From the Guidelines
Asthma diagnosis should be established through a combination of clinical evaluation, medical history, physical examination, and lung function tests, with spirometry being the primary diagnostic tool, as recommended by the expert panel report 3 (epr-3) guidelines 1. The diagnosis of asthma involves determining that episodic symptoms of airflow obstruction or airway hyperresponsiveness are present, airflow obstruction is at least partially reversible, and alternative diagnoses are excluded 1.
Key Diagnostic Criteria
- Episodic symptoms of airflow obstruction or airway hyperresponsiveness
- Airflow obstruction is at least partially reversible, measured by spirometry, with an increase in FEV1 of >200 mL and 12% from baseline measure after inhalation of short-acting b2-agonist (SABA) 1
- History of symptoms such as cough, recurrent wheeze, recurrent difficulty in breathing, and recurrent chest tightness
- Symptoms occur or worsen in the presence of specific triggers, such as exercise, viral infection, inhalant allergens, irritants, changes in weather, strong emotional expression, stress, menstrual cycles, and at night 1
Diagnostic Tools
- Spirometry: the primary diagnostic tool, which measures how much and how quickly air can be exhaled after taking a deep breath 1
- Physical examination: may reveal findings that increase the probability of asthma, but the absence of these findings does not rule out asthma 1
- Medical history: a detailed medical history is essential in making the diagnosis, including questions about symptom patterns, precipitating factors, and family history of asthma, allergy, or other atopic disorders 1
Additional Tests
- Peak flow monitoring: may be used to monitor asthma control, but is not a diagnostic tool 1
- Bronchoprovocation tests: such as methacholine challenge, may be used to assess airway hyperresponsiveness 1
- FeNO (fractional exhaled nitric oxide) measurement: may be used to detect airway inflammation 1
- Allergy testing: may be used to identify allergic triggers 1
- Chest X-rays: may be ordered to rule out other conditions, but are not diagnostic for asthma 1
From the Research
Asthma Diagnosis
- Asthma is a chronic disease characterized by inflammation and bronchoconstriction, and its diagnosis is based on the combined presence of typical symptoms and objective tests of lung function 2.
- The diagnosis of asthma is made through a combination of clinical assessment and diagnostic testing, including symptoms such as cough, dyspnea, and wheezing, as well as physical exam findings like hyperinflation, wheezing, and increased work of breathing 3.
- Objective diagnostic testing consists of two components: demonstration of airway obstruction and documentation of variability in degree of obstruction, which can be assessed through spirometry with bronchodilator reversibility testing, peak flow measurement, and bronchial challenge testing 2.
Diagnostic Testing
- Spirometry with bronchodilator reversibility testing remains the mainstay of asthma diagnostic testing for children and adults, and repetition of the test over several time points may be necessary to confirm airway obstruction and variability 2.
- Repeated peak flow measurement is relatively simple to implement in a clinical and home setting, while bronchial challenge testing is reserved for patients in whom the aforementioned testing has been unrevealing but clinical suspicion remains 2.
- Demonstration of eosinophilic inflammation, via fractional exhaled nitric oxide measurement, or atopy, may be supportive of atopic asthma, though diagnostic utility is limited particularly in nonatopic asthma 2.
Clinical Assessment
- Patients with asthma present with varied symptomatology and exam findings, and the 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 3.
- The diagnosis of asthma in the pediatric population may be more difficult because the classic symptoms may not be present in many of those patients, and the astute physician will rely on all three factors - clinical history, physical exam, and diagnostic testing - when making the diagnosis 3.
- Symptoms such as wheezing, chest tightness, and difficulty in taking a deep breath suggest asthma, while symptoms such as gasping, smothering, or air hunger suggest alternative diagnoses, and objective measures of lung function are necessary for the accurate diagnosis of asthma 4.