g., chest pain could be cardiac, musculoskeletal, or
respiratory in origin) or be challenging for both patient and doctor to define (e.g., dizziness), many diseases present with varying
configurations of key symptoms within the relevant system.
Provided the clinical setting of an individual symptom is clearly
defined (e.g., nausea and vomiting in patients with suspected
intestinal obstruction, or chest pain in patients with suspected
myocardial infarction in the emergency department) it is possible
Box 2.2 The Calgary-Cambridge model: the process required
for accurate history-taking
The patient’s opening statement (usually 30–120 seconds)
•
• Identifying a problem list
• Agreeing an agenda for the interview
• Exploring each symptom experienced by the patient
present
• Exploring the patient’s relevant background information
• Ensuring all the patients concerns have been addressed
• Explanation and planning
• Shared decision-making
Adapted from Silverman J, Kurtz SM, Draper J. Skills for
Communicating with Patients, 3rd edn. CRC Press, 2013.
Box 2.3 Summary of key symptoms by body system
General Cardiovascular
Fatigue/malaise
Fevers/rigors/night sweats
Weight/appetite
Sleep disturbance
Rashes/bruising
Respiratory Alimentary
Pain
Breathlessness
Wheeze
Cough
Sputum/haemoptysis
Genitourinary Nervous system
Frequency
Dysuria
Incontinence
Change in urinary volume
Prostatic symptoms
Menstrual symptoms
Musculoskeletal
Pain
Stiffness
Swelling
Loss of function or activities of daily living
Adapted from the Calgary-Cambridge Guide. In: Silverman J, Kurtz S
andDraper J. Skills for Communicating with Patients, 3rd edn. CRC
Press, 2013.
Pain
Breathlessness
Palpitations
Swelling
Difficulty swallowing
Nausea/vomiting/haematemesis
Indigestion/heartburn
Pain/distension
Change in bowel habit
Bleeding
Headache
Loss of consciousness
Dizziness
Visual disturbance
Hearing
Weakness
Numbness/tingling
Memory or personality change
Anxiety/depression
to reason its significance and thus its usefulness as evidence of the
presence of the target condition. Course content can be developed
to teach students the evidence-base for each symptom alongside
the process of exploring symptoms with the patient (Box 2.4).
Evidence-based History and Examination 9
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Box 2.4 Summary evidence box for cardiovascular pain
Definition
Impairment of the blood supply to the heart. Pain is precipitated by
exertion and relieved by rest.
Anatomical site
Narrowing of the coronary arteries, usually by atherosclerosis but
occasionally by spasm.
Pathophysiology
Primarily, smoking, high cholesterol, high blood pressure, and
diabetes damage the endothelial lining of the coronary arteries.
What does the patient say?
‘I keep getting pains in my chest whenever I do things.’
‘My angina is getting worse.’
Evidence base
The table shows the European Society of Cardiology clinical
classification of angina:
Typical angina Meets all three of the following characteristics:
Atypical angina Meets two of the above characteristics
Non-cardiac chest
pain
i
1.
Characteristic retrosternal chest discomfort –
typical quality and duration
2. Provoked by exertion and emotion
Relieved by rest or GTN (glyceryl trinitrate) or both
3.
Meets one or none of the above characteristics
Defining Symptoms
Patients and clinicians do not always agree on how a symptom is
experienced. Learners benefit from realising and exploring this at
the outset. Misunderstandings can occur more readily when
symptoms appear to overlap body systems and/or when there are
multiple causes. An example is dizziness, where one classification
lists 33 possible causes. Students, in particular, worry they, ‘Don’t
know what questions to ask’. Providing knowledge and categorising the underlying causes of symptoms can enable students to
explore and define the symptoms further:
Patient:‘I feel dizzy.’
Student:‘What do you mean by that?’
Patient:‘I feel I’m going to pass out sometimes’ – pre-syncope
‘I feel as though I’m (or the room is) moving’ – vertigo
‘I feel as though I’m falling’ – disequilibrium (often
neurological)
‘I feel light-headed all the time’ – possible anxiety or
depression
Similarly, misunderstandings regarding ‘indigestion’ can be clarified by using the patient’s own definition as the starting point (see
Box 2.5). In the case of upper alimentary symptoms, agreement
between patient and clinician on the patient’s experience is critical to the diagnosis, including malignancy.
Up to 95% of chest pain presents in primary care.ii Of patients
presenting with chest pain at the emergency department, almost a
third have serious cardiovascular disease. Only 11–44% of patients
referred to the cardiology out-patients have coronary artery disease.
