Diagnosing asthma in adults

The information in this section will help you to understand the fundamentals of diagnosing asthma in primary care.

This is not a substitute for completing an appropriate respiratory assessment module.  For advice and support on choosing the right course for you, please see our training and development page.

 

What is asthma?

Asthma is a chronic respiratory condition associated with airway inflammation and hyper-responsiveness.

7.2 million people in the UK are living with asthma.

Symptoms include cough, wheeze, chest tightness, and shortness of breath.

Symptoms are variable - they can come and go.  

Symptoms can be triggered by many factors such as exercise, allergen or irritant exposure, changes in weather, and viral respiratory infections.

Symptoms may go by themselves or in response to medication, and may sometimes be absent for weeks or months at a time. 

Studies estimate that approximately 30% of people with a diagnosis of asthma may not have asthma. 

Watch this video to understand more - and for some tips on how to explain asthma to your patients.

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Asthma affects the airways that carry air in and out of your lungs.
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This is what the inside of a healthy airway looks like.
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The muscles are relaxed and the airway is open so it’s easy to breathe.
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If you have asthma, your airways are more sensitive.
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When you come into contact with one of your asthma triggers,
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your airways get narrow and tight.
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The inside of your airways gets swollen and inflamed.
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If your airways are already inflamed, the inflammation will be worse.
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Some people also get sticky mucus or phlegm which makes the airways even more narrow.
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These changes in the airways make it much harder to breathe.
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You might get asthma symptoms
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like chest tightness, wheezing,
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coughing or feeling breathless.
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Use your reliever inhaler when you feel symptoms coming on.
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It opens the airways, making it easier to breathe.
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Remember though that your reliever inhaler,
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which is usually blue,
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cannot treat the inflammation
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in your airways,
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so it's very important to use your preventer inhaler.
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If you take your preventer inhaler everyday, as prescribed,
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it keeps down the inflammation in your airways
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so they're less sensitive
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and less likely to react to triggers.

Diagnosing asthma in adults

The diagnosis of asthma is like a jigsaw. 

You need to fit all the pieces together to see the complete picture. It is important to remember that in asthma the symptoms, clinical examination findings and test results can vary over time and sometimes it’s necessary to re-examine patients and repeat tests when they have their symptoms.  

There is no single diagnostic test for asthma. Diagnosis is based on a structured clinical assessment supported by objective tests that show variable airflow obstruction or airway inflammation.

Clinical assessment

Your first step should be to take a detailed clinical assessment.  This will help you determine if your patient has a high, intermediate or low likelihood of asthma.  

Questions to ask your patient

Why this question matters
Do you get a cough that comes and goes? Asthma is a variable condition, with cough as a common symptom.  A cough that is continuous is less likely to be asthma.
Do you get a tight feeling in your chest that makes it hard to breathe? Chest tightness is a symptom of asthma and can be caused by untreated inflammation in the airways.
Do you get out of breath? What are you doing when this happens? How long does it last? Breathlessness can be normal, especially during exercise, but is also a symptom of asthma.  Understanding when your patient becomes breathless can help identify asthma triggers.
Is your chest or your breathing ever noisy? What does it sound like? Avoid using the term 'wheeze' as this will be different for each person.  Instead, ask them to describe any chest sounds or record them on their phone if they can.
Do you ever wake up in the night, or early in the morning with chest symptoms? Night time or early morning symptoms are a sign of uncontrolled asthma. 
Are there triggers for your chest symptoms? For example, allergens, exercise, pets, cold air, viral infections? Symptoms in response to specific triggers make an asthma diagnosis more likely.
Can you breathe through your nose? Is it sometimes blocked or runny (rhinitis)?

Breathing through the nose filters and humidifies air. Mouth breathing can trigger asthma symptoms as cold air or other allergens are breathed in. 

Rhinitis can be caused by allergies.  
Do you get hayfever or eczema? Did you have either of these in childhood? People with allergies or eczema are more likely to have asthma
Did you have asthma as a child? Does anyone else in the family have asthma?   Childhood symptoms may not have been recorded as asthma but they may have been labelled as 'wheezy bronchitis'  described as a 'chesty child' and these could suggest previous undiagnosed asthma symptoms.
Do you have any other health problems such as lung cancer, COPD, post nasal drip, gastric reflux or anxiety?   All of these conditions can cause asthma like symptoms and happen in people with or without asthma.

 

Most NHS IT systems allow you to make searches of your patient’s notes. This is quick and easy to do and can help you find information you can use to decide if someone is more or less likely to have asthma.  Look for:

  • Previous chest symptoms, including any chest infections
  • A record of an HCP hearing a wheeze.

Look in the medications list.  Has your patient ever been prescribed any

  • Inhalers
  • Oral steroids  
  • Antibiotics for chest symptoms?

Have they ever had a raised blood eosinophil count? Having a raised blood eosinophil count can be a useful marker for asthma. However, there are other causes of raised eosinophils in the blood.

Chest auscultation

You should only listen to your patient’s chest if you are trained to do so.  If your patient is symptomatic, you may hear an expiratory polyphonic (multiple pitches and tones on the out breath) wheeze over different areas of the lung.  Remember, not all people with asthma wheeze.

Watch this video to hear lung sounds associated with asthma.  

Safety note: this video is for information only and does not constitute training

Absence of wheeze does not rule out asthma as a diagnosis.  This is because asthma is a variable condition, and your patient might not be symptomatic when you examine them.  

Having completed and documented your clinical assessment, you can use the diagnostic flowcharts in any of the following guidelines to help you work out if your patient has a high, intermediate or low probability of asthma.

Testing and trial of treatment

High probability  

If your patient has a high probability of asthma, record them as likely to have asthma and code as suspected asthma.  

If your patient is having symptoms,  start them on a 6-8 week trial of treatment immediately 

All patients with suspected asthma should have objective testing including 

  • Spirometry with reversibility 
  • Peak flow diary monitoring to record evidence of variable airflow obstruction.
  • FeNO (if available).

Ideally you would perform spirometry and FeNO testing before starting a trial of treatment, while your patient is symptomatic. It's important not to delay treatment though, so if you cannot test immediately then you can start a peak flow diary and bring your patient back for spirometry and FeNO (if available) on another date.

  • Assess and record your patient’s baseline status using a validated questionnaire such as the Asthma Control Test
  • Arrange a follow up appointment for 6-8 weeks time and repeat the same validated questionnaire to assess how their symptoms have responded  
  • Review their peak flow diary and calculate the diurnal variability
  • If your patient’s response to their trial of treatment is response is good and you have completed Spirometry and FeNO (if available), you can now confirm their diagnosis and code as asthma  
  • Complete a personalised asthma action plan (PAAP) with your patient.  Save it to your patient’s notes and give them a copy.  

Intermediate probability  

If your patient has an intermediate probability of asthma, they will need

  • Spirometry with reversibility  
  • Peak flow monitoring to demonstrate variabile airway obstruction
  • FeNO testing if available 
  • Blood eosinophil testing.

If the results show airway obstruction and your patient has symptoms, you can start treatment and review as per a high probability patient.  

Low probability  

If there is a low probability of asthma or you think an an alternative diagnosis is more likely, you need to investigate for the alternative diagnosis.  This can be complicated so if you are unsure, speak with a senior colleague for advice, or refer back to your patient’s usual GP.  

Reconsider asthma if the clinical picture changes or an alternative diagnosis is not confirmed.

 

 

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