Differentials
| System |
What might it be? |
What might I find? |
|
| Respiratory |
Asthma |
RF: personal/family hx atopy e.g., eczema, hay fever, food allergies.
Typical presentation in childhood. Episodic symptoms with diurnal variation. Shortness of breath, cough, wheeze, chest tightness. Improve w/bronchodilators. Widespread, polyphonic wheeze found on auscultation of the chest. |
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|
Chronic Obstructive Pulmonary Disease |
RF: long-term smoking history, increased age.
Persistent breathlessness, cough, wheeze, sputum production, recurrent LRTI. Minimally reversible with bronchodilators. Diagnosed by spirometry – obstructive. Chest x-ray usually shows hyper-inflated lung fields & rules out differential dx. |
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|
Bronchiectasis |
RF: airway damage – pneumonia, TB, CF, a1-antitrypsin deficiency, idiopathic.
Chronic productive cough, breathlessness, recurrent LRTI, weight loss. OE: finger clubbing, scattered crackles which clear on coughing, wheeze. May develop cor pulmonale signs – raised JVP, peripheral oedema. CXR: Tram-track opacities and ring shadows due to dilated airways. |
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Viral Infection |
Infection and inflammation of respiratory tract caused by a virus e.g., rhinovirus.
Affect pharynx, larynx, trachea and bronchi. Self-limiting condition. Cough associated with nasal congestion, sore throat, pyrexia, headache. |
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Pneumonia |
Acute illness with cough, fever, breathlessness, pleuritic chest pain.
Cough generally productive of purulent sputum. May be unwell, fever, tachycardia, confusion – increased risk in vulnerable patients e.g., elderly. |
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Post-nasal Drip |
RF: rhinitis, older age, GORD, medications thickening mucus e.g., diuretics.
Increased mucus production by nasal mucosa drips into upper airway causing irritation, cough, throat clearing, hoarseness, sensation of a lump in the throat. Also referred to as upper airway cough syndrome. |
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Lung Cancer |
RF: older age, smoking.
Cough, haemoptysis, shortness of breath, weight loss, recurrent pneumonia. Finger clubbing and lymphadenopathy (often supraclavicular) on examination. Multiple extra-pulmonary manifestations, e.g., SIADH, hypercalcaemia, etc. |
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Pulmonary Embolism |
RF: immobility, recent surgery, pregnancy, long-haul travel, oestrogen-containing hormone therapy, cancer, obesity, smoking, thrombophilia, previous DVT or PE.
Acute shortness of breath, pleuritic chest pain, haemoptysis, DVT signs. Tachypnoea, ↑HR, hypoxia, hypotension (if significant haemodynamic instability). |
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| Cardiovascular |
Chronic Heart Failure |
RF: Underlying AF, valve disease, IHD, HTN, cardiomyopathy.
SOB on exertion, orthopnoea, PND, peripheral oedema, fatigue. Raised JVP, bibasal crackles, heart murmur. Cough w/ frothy white/pink sputum. |
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| Miscellaneous |
Gastro-oesophageal Reflux Disease |
RF: obesity, smoking, hiatus hernia, alcohol, coffee, NSAIDs, spicy food.
Heartburn, bloating, cough, voice changes, acidic taste in the mouth. |
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|
Pharmacological |
ACE-inhibitors, beta blockers, NSAIDs, calcium channel blockers. | ||
Checklist
| Preparation | Wash – Name – Explain | |
| Presenting Complaint | Open question to establish reason for presentation | |
| Allow patient time to talk uninterrupted | ||
| History of Presenting Complaint | Onset | |
| Frequency | ||
| Character | ||
| Timing | ||
| Exacerbating/relieving factors | ||
| Associated symptoms | ||
| Previous similar episodes | ||
| System-specific | Shortness of breath | |
| Wheeze | ||
| Chest pain | ||
| Fever | ||
| Red Flags |
Rule in/out serious disease |
|
| Relevant Systems Review | Gastrointestinal | |
| Ear, Nose & Throat | ||
| ICE | What do you think is going on? | |
| Is there anything that is worrying you? | ||
| What were you hoping we would do today? | ||
| Past Medical History | Past medical history | |
| Past surgical history | ||
| Drug History | Prescribed medication | |
| Over-the-counter medication | ||
| Drug allergies | ||
| Social History | Smoking | |
| Alcohol | ||
| Recreational drugs | ||
| Work | ||
| Driving | ||
| Who is at home? | ||
| Condition of accommodation | ||
| Pets | ||
| Dust and allergen exposure | ||
| Sick contacts | ||
| Forgeign travel | ||
| Family History | Does anyone in the family have respiratory disease? | |
| Do any other health conditions run in the family? | ||
| Comm. Skills | Establish rapport | |
| Use open and closed questions appropriately | ||
| Structured history taking | ||
| Pick up on cues | ||
| Rule in/out differential diagnoses | ||
| Summarise succinctly |
Explanation
Preparation
Wash, name, explain:
- Wash your hands
- Introduce yourself by name and role
- Check the patient’s name and date of birth
- Explain the task and get consent
“I’ve been asked to speak to you about the cough you’ve been experiencing. I will ask you some questions to help determine what might be causing it. Does that sound all right?”