The presence of atypical symptoms such as pain worse on
inspiration, stabbing pain, positional, reproducible on palpation of the
chest wall and no radiation is more useful in identifying patients who
do not require investigation (positive predictive value=0.94) than are
the features of typical angina in identifying patients who do require
further investigation (positive predictive value=0.21). In stable chest
pain, the patient’s own description of the pain is the most important
predictor of coronary heart disease, and in acute pain, the history of
chest pain should be judged alongside the ECG findings.
Chest pain in a young person is unlikely to be coronary artery
disease but you should ask about associated dizziness, syncope, and a
family history of sudden death as well as screen for risk factors.
Women present more often with atypical angina. They are more likely
than men to have pain at rest, during sleep or precipitated by stress.
References
i. Talley NJ, O’Connor S. Clinical Examination, 7th edition. Sydney:
Churchill Livingstone, 2014.
ii. Polmear A. Evidence-Based Diagnosis in Primary Care.
Edinburgh: Butterworth Heinemann, 2008.
iii. Buntinx F, Knockaert D, Bruyninckx R et al. Chest pain in general
practice or in the hospital emergency department: is it the
same? Fam Pract (2001) 18:586–589.
iv. Chun AA, McGee S. Bedside diagnosis of coronary artery
disease: a systematic disease. Am J Med (2004) 117:334–343.
Adapted from Frain J. Module 3 Clinical Skills Workbook:
Cardiovascular. Graduate Entry Medicine, University of
Nottingham, UK.
iv
Associated Symptoms
Many students are proficient at obtaining a detailed description
of a presenting symptom but fail to explore associated symptoms.
iii
By associated symptoms, we mean those symptoms which,
though subsidiary to the patient’s main concern (e.g., pain), are
nonetheless present and may contribute to the patient’s overall
concern about the diagnosis. The main associated symptoms for
any presenting symptom most commonly arise from the same
organ system as the presenting one (see Box 2.3). A patient presenting with a cough may be concerned about the inconvenience
of the cough and the impact on their ability to function. However,
the diagnosis is not apparent from this symptom alone. For
example, diagnosing pneumonia requires enquiry about sputum,
fever, breathlessness, chest pain, and haemoptysis. Having to
present the history at the end of the interview and getting the
student to list the problems and formulate a differential diagnosis forces students to use associated symptoms in their
reasoning [5] (see Box 2.6).
Interpreting Features in the History
Studies of the history have assessed which features might be
more diagnostic than others for a particular condition. One
looked at what features of the history in chest pain are most helpful to clinicians in differentiating cardiac from non-cardiac
causes [6]. The authors found no single element of the chest pain
history was a powerful enough predictor of non-cardiac pain to
allow a clinician to decide on history alone, but researchers have
attempted to combine features in the history which can be of use
in clinical practice (see Box 2.7). Pain that is stabbing, pleuritic,
positional, or reproducible by palpation has likelihood ratios
10 ABC of Clinical Reasoning
https://t.me/medicina_free
Box 2.5 Patient perspectives on upper alimentary tract symptoms
Under CC BY 4.0. Humphrys E, Walter FM, Rubin G et al. (2020). Patient symptom experience prior to a diagnosis of oesophageal or gastric
cancer: a multi-methods study. BJGP Open; 4 (1): bjgpopen20X101001. https://doi.org/10.3399/bjgpopen20X101001.
near zero, meaning the likelihood of this kind of pain being
cardiac is very low. Conversely, chest pain that radiates to one or
both shoulders or arms or is precipitated by exertion has higher
likelihood ratios (LR = 2.3 − 4.7) meaning this kind of pain is
more likely to be cardiac. Likelihood ratios are discussed in more
detail later.
Natural History and Context
The natural history of a disease is the sequence of changes occurring within the body from the beginning of the illness until its
resolution. The disease resolves to either complete restoration of
health, to loss of function, which may also be progressive, or the
patient’s death. Familiarity with the symptoms and signs of a
Evidence-based History and Examination 11
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Box 2.6 The importance of associated symptoms is formulating
a reasoned diagnosis
‘Mr. Jackson had a car crash yesterday when his car was hit from
behind. The pain (presenting symptom) is worse today and he has
been taking paracetamol and ibuprofen. A hot water bottle has
helped to relieve his symptoms, but he has been unable to use his
keyboard at work. I think he has whiplash.’
Exploring the mechanism of injury, the radiation of pain and the
presence of sensorimotor deficit clarifies the diagnosis: ‘Mr. Jackson
was hit from the left yesterday just after he had got into his car.
Unfortunately, he had not put his seatbelt on. He was thrown
against the door and then rebounded back again into his passenger.
