Approximately 10% of the adult asthma population have severe asthma, which if uncontrolled is associated with substantial physical and mental consequences as well as airway remodelling leading to an estimated 32- fold risk of chronic obstructive pulmonary disease.
Direct systematic questioning is essential at every interaction. Many patients do not fully understand how to gauge asthma control, may forget past events or self-impose activity limitations. Probing for specifics about exacerbation episodes, exacerbation risks and symptom control provides a more complete picture of the patient’s level of control.
In well-controlled asthma there are daytime symptoms no more than twice per week, night-time symptoms no more than twice per month, SABAs for relief of symptoms needed less than three days a week (not including usage prior to exercise), no interference with normal activity and peak flow should remain normal or near normal.
Quick, validated questionnaires addressing these measures include the ACT (Asthma Control Test), and Asthma Control Questionnaire (ACT). Exacerbation risk assessment should be considered with the most important risk being an exacerbation in the preceding year. Adherence to preventers and smoking are additional important risks.
Ongoing airway inflammation is a hallmark of asthma, even in patients with occasional symptoms. Patients who may not recognise or report symptoms until airflow has become severely obstructed. Pulmonary function testing or spirometry is therefore essential.
Defining severe asthma
The frequency of symptoms and exacerbations are considered elements of asthma control. Disease severity is defined by the medication type and dosage a patient requires to maintain adequate control .
Severe asthma in adults is generally taken as asthma needing treatment with medium- high dose inhaled corticosteroids (ICS) and one or more additional controller mediation (e.g., LABA) or systemic corticosteroids for at least half the previous year and asthma remaining uncontrolled despite this therapy.
‘Uncontrolled’ requires the presence of at least one of the following: poor symptom control, frequent or a serious exacerbation, or airflow limitation. Accurate asthma diagnosis and exclusion of other possible conditions with similar symptoms is important with studies showing up to 40% of referred patients may not have asthma.
Severity can be determined by the treatment the patient is receiving and how well that treatment is managing the asthma. For instance, a patient receiving high-dose ICS and two other controller medications continuing to experience exacerbations and/or require oral corticosteroid bursts has severe asthma
Severe asthma patients result in 60% of overall treatment costs of all asthmatics and have high morbidity and mortality. They are commonly encountered in primary care. Recognition is critical to facilitate early intervention and collaboration with a specialist with advent of new, targeted therapy such as omalizumab (ani-IgE) and mepolizumab (anti-IL5) that can significantly improve patient outcomes.
- Asthma severity and control are distinct issues
- Accurate diagnosis and assessment are critical
- New biological agents can improve patient outcomes and require early referral
References available on request.
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Author competing interests: nil relevant disclosures.
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