Asthma Differential Diagnosis

Differential Diagnosis

When symptoms are not typical with asthma and lung function does not support asthma, consider other diagnoses. Failure to respond to asthma treatment should prompt the search for an alternative or additional diagnosis. Asthma symptoms are nonspecific and are shared with other diseases such as the following:

• Aspiration
• Bronchiectasis
• Cardiac disease
• Vocal cord dysfunction
• Hyperventilation syndrome and panic attacks
• Interstitial lung disease
• Tumor: Laryngeal, lung, tracheal
• Cystic fibrosis
• Chronic obstructive pulmonary disease
• Foreign body
• Pulmonary embolism

Difficult Diagnostic Groups  

The following are the difficult diagnostic groups that may require specialist referral.  

In children ≤5 years old, episodic wheezing and coughing are common in children, especially ages <3 years. Diagnosis is based primarily on clinical judgment, evaluation of symptoms, and physical findings. There are symptoms that are highly suggestive of asthma such as recurrent wheezing, nocturnal cough not associated with a viral infection, a wheeze that does not vary seasonally, and the presence of symptoms after 3 years old. A trial of treatment with short-acting bronchodilators and inhaled glucocorticosteroids may help confirm the diagnosis in this age group.  

*Please see Asthma disease management chart in the latest edition of MIMS Pediatrics for further information.  

The elderly population may present with wheezing, breathlessness, and cough that are sometimes cardiac in etiology, hence, a thorough history and physical exam, together with an electrocardiogram (ECG) and chest X-ray may help distinguish a cardiac pathology.  

Chronic obstructive pulmonary disease should be differentiated from asthma by a trial of treatment with bronchodilators and/or inhaled glucocorticosteroids wherein marked improvement after bronchodilator or inhaled glucocorticoid suggests asthma.  

Occupational asthma is acquired in the workplace, usually caused by inhalant chemicals (eg isocyanates, platinum salts, complex plant, and animal biological products). Diagnosis is successfully confirmed with lung function measurement, particularly serial measurement of peak expiratory flow at work and away from work, and specific bronchial provocation testing. Seasonal asthma may occur intermittently with the patient being entirely asymptomatic between seasons or may occur as a seasonal worsening of symptoms in an asthmatic patient.  

Cough variant asthma has the principal symptom of chronic cough frequently during the night. Documentation of variability in lung function or of airway hyperresponsiveness and the search for sputum eosinophilia are important for possible diagnosis.  

Patients on Controller Treatment  

For patients currently taking controller treatments but have not been previously documented, confirming the diagnosis is based on the presence of variable respiratory symptoms with variable airflow limitation.  

For patients with variable respiratory symptoms without variable airflow limitation, the bronchodilator reversibility test should be repeated after withholding bronchodilator treatments. This may indicate that controller treatment may need to be reassessed.  

For patients with few respiratory symptoms, with no variable airflow limitation, and normal lung function, withholding the bronchodilator treatment before repeating the bronchodilator reversibility test should be done. If the patient develops symptoms and the lung function worsens after the withdrawal of treatments, the diagnosis is confirmed. If there is an absence of symptoms and lung function remains the same after withdrawal of treatment, cessation of controller treatments may be done.  

The presence of dyspnea with fixed airflow limitation may indicate the need to reassess the treatment regimen and further management.