He felt a sudden pain on the right side of his neck. His pain is worse
this morning. Mr. Jackson describes pain radiating to his right
shoulder. His arm feels heavy and weak (associated symptom). He
has tingling down his arm to his right thumb (associated
symptom), in the C6 dermatome. I am concerned he has a
hyperextension injury and right C6 nerve root irritation.’
Adapted from Bokshan SL, DePasse JM, Eltorai AE et al. (2016). An
evidence-based approach to differentiating the cause of shoulder
and cervical spine pain. Am J Med; 129(9): 913–8.
Box 2.7 Differentiating cardiac from non-cardiac chest pain by
history
• Low risk of cardiac pain: the 3 P’s – pain that is pleuritic or
stabbing, positional, and reproduced by palpation
• Probably low risk: pain not related to exertion that occurs in a
small inframammary area of the chest wall
• Probably high risk: pain described as pressure, similar to a
previous heart attack/angina or accompanied by nausea,
vomiting, and diaphoresis
• High risk: pain that radiates to one or both shoulders or arms or is
related to exertion
When combined with the patient’s age, sex, and past medical
history, it should be possible to accurately identify those at low risk
of cardiac pain, although these are a minority of patients who
present to hospital with chest pain. Other serious causes of the
chest pain still need to be considered.
Adapted from Swap CJ and Nagurney JT. (2005). Value and
limitations of chest pain history in the evaluation of patients with
suspected acute coronary syndromes. JAMA; 294 (20): 2623–9.
condition facilitates its diagnosis. The classical presentation of
disease as described in textbooks is quite uncommon. Some
symptoms and signs occur early in the disease while others occur
later. For example, in early heart failure, the patient may become
breathless only on severe exertion. Later, breathlessness occurs on
more moderate exertion (e.g., climbing the stairs), while later the
patient has a problem lying flat in bed (orthopnoea) and may be
breathless at rest.
If a learner interviewing a patient with breathlessness believes
the symptoms of orthopnoea must be present for heart failure to
be diagnosed, they will miss patients in the earlier stages of disease who may benefit from proven treatment. This combination
of the patient’s symptoms and the natural history of the condition
is reflected in the New York Heart Association’s functional
classification of heart failure (see Box 2.8). The correlation of each
class with echocardiographic findings can be used to guide evidence-based therapy.
This concept can be demonstrated to students with a simple
class exercise of constructing the natural history of a peritonsillar abscess (quinsy). All will have experienced a viral sore
throat, many will have experienced bacterial tonsillitis, and a
few suffered a quinsy. Discussion of the symptoms from onset
to recovery provides the group with appreciation of the natural
history of a condition and its relevance to clinical reasoning
(see Box 2.9).
Similarly, students who are taught lists of features of various
diseases are not as accurate at diagnosis compared with those
taught probabilities of symptoms being present [7]. For example,
nearly all adult patients with meningitis in the UK have headache
and a fever at presentation, the next most common symptom is
nausea and vomiting (70%), but only around half complain of
photophobia and a stiff neck [8]. Severe, or late bacterial, meningitis, on the other hand, is associated with prototypal symptoms
and signs as described in textbooks. Simply teaching prototypes
and ‘medical triads’ is likely to encourage superficial pattern recognition that results in overconfidence, premature closure, and
incorrect diagnosis.
The patient’s context, including age and gender, should be
emphasised when considering the clinical probability of a disease.
Epidemiological studies provide learners with an evidence base to
assist in their clinical reasoning. For example, the Interheart
Study [9] found over 90% of all patients suffering their first myocardial infarctions had the risk factors of smoking, hypertension,
diabetes, abdominal obesity, low physical activity, and poor diet.
Box 2.10 shows the percentage pre-test probability for American
Box 2.8 New York Heart Association Functional Classification
of Heart Failure – correlation of symptoms, echocardiographic
findings, and therapeutic options
Class I II III IV
Symptoms None On
Ejection
fraction
Use these
drugs
Adapted from The Criteria Committee of the New York Heart
Association. Nomenclature and criteria for diagnosis of diseases of the
heart and great vessels 9th edn. Little, Brown & Co, 1994. pp. 253–256.
