Rapid ReviewSevere asthma treatment: need for characterising patients
Section snippets
Definition of severe asthma
Defining asthma severity on the basis of persisting symptoms despite high-dose inhaled steroids is problematic, and systematic evaluations of difficult-to-manage asthma give insight into the role of different factors in this population.8, 9 A universal definition of severe asthma is difficult because of different patterns of disease. For example, frequent severe exacerbations on the background of relatively normal lung function (type 2 brittle asthma10) would be defined by most as severe but
Other diagnoses and exacerbating factors
Several conditions that cause respiratory symptoms might co-exist in asthmatic patients, leading to an apparent failure to respond to therapy. In both systematic evaluations,8, 9 additional or alternative diagnoses were revealed in just over a third of cases (figure). There are several other additional or co-existent conditions that might make asthma difficult to control: smoking and chronic obstructive pulmonary disease, allergic bronchopulmonary aspergillosis, bronchiectasis, chronic
Poor adherence and psychological factors
One of the commonest reasons for a poor response to asthma therapy is not taking medication. The Brompton study9 assessed adherence in those on oral prednisolone: half had low or undetectable serum prednisolone and/or normal cortisol, suggesting non-adherence. In the Belfast cohort,20 11 of 44 patients taking theophylline and 14 of 25 taking prednisolone had unrecordable serum levels of drug. Non-adherence with steroid therapy in this population must be assessed when defining
Therapy-resistant asthma
Therapy-resistant asthma has been defined as persisting symptoms due to asthma despite high-dose inhaled steroids (2000 μg beclomethasone diproprionate or equivalent) plus long-acting β2 agonist, with the requirement for either maintenance systemic steroids or at least two rescue courses of steroids over 12 months and despite trials of add-ons such as a leukotriene-receptor antagonist or theophylline.8 These are the patients for whom omalizumab might be appropriate.
Key to this definition is
Conclusion
Omalizumab holds great promise for difficult-to-control asthma. However, before using expensive new therapies, patients with difficult-to-manage asthma should be systematically characterised so that new treatments are appropriately targeted.
We thank Mina Gaga for helpful discussions. We declare that we have no conflict of interest.
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