Presenting Complaint
Begin with an open question to establish the patient’s reason for presentation, for example, “Could you tell me about what’s been going on?”
Try to let the patient speak for 30-60 seconds without interruption. This is referred to as the ‘golden minute’ and can provide valuable information about why the patient has sought medical attention, as well as cues surrounding their ideas, concerns, and expectations (ICE) to explore later in the consultation.
History of Presenting Complaint
Next, you need to gather more specific information about the patient’s presenting complaint to establish the differential diagnosis. You can use a mixture of open and closed questions.
An example of an open question here would be: “Can you tell me more about this cough?” or “Have you noticed any other symptoms alongside the cough?” Examples of closed questions include: “Have you coughed up any blood?” or “Is the cough worse at night?”
When taking a cough history, you may find it useful to use a structured approach to your questioning. For example:
- Onset – when did the cough start? Is the cough acute (viral respiratory tract infection, pneumonia, bronchitis, or exacerbation of stable lung disease, e.g., asthma, bronchiectasis, or COPD) or chronic (COPD, asthma, upper airway cough syndrome, GORD)?
- Frequency – how often is the patient coughing? Is there any pattern to episodes of symptoms? Has the frequency changed over time?
- Character – is the cough dry or productive? If productive, what is the colour and consistency of the sputum? E.g., clear, purulent, white, frothy, or blood-stained.
- Timing – What time of day does the cough occur? Any associated triggers? Has the timing of episodes changed since the patient first noticed their symptoms? Diurnal variation (fluctuation of symptoms according to the time of day) is a common feature of asthma and is useful in the diagnostic process, whereas GORD may present with cough which is worse after food. Did the cough start shortly after starting a new medication, e.g., an ACE inhibitor?
- Exacerbating and relieving factors – does anything bring on the cough? Does anything make it better? Common asthma triggers include cold, exercise, allergen exposure, infection, and strong emotion; relief is often provided by inhaled bronchodilators.
- Associated symptoms – does the patient experience any other symptoms alongside the cough? Acute cough associated with coryzal symptoms is likely to be caused by viral respiratory infection, whereas cough with weight loss, fatigue, and finger clubbing would make you concerned for more serious pathology, e.g., malignancy, pulmonary fibrosis or bronchiectasis.
- Previous similar episodes – has this ever happened to the patient before? Did it feel the same or different? Was there a common trigger? Symptom diaries can be useful to identify patterns in symptom episodes.
System-specific History
After establishing further information about the cough, you need to gather any relevant system-specific information. In this case, the system in question is the respiratory system. Try to think of symptoms that may occur alongside cough and ask about these.
It is important not only to ask these questions, but also to understand how the patient’s answers help narrow down the differential diagnosis.
Respiratory system-specific questions to ask include, but are not limited to:
- Shortness of breath – shortness of breath differentials associated with a dry cough include asthma and pulmonary fibrosis. Breathlessness with a productive cough is a feature of COPD, bronchiectasis, pneumonia (purulent sputum), and chronic heart failure (frothy white/pink sputum).
- Wheeze – cough with wheeze is found in asthma and COPD secondary to bronchospasm. Chronic heart failure can cause a cough and ‘cardiac wheeze’ secondary to fluid in the lung fields (pulmonary oedema).
- Chest pain – cough may cause musculoskeletal chest pain due to repeated chest wall strain. Infective causes of cough can cause pleurisy and thus pain on coughing or inspiration. Bronchospasm in asthma or COPD may cause chest tightness that is described as pain or discomfort. Pleuritic chest pain and haemoptysis are concerning for pulmonary embolism.
- Fever – pyrexia associated with cough indicates an infective cause, e.g., pneumonia, TB, viral respiratory tract infection.
Red Flags
Features in a cough history that are concerning for serious pathology and should trigger an urgent referral for further assessment include:
- Haemoptysis – may indicate lung malignancy or pulmonary embolism.
- Weight loss is a red flag for malignancy and should be urgently investigated.
- Dysphagia is a red flag and needs urgent assessment. Assess if the dysphagia is above the sternal notch, e.g., in the throat requiring an urgent referral to ENT, or lower dysphagia requiring urgent referral on an upper gastro-intestinal pathway.
