From the Guidelines
Diagnosing asthma relies on several key features, including clinical symptoms, lung function testing, and response to treatment, with the most recent and highest quality study 1 emphasizing the importance of episodic symptoms of airflow obstruction or airway hyperresponsiveness, partially reversible airflow obstruction, and a detailed medical history. The key features of diagnosing asthma include:
- Episodic symptoms of airflow obstruction or airway hyperresponsiveness, such as cough, wheeze, difficulty in breathing, or chest tightness, which occur or worsen in the presence of specific triggers like exercise, viral infection, or inhalant allergens 1
- Airflow obstruction that is at least partially reversible, measured by spirometry, with an increase in FEV1 of >200 mL and 12% from baseline measure after inhalation of a short-acting beta-2 agonist (SABA) 1
- A detailed medical history, including questions about the overall pattern of symptoms, precipitating factors, and a family history of asthma, allergy, or other atopic disorders 1
- Physical examination findings, such as wheezing, hyperexpansion of the thorax, or atopic dermatitis, although the absence of these findings does not rule out asthma 1
- Spirometry, which is an essential objective measure to establish the diagnosis of asthma, particularly in patients aged 5 years or older, as it can demonstrate obstruction and assess reversibility 1 The diagnosis of asthma should also consider alternative diagnoses, and additional studies, such as chest radiography or specific blood tests, may be necessary to exclude other potential causes of symptoms 1.
From the Research
Key Features of Diagnosing Asthma
- Diagnosis of asthma is based on the combined presence of typical symptoms and objective tests of lung function 2
- Objective diagnostic testing consists of two components:
- Demonstration of airway obstruction
- Documentation of variability in degree of obstruction 2
- Symptoms of asthma include episodic breathlessness, wheeze, cough, tightness of the chest, and shortness of breath 3, 4
- Physical exam can demonstrate hyperinflation, wheezing, and increased work of breathing, but most patients will present with a normal pulmonary exam because they are between episodes 4
- Diagnostic testing for asthma includes:
- Spirometry with bronchodilator reversibility testing, which remains the mainstay of asthma diagnostic testing for children and adults 2, 5
- Repeated peak flow measurement, which is relatively simple to implement in a clinical and home setting 2
- Bronchial challenge testing, which is reserved for patients in whom the aforementioned testing has been unrevealing but clinical suspicion remains 2
- Fractional exhaled nitric oxide measurement, which may be supportive of atopic asthma 2
Diagnostic Approach
- A compound diagnostic approach and label is required for asthma diagnosis, which includes eliciting typical symptoms and abnormal physiology of variable airflow limitation 6
- Identification of further features, such as eosinophilic or type 2 inflammation, allows a compound diagnostic label of eosinophilic asthma 6
- Treatable traits are a useful way to implement this new approach to diagnosis, which involves targeted assessment to inform a specific treatment plan in a pragmatic and iterative process 6