40–50% 30–40% <30% <30%
ACE inhibitor
Beta-blocker
moderate
activity
ACE
inhibitor
Beta-blocker
Low-dose
diuretic
Statin
On
mild
activity
ACE inhibitor
Beta-blocker
Diuretic
Spironolactone
Digoxin
Statin
Sacubitril/
valsartan
At rest and on
minimal
activity
ACE inhibitor
Spironolactone
Digoxin
Diuretic
Beta-blocker (if
compensated)
Sacubitril/
valsartan
12 ABC of Clinical Reasoning
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Box 2.9 Discuss with your colleagues a possible natural
history of a peritonsillar abscess (quinsy)
Students will usually come up with the following list, as it within
their own experience:
•
Feverish
• Sore throat
• Neck pain
• Pain on swallowing
• Yellow spots on the tonsils
• Neck swelling
• Unable to eat or drink/throat feels blocked
• Generally unwell
Key discussion points:
• Early disease is undifferentiated
• Not every sore throat leads to a quinsy
• Early disease can be difficult to differentiate from serious disease –
hence the importance of red flags
• Signs with higher LRs are likely to occur later in the disease
Red flag/serious symptoms can be used for safety netting/shared
•
decision-making – explanation to the patient about the possible
course of events
Box 2.10 Estimating the pre-test probability (%) of coronary
heart disease
Age Non-anginal
chest pain (%)
MF MF MF
30–39 3–35 1–19 8–59 2–39 30–88 10–78
40–49 9–47 2–22 21–70 5–43 51–92 20–79
50–59 23–59 4–25 45–79 10–47 80–95 38–82
60–69 49–69 9–29 71–86 20–51 93–97 56–84
Atypical
angina (%)
Typical
angina (%)
In summary, exploring and defining symptoms, including
associated symptoms, has to be accompanied by knowledge – of
the underlying causes of symptoms, what particular features, or
combination of features, are helpful in making a diagnosis, the
natural history of disease, probabilities (rather than lists) of
symptoms associated with various diseases, and epidemiology.
The process of history-taking illustrated in Box 2.2 is designed to
obtain accurate data, the content of which can then be interpreted
by the clinician.
The Physical Examination
While the history is the key component in formulating a diagnosis, the physical examination, used in conjunction, can double
the diagnostic power of the history [10]. Inadequate physical
examination, mostly failure to perform one at all, is a preventable
source of medical error [11]. Despite these facts, there are welldocumented deficiencies in the basic clinical skills of historytaking and physical examination [12].
In diagnosing lobar pneumonia, an evidence-based approach to
physical examination asks, ‘What findings most accurately increase
the probability of pneumonia?’ by studying patients with respiratory
complaints and comparing their physical examinations to chest
radiographs. Based on evaluation of over 6000 patients, there are
six traditional physical findings that reliably predict the results of
the chest radiograph (see Figure 2.1). The remaining findings,
whether present or absent, add very little to the diagnosis of pneumonia. Using an evidence-based approach can trim the clinician’s
focus from 15 findings of unknown value to six findings with
proven value, thereby increasing confidence, efficiency, and accuracy. Clinicians applying this method can then approach their next
patient with cough and dyspnoea as if they had personally examined each of the 6000 patients in these studies and then recalled the
value of the physical examination gleaned from that experience.
The figure on the left of each box shows the percentage probability
at each age and by sex when the patient had no risk factors and the
number on the right-hand side of each box shows the percentage
probability of coronary heart disease in patients with the risk factors
diabetes, smoking, and hyperlipidaemia.
Reproduced with permission from Henderson MC, Tierney LM,
Smetana GW. The Patient History: An Evidence-based Approach to
Differential Diagnosis, 2 edn. New York: Lange/McGraw-Hill, 2012.
patients of different ages presenting with chest pain. The patients
all had normal 12-lead electrocardiograms and diagnosis was
based on history alone. Even without any risk factors, age alone
substantially increased the risk of coronary heart disease. The
presence of risk factors was particularly helpful in diagnosing
middle-aged patients. Women lagged men in the incidence of
coronary heart disease until menopause was reached.
TRADITIONAL FINDINGS
Fever
Tachypnea
Tachycardia
Reduced oxygen saturation
Grunting respirations
Cyanosis
Asymmetric chest excursion
Percussion dullness
Diminished breath sounds
Crackles
Egophony
Bronchophony
Whispering pectoriloquy
Bronchial breath sounds
Pleural rub
Figure 2.1 Diagnosis of lobar pneumonia. Textbooks present 15 traditional
physical findings of pneumonia (left), along with the assumption that each
finding has similar diagnostic weight. The evidence-based method (right),
based on study of actual patients, shows that five findings accurately
increase probability of pneumonia, and only one finding decreases it.
EVIDENCE-BASED APPROACH
5 findings increase probability
Asymmetrical chest excursion
Egophony
Bronchial breath sounds
Percussion dullness
Oxygen saturation <95%
1 finding
decreases probability
All vital signs normal
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