Study reveals the importance of inhaler adherence in severe asthma – even after starting biologics

The research, conducted at the Northern Ireland Regional Severe Asthma Centre and funded by the HDR UK’s Inflammation and Immunity Driver Programme and Northern Ireland Chest, Heart and Stroke, followed 207 adults with severe asthma for up to seven years. Researchers tracked patients’ use of inhaled corticosteroids and long-acting β2-agonists (ICS/LABA) using community pharmacy dispensing records and measured the clinical effects of poor adherence.

Biologics are a transformative treatment for severe asthma. However, the study found that one in three patients showed poor inhaler use one year after beginning biologics. These patients experienced significantly more asthma exacerbations over the long term.

Lead author Amy Shackleford, PhD student at Queen’s University Belfast, said: “The introduction of biologics as a treatment for severe asthma has little impact on population level ICS/LABA adherence. However, substantial changes do occur at the individual level. Identifying these patients and tackling this poor adherence is important as these patients are more likely to experience exacerbations and have higher FeNO.”

Although patient prescription records are checked by the specialist clinical team to ensure patients were at least 80% adherent to their ICS/LABA prior to biologic introduction, poor adherence based on dispensing records was still observed in the study. The authors say this highlights that assessing adherence is complex and the use of dispensing records provides a different picture of a patient’s adherence but these are often difficult to obtain. 

Patients with poor adherence prior to starting biologics were more likely to come from deprived backgrounds and had higher levels of airway inflammation, as indicated by fractional exhaled nitric oxide (FeNO). Because of this the authors suggest that novel approaches such as short-term digital monitoring with FeNO monitoring (FeNO suppression testing) may be better to quickly identify subjects requiring biologic treatment or those who would benefit from adherence intervention and support.

The lack of a gold standard for measuring adherence in asthma patients means identifying non-adherent patients is difficult. Whilst our study identified a substantial minority of non-adherent patients using dispensing records, these same patients were deemed adherent when using prescription records. Our results highlight that supplementing these surrogate measures of adherence with novel objective measures, such as FeNO suppression testing using digital monitoring of inhaler use, is beneficial, however they can be more expensive to deliver. 

The findings suggest that clinicians should not assume patients will remain adherent whilst being given biologics. Instead, they should receive ongoing counselling and personalised support to stick to their inhaled treatment plans.

The authors say that a more holistic approach to asthma care is needed, combining medical innovation with behavioural support.

“Despite good evidence that identification of patients for biologic therapy is improved using digital monitoring of inhaled corticosteroids aligned with biomarker assessment (FeNO and blood eosinophil count) to assess therapeutic response,” said Ms Shackleford, “We continue to assess adherence using prescription records, which neither ensures a patient is taking their inhaled treatment (as evidenced by this study using dispensing records) or is responding adequately to optimised inhaled treatment.”

The research team is based at leading UK institutions, including Queen’s University Belfast, Belfast Health and Social Care Trust, and Swansea University.

The study was funded by Northern Ireland Chest, Heart and Stroke and HDR UK’s Inflammation & Immunity Driver Project.

Full citation:

Shackleford, A., Heaney, L. G., McDowell, P. J., Davies, G. A., Butler, C., Sweeney, J., & Busby, J. (2025). Investigating the Association Between Biologic Initiation and Medication Adherence in Severe Asthma: An Analysis of Linked Data. The journal of allergy and clinical immunology. In practice, S2213-2198(25)00610-5. Advance online publication. https://doi.org/10.1016/j.jaip.2025.06.029