Clinical diagnosis of asthma

For assessment of children aged 1 to 5 years with respiratory symptoms suggestive of asthma, see Assessment of wheeze and asthma in children 5 years and younger.

The first step in assessing a child older than 6 years, an adolescent or an adult with suspected asthma is to take a detailed history and perform a physical examination to identify the pattern of symptoms and exclude other causes. The predictive value of a single sign or symptom is poor, but combinations of signs and symptoms can provide a clearer clinical picture to support a diagnosis of asthma.

Patient history should include:

current symptoms (wheeze, cough, shortness of breath, chest discomfort or tightness)
pattern of symptoms (frequency, time of day or night)
severity of symptoms (impact on work, school or lifestyle)
allergies (eg atopic dermatitis, allergic rhinitis)
aggravating or precipitating factors (eg exercise, viral infections)
smoking history (including exposure to second-hand smoke in the home) and exposure to biomass smoke (eg indoor fires for heating or cooking)
relieving factors (including medication trials)
presence of sinonasal disease
family history of allergies or asthma.

The physical examination should include:

chest auscultation
height and weight (for children)
inspection for chest deformity (for children)
assessment of respiratory rate and work of breathing (for children).

If atopy is suspected, inspect the upper respiratory tract for signs of allergic rhinitis (eg inflammation in the nasal passages) and the skin for signs of atopic dermatitis.

A chest X-ray is not necessary for diagnosis of asthma—it can be considered for unusual symptoms, or as required for suspected alternative diagnoses (eg lung cancer, pneumonia).

A summary of the key symptom patterns and features consistent with asthma, and those less consistent with asthma, are provided in Clinical features that increase and decrease the probability of asthma in children 6 years and older, adolescents and adults.

Alternative diagnoses to consider according to the predominant symptom are suggested in Alternative diagnoses that can be confused with asthma.

Table 1. Clinical features that increase and decrease the probability of asthma in children 6 years and older, adolescents and adults
CLINICAL FEATURES THAT INCREASE THE PROBABILITY OF ASTHMA
more than one of the following symptoms: wheeze, breathlessness, chest tightness or discomfort, cough—particularly if symptoms: are worse at night and in the early morning occur in response to exercise, allergen exposure or cold air occur after taking aspirin or beta blockers are recurrent history of atopic disorder (eg allergic rhinitis, atopic dermatitis) family history of asthma or atopic disorder widespread wheeze heard on auscultation of the chest improvement in symptoms or lung function in response to standard asthma therapy otherwise unexplained low FEV₁ or PEF (historical or serial readings) otherwise unexplained peripheral blood eosinophilia in children, presence of conditions associated with asthma (eg bronchopulmonary dysplasia, obstructive sleep apnoea, recurrent bronchiolitis)
CLINICAL FEATURES THAT LOWER THE PROBABILITY OF ASTHMA
chronic productive cough in the absence of wheeze or breathlessness normal FEV₁ when symptomatic [NB1] repeatedly normal auscultation of chest when symptomatic voice disturbance or throat tightness symptoms that worsen with talking or laughing prominent dizziness, light-headedness, peripheral tingling symptoms that only occur with viral respiratory infections, with few or no symptoms in between no response to a trial of asthma therapy significant smoking history (more than 20 pack years [NB2]) clinical features supporting an alternative diagnosis
Note: FEV₁ = forced expiratory volume in 1 second; PEF = peak expiratory flow NB1: Normal spirometry when the patient is not symptomatic does not exclude the diagnosis of asthma; ideally, repeat spirometry when the patient is symptomatic. If spirometry is normal when the patient is symptomatic, consider an alternative diagnosis. Repeated measurements of lung function are often more informative than a single assessment. NB2: Pack years is calculated using the formula (years of smoking × cigarettes per day) / 20; see here for an online calculator. A significant smoking history could indicate that the patient has chronic obstructive pulmonary disease (COPD). Asthma and COPD can coexist; see Overlap of asthma and COPD.

Table 2. Alternative diagnoses that can be confused with asthma
Predominant symptom	Possible alternative diagnoses in adults and adolescents [NB1]	Possible alternative diagnoses in children
breathlessness	lack of fitness obesity COPD hyperventilation or dysfunctional breathing anxiety inducible laryngeal obstruction (vocal cord dysfunction) heart failure pleural effusion pulmonary fibrosis lung cancer large airway stenosis congenital heart disease pulmonary hypertension inhaled foreign body pulmonary embolism tachyarrhythmias tracheobronchomalacia interstitial lung disease cystic fibrosis	inducible laryngeal obstruction (vocal cord dysfunction) anxiety inhaled foreign body congenital heart disease tracheobronchomalacia interstitial lung disease cystic fibrosis
wheeze	COPD bronchiectasis inducible laryngeal obstruction (vocal cord dysfunction) large airway stenosis tracheobronchomalacia inhaled foreign body heart failure	wheeze associated with viral respiratory infection transient infant wheeze tracheobronchomalacia airway lesion inhaled foreign body (unilateral wheeze) congenital heart disease
chest tightness	ischaemic heart disease hyperventilation or dysfunctional breathing oesophageal disorders (eg gastro-oesophageal reflux) anxiety	anxiety hyperventilation or dysfunctional breathing
dry cough	postinfective cough upper airway cough syndrome (postnasal drip) inducible laryngeal obstruction (vocal cord dysfunction) oesophageal disorders (eg gastro-oesophageal reflux) drug-induced (eg ACEI) COPD chronic rhinosinusitis lung cancer inhaled foreign body pulmonary fibrosis	postinfective cough (respiratory viruses, Bordetella pertussis or Mycoplasma pneumoniae) habit cough, particularly if it resolves during sleep inhaled foreign body
wet cough or sputum production	COPD chronic bronchitis bronchiectasis rhinitis lung cancer cystic fibrosis allergic bronchopulmonary aspergillosis	protracted bacterial bronchitis chronic suppurative lung disease (including bronchiectasis) cystic fibrosis inhaled foreign body
Note: ACEI = angiotensin converting enzyme inhibitor; COPD = chronic obstructive pulmonary disease NB1: Likelihood of alternative diagnoses depends on other patient-specific factors such as age, comorbid conditions, smoking history and other findings.