The importance of inhaler adherence in severe asthma and its relationship to clinical outcomes

Patients with asthma who remain troubled with symptoms and asthma attacks despite the use of long acting beta-agonist and inhaled corticosteroid therapy are classed as having severe asthma. Some of these patients have “‘difficult to control’” asthma because of poor adherence or inhaler technique, while others have asthma that is ‘refractory’ to treatment. Identifying and addressing poor adherence to ICS/LABA therapy is essential in management of patients with severe asthma. In clinical trials, adherence assessment ensures that only patients with ‘refractory’ asthma are enrolled and reduces the variance in the results that could result as a consequence of not assessing adherence. In clinical practice assessing and addressing adherence allows appropriate use of biologic therapy. The aim of this thesis was to develop ways to assess adherence to maintenance asthma therapy. Firstly, I conducted a systematic review, investigating whether, and how adherence to inhaled corticosteroids (ICS) and long-acting beta agonist (LABA) is assessed in the screening and run-in phase of randomised controlled trials of ‘add on therapy’ in severe asthma. I found that adherence to ICS/LABA therapy assessment and reporting is rarely done and that the methods used to assess adherence in the randomised controlled trials were inadequate. To overcome these inadequacies, I conducted a randomised clinical trial to assess adherence in patients with severe asthma using the INhaler Compliance Assessment (INCA) device, a digital audio recording device that provides information on inhaler time of use and inhaler technique. I devised pathways that incorporated this information, as well as patient’s symptom scores and peak expiratory flow to design a physician script tailored to optimise asthma treatment. The study assessed the value of using an objective method of assessing inhaler adherence in tailored education therapy and how it guides clinicians to make informed clinical decisions in treating patients with severe asthma.