Relevant Systems Review
A systems review is a useful tool to ensure no important information from the history has been missed. However, it is key to consider which systems to review to keep your questions relevant to the presenting complaint.
Appropriate systems to review when taking a cough history include:
- Cardiovascular – symptoms which may lead you to consider heart failure as a cause of cough include peripheral oedema, orthopnoea, paroxysmal nocturnal dyspnoea, and the need for increased numbers of pillows to sleep at night.
- Gastrointestinal – GORD is a common cause of chronic cough, so ask about heartburn, belching, acidic taste in the mouth, bloating, and voice changes.
- Ear, Nose & Throat – coryzal symptoms, e.g., sore throat and nasal congestion with cough may indicate viral respiratory tract infection. Excess nasal mucus, throat irritation, throat clearing, hoarseness, and sensation of a lump in the throat may indicate a diagnosis of upper airway cough syndrome (post-nasal drip).
Ideas, Concerns & Expectations (ICE)
Using the ICE mnemonic, you can gather information about how the patient feels about their symptoms, whether they have any specific worries or concerns, and how they hope to move forward after seeking medical attention.
Try to find your own approach to asking about ICE that suits your personal style. Some examples are included below:
- Ideas – “Do you have any thoughts about what might be going on?” “What do you think might be causing this cough?”
- Concerns – “Is there anything that is worrying you about this cough?” “Have you read or Googled anything about your symptoms that has caused you concern?”
- Expectations – “Was there anything specific you were hoping we would do today?” “Do you have any ideas about what might happen next?”
Past Medical History
Gather information about previous or existing health conditions that the patient may have. Try to note when an existing condition may be of significance in the context of a presenting complaint of shortness of breath. For example, a patient with a history of atopic conditions including eczema and hay fever is more likely to develop asthma.
Ask about previous surgery or procedures the patient may have undergone.
Drug History
Ask the patient about any regular medication they take, not forgetting to ask specifically about medications that the patient may not think to volunteer, e.g., over-the-counter medications, herbal or alternative remedies, contraception, HRT, or injections such as vitamin B12.
Try to think about whether the information you are given could be relevant to the differential diagnosis. A patient with a cough who has just been started on an ACE inhibitor, e.g., ramipril for hypertension may be experiencing a drug side effect.
Check whether the patient is compliant with their medication and taking it as prescribed. Pay particular attention to patients presenting with worsening breathlessness who are prescribed inhalers for asthma or COPD. Do they have a correct understanding of how and when to take each inhaler? Are they using a spacer? Check their inhaler technique.
Remember to ask about drug allergies and clarify any reported symptoms to differentiate a true allergy from an intolerance.
Social History
This is the chance to learn more about the patient, beyond their presenting complaint.
- Who do they live with? Do they have a social support network, e.g., if receiving a debilitating diagnosis. Would someone else be at home to witness a symptom episode or to call for help if required?
- What is the condition of their accommodation? Dusty, smoky, or damp accommodation may exacerbate underlying respiratory conditions, e.g., asthma.
- Do they have any pets? Pet dander may be an allergen and asthma trigger. Keeping certain birds can be associated with interstitial lung disease, though this is rare.
- Is there any significant dust or allergen exposure? Exposure to certain dusts can trigger or worsen respiratory disease. Exposure may be occupational, e.g., construction, textile, mining, and forestry, or through hobbies, e.g., DIY, woodwork, metalwork, and gardening.
- Do they work? Are they able to work with their current symptoms, and is it safe to continue working while their symptoms are being investigated? Is there a history of asbestos exposure at work? If so, and the patient develops asbestos-related disease, they may be entitled to compensation.
- Do they drive? Does their condition affect their ability to drive or attend appointments?
- Have they had contact with someone with similar symptoms? Infective differentials, e.g., viral infections, pneumonia, TB, may be traceable via a contact history.
- Have they recently returned from travelling abroad? Consider mechanisms of respiratory pathogen spread, e.g., air travel, air-conditioning (legionella).
- Do they smoke? Smoking is well known to cause and exacerbate respiratory conditions including COPD, lung cancer, and asthma. Don’t forget to ask about passive smoking, or smokers in the household.
- Do they drink alcohol?
- Do they use recreational drugs? Some recreational drugs are inhaled, e.g., cannabis, cocaine, nitrous oxide.
Family History
Does anyone in the family have respiratory or cardiovascular disease? For example, a family history of atopy (asthma, eczema, hay fever) is a risk factor for a patient developing asthma.
Finishing
Thank the patient and wash your hands. Consider your differential diagnosis and how you might narrow this down further through examination, bedside tests, or further investigation/imaging.
Last updated April 2025
Head to members.zerotofinals.com for practice OSCE stations, including an interactive checklist, specific cases and clinical findings.
