Adults

- History
- Examination
- Tests
- Red Flags

History

Taking a thorough history is an integral part of diagnosing asthma; 90% of the diagnosis is based on the patient history.

Asthma is a syndrome with a collection of symptoms. The assessment should record the nature, duration, frequency and severity of symptoms. It should also seek to identify triggers (i.e. aggravating and precipitating factors), associated diseases, family history and the patient's occupation.

Questions should ascertain:

Any family history of atopy- eczema, hay fever or asthma
Presence of comorbid atopic condition
Pattern and time of symptoms, e.g. night / early morning, variation in symptoms day-to-day, nocturnal symptoms
Symptom triggers
Age of onset

Completion of the short Adult asthma diagnosis questionnaire(approximately 1 minute completion time) will indicate the likelihood of asthma diagnosis based on a patient’s reported symptoms. Further clinical investigation is suggested for those patients whose questionnaire responses are highly suggestive of asthma.(Not all tests may be available within the scope of general practice)

Examination

A physical examination should aim to ascertain the presence or absence of:

Expiratory wheeze on auscultation.
Increased expiratory time
Hyperinflation

Tests

Overview

Clinical features that increase the probability of asthma
More than one of the following symptoms: wheeze, cough,rhinitis, difficulty breathing, chest tightness, particularly if: Symptoms are worse at night and in the early morning Symptoms in response to exercise, allergen exposure and cold air Symptoms after taking aspirin or betablockers Personal history of atopic disorder Family history of atopic disorder and/or asthma Widespread wheeze heard on auscultation of the chest Otherwise unexplained lower FEV₁ or PEFR (historical or serial readings) Otherwise unexplained peripheral blood eosinophilia Raised sputum eosinophil count (specialist centres only) Raised exhaled nitric oxide measurement (fENO)
Clinical features that lower the probability of asthma
Prominent dizziness, light-headedness, peripheral tingling Chronic productive cough in the absence of wheeze or breathlessness Repeatedly normal physical examination of chest when symptomatic Voice disturbance Symptoms with colds only Significant smoking history, i.e. >20-pack years Cardiac disease Normal PEFR or spirometry when symptomatic*

*normal spirometry when not symptomatic does not exclude the diagnosis of asthma. Repeated measurements of lung function are often more informative than a single assessment.

Adapted from British Thoracic Society (BTS) Scottish Intercollegiate Guidelines Network (SIGN) 101. British Guideline on the Management of Asthma: a national clinical guideline. 2009.

Available from http://www.sign.ac.uk/guidelines/fulltext/101/index.html

Lung function tests

Diagnostic tool	Findings that support diagnosis
Reversibility testing with spirometry or PEFR	Demonstration of reversible airflow limitation: FEV₁ improves at least 12% and 200 ml either spontaneously, after inhaled bronchodilator, or after trial of corticosteroid therapy; OR PEFR improves at least 15% after inhaled bronchodilator or after trial of corticosteroid therapy. (Note: Postbronchodilator FEV₁/FVC < 0.70 suggests COPD.)
Exercise challenge with spirometry or PEFR	Demonstration of airway hyper-responsiveness: FEV₁ decreases at least 15% from baseline after 6 minutes of exercise; OR PEFR decreases at least 20% from baseline after 6 minutes of exercise.
Home PEFR diary (if needed)	Demonstration of variable airflow limitation: PEFR varies more than 20% from morning measurement upon arising to measurement 12 hours later in patients taking a bronchodilator (more than 10% in patients not taking a bronchodilator).

Adapted from Global Initiative for Asthma (GINA). Pocket Guide for Asthma Management and Prevention in Children. 2004. Available from http://www.ginasthma.org.

Allergy skin testing

Skin-prick testing is used to confirm reaction to an allergen. A drop of liquid containing the allergen is placed on the skin (usually 15-30 concurrent tests for the most common allergens), then the skin is pierced with a lancet. If the individual is hypersensitive a hive will form within 2 minutes.

IgE testing (radioallergosorbent test/IgE specific immunoassay –RAST testing)

Specific IgE testing is helpful where skin-prick testing cannot be performed, e.g. presence of eczema. The blood test measures the amount of IgE antibody in the blood for the suspected allergen(s) and is very specific.

Chest X-Ray (CXR)

Chest x-rays are not normally indicated in the normal assessment of suspected asthma and should only be considered if clinical signs indicate another condition e.g. carcinoma, pneumothorax, foreign bodies.

Therapeutic trial

When clinical judgement indicates a high probability of asthma, but reversibility is not demonstrated on spirometry, a therapeutic trial with inhaled corticosteroid therapy (200-400mcg beclomethasone equivalent, daily) may be useful to confirm a diagnosis. The patient's symptoms should be monitored for improvement for 6-8 weeks. If symptoms recur on stopping therapy a diagnosis of asthma can be established.

Red Flags and differential diagnoses

When a patient remains symptomatic despite optimal prescribed treatment and confirmation of effective inhaler technique and good compliance, then referral to secondary care or specialist respiratory services should be considered.

The list below is not exhaustive.

Differential diagnoses

Differential diagnosis of asthma in adults, according to the presence or absence of airflow obstruction (FEV₁/FVC<0.7)
Chronic cough syndromes
Hyperventilation syndrome
Vocal cord dysfunction
Rhinitis
Gastro-oesophageal reflux
Heart failure
Pulmonary fibrosis
With airflow obstruction
COPD
Bronchiectasis*
Inhaled foreign body*
Obliterative bronchiolitis
Large airway stenosis
Lung cancer*
Sarcoidosis

*May also be associated with non-obstructive spirometry

Indications for specialist referral in adults
Diagnosis unclear
Unexpected clinical findings (i.e. crackles, clubbing, cyanosis, cardiac disease)
Unexplained restrictive spirometry
Suspected occupational asthma
Persistent non-variable breathlessness
Monophonic wheeze or stridor
Prominent systemic features (myalgia, fever, weight loss)
Chronic sputum production
CXR shadowing
Marked blood eosinophilia (>1 x 10⁹/L)
Poor response to asthma treatment
Severe asthma exacerbation

Adapted from British Thoracic Society (BTS) Scottish Intercollegiate Guidelines Network (SIGN) 101. British Guideline on the Management of Asthma: a national clinical guideline. 2009. Available at http://www.sign.ac.uk/guidelines/fulltext/101/index.html

Completion of the short Differential diagnosis questionnaire (approximately 1 minute completion time) will help evaluate the possibility of asthma and COPD in adult patients over the age of 40 years who have never smoked OR have a prior diagnosis of respiratory disease or current regular respiratory treatment. It will not produce a definitive diagnosis, but may help determine whether a diagnosis of asthma or COPD is more likely in an individual patient; the more likely diagnosis can then be investigated further.