The Use of Fractional Exhaled Nitric Oxide (FeNO) and Induced Sputum in the Identification of Non-adherence in Difficult to Control Asthma

Asthma usually responds to standard doses of inhaled steroids with or without additional therapies to control their symptoms. However, approximately 5-10% do not respond to this treatment strategy and are referred to as having difficult asthma. Evidence shows that this poor response is not always related to asthma severity with non-adherence to treatment being a common underlying problem, in 35% of subjects. Recognising non-adherence in the clinic is problematic as there is no straightforward objective test to identify it.

Patients attending an asthma clinic whose symptoms are not controlled by standard treatment will be assessed for airway inflammation using fractional exhaled nitric oxide, and sputum analysis. These subjects will be observed taking their medication to determine if this reduces their level of airway inflammation. Prescription records will be used to ascertain if this test distinguishes those who are non-adherent with their treatment from those adults who have severe asthma.

Identifying patients who are non-adherent to treatment will allow an appropriate change in management and enable alternative strategies to be developed to tackle non-adherence in this population. Distinguishing patients who are adherent to treatment but have therapy resistant disease would significantly improve treatment effectiveness in this group by allowing these patients to be suitably targeted with expensive novel therapies such as Omalizumab.