The term difficult asthma generally refers to a clinical situation where a prior diagnosis of asthma exists, and asthma-like symptoms and asthma attacks persist despite prescription of high-dose asthma therapy. There is no definition of difficult asthma in children or adults that is universally agreed, and specifically at what level of treatment prescription or asthma attack frequency the term difficult asthma should apply. Consequently there are no precise data on the prevalence of this clinical problem. Previous consensus studies have suggested failure to achieve symptom control despite prescribed high-dose ICS as a minimum requirement, or have stipulated a treatment level equivalent to at least high-dose ICS (adults) or medium-dose ICS (children) plus a LABA or LTRA before labelling as ‘difficult’.⁶⁸², ⁶⁸³

In this guideline difficult asthma is defined as persistent symptoms and/or frequent asthma attacks despite treatment with high-dose ICS (adults) or medium-dose ICS (children) plus a LABA (age 5 and over) or LTRA; or medium-dose ICS (adults) or low-dose ICS (children) plus a LABA (age 5 and over) or LTRA and an appropriate additional therapy (see specialist therapies - theophyllines); or continuous or frequent use of oral steroids (see specialist therapies - continuous or frequent use of oral steroids).

 

 

Poor adherence

Poor adherence with asthma medication is associated with poor asthma outcome in adults and children (see adherence).

There is a need to identify patients who have poor control solely as a result of poor adherence to simple therapies that are currently available. In theory, improving adherence through monitoring and intervention could potentially reduce asthma attacks, target resources for genuine therapy-resistant cases and reduce overall health costs by minimising asthma attacks, hospitalisation and health resource use.

Monitoring adherence is likely to be beneficial to asthma control and there is some evidence that it can improve lung function and quality of life.⁶⁹¹ Adherence monitoring based on self assessment is unlikely to be accurate and objective measures are therefore needed.

 

Psychosocial factors

Fatal and near-fatal asthma have been associated with adverse psychosocial factors (see section adverse psychosocial and behavioural factors).

 

 

 

Dysfunctional breathing

Observational uncontrolled studies in patients with difficult asthma have identified high rates of dysfunctional breathing as an alternative or concomitant diagnosis to asthma. The dysfunctional breathing may cause symptoms that mimic asthma or coexist with asthma, worsening symptoms.⁹⁷, ⁶⁸⁵

 

 

Allergy

Acute asthma has been associated with IgE-dependent sensitisation to indoor allergens.⁷⁰⁴

 

 

Monitoring airway response

 

1. 97. Heaney LG, Conway E, Kelly C, Johnston BT, English C, Stevenson M, et al. Predictors of therapy resistant asthma: outcome of a systematic evaluation protocol. Thorax 2003;58(7):561-6.
2. 682. Chung KF, Godard P, Adelroth E, Ayres J, Barnes N, Barnes P, et al. Difficult/therapy-resistant asthma: The need for an integrated approach to define clinical phenotypes, evaluate risk factors, understand pathophysiology and find novel therapies. European Respiratory Journal 1999;13(5):1198-208.
3. 683. Prys-Picard CO, Campbell SM, Ayres JG, Miles JF, Niven RM, Consensus on Difficult Asthma Consortium UK. Defining and investigating difficult asthma: developing quality indicators. Respiratory Medicine 2006;100(7):1254-61.
4. 685. Robinson DS, Campbell DA, Durham SR, Pfeffer J, Barnes PJ, Chung KF, et al. Systematic assessment of difficult-to-treat asthma. European Respiratory Journal 2003;22(3):478-83.
5. 691. Apter AJ, Wang X, Bogen DK, Rand CS, McElligott S, Polsky D, et al. Problem solving to improve adherence and asthma outcomes in urban adults with moderate or severe asthma: A randomized controlled trial. Journal of Allergy and Clinical Immunology 2011;128(3):516-23.e5.
6. 704. Position statement. Environmental allergen avoidance in allergic asthma. Ad Hoc Working Group on Environmental Allergens and Asthma. J Allergy Clin Immunol 1999;103(2 Pt 1):203-5.