Asthma: Phenotyping Exacerbations 3

Exacerbations of asthma (asthma attacks) are very common in the UK. They are frightening for patients, expensive for the health service, and occasionally lead to avoidable deaths. Despite the obvious importance of asthma attacks, they remain poorly understood. Although some of the triggers for attacks are known, the resultant characteristics of attacks are not. Recent research has shown different inflammation profiles associated with asthma attacks; however, this is not well understood, and all asthma attacks are treated the same. Increased knowledge about the nature of asthma attacks may better define these attacks and help develop more targeted treatment options. This study aims to describe the characteristics of patients admitted with asthma attacks. The recovery and response to standard treatment for asthma attacks following discharge from the hospital will also be described. This is achieved by studying the characteristics of asthma attacks in patients hospitalized with acute asthma. Participants will be asked to attend two follow-up visits during which their response to treatment will be described. The study is planned to last for 2.5 years, with a recruitment period of 18 months, and will include 100 participants with acute asthma.

Asthma is a common condition affecting 9.8 million people in the United Kingdom1. Asthma attacks cause nearly 1500 deaths per year in the UK2 and account for over 90,000 hospital admissions and 1800 intensive care admissions costing at least 1 billion pounds a year3. Non-asthma conditions such as Vocal Cord Dysfunction4 and Dysfunctional Breathing Pattern5 can mimic severe asthma and lead to hospital admission and inappropriate asthma treatment with potentially harmful high dose corticosteroids. However, the proportion of patients admitted with these asthma mimics is unclear. The use of biomarkers to guide treatment in stable asthma is now commonplace, but this prospect has not been fully explored in acute asthma attacks. Determining the type of inflammation underlying an attack can, however be tricky because many patients receive oral corticosteroid prior to, or soon after admission, which promptly and markedly affects the most accessible type 2 asthma (T2) biomarkers7, the blood eosinophil count. Measurement of another T2 biomarker, fractional exhaled nitric oxide (FENO), during an attack may prove a useful measure of ongoing T2 airway inflammation, but this strategy requires assessment. Airway obstruction in asthma attacks is assessed and confirmed by measuring peak expiratory flow and/or forced expiratory volumes. These measures are effort-dependent and can, therefore, be unreliable and misleading if improperly performed. We aim to evaluate the potential feasibility and utility of alternative diagnostic methods of assessing airway obstruction and measuring T2 biomarkers to see if these allow the distinction between actual asthma attacks and asthma attack mimics and also if they can distinguish different types of asthma attacks. The pattern of recovery following asthma attacks is also not fully understood. Studies have reported varying recovery times8 and inconsistencies in the response of airway obstruction9 and T2 biomarkers10 to corticosteroid treatment in acute asthma. The investigators hypothesise that a significant proportion of patients admitted to hospital with suspected asthma attacks have an alternate cause for their clinical presentation. To further explore this, The investigators propose an observational study to describe and investigate the characteristics of patients admitted with suspected severe asthma. The investigators will assess the utility of point of care, non-invasive biomarker measurements in identifying pulmonary and extrapulmonary traits in patients hospitalised due to presumed asthma attack. A variety of study assessments will be performed at the baseline visit (exacerbation visit), and two follow up visits following hospital discharge. Results of study assessments obtained during each study visit will be compared and analysed. This is the first study to prospectively investigate acute asthma both during and following exacerbation episodes. This will allow a comprehensive understanding and description of pulmonary and extrapulmonary traits as well as the pattern of recovery following asthma attacks.