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On the way to a consensus on eosinophilic asthma
Guest commentary by Dr. Stephanie Korn
Asthma is a heterogeneous disease, with recognizable clusters of clinical, functional and laboratory characteristics called ‘phenotypes’. Allergic asthma is the most easily recognized phenotype. Among the non-allergic phenotypes eosinophilic asthma (or asthma with eosinophilia), driven by an abnormal production of type 2 cytokines (e.g. interleukin-5 (IL-5) and IL-13) triggered by as yet unknown danger signals, still awaits precise characterization, even more so given the high clinical impact in particular of severe eosinophilic asthma (SEA) and the availability of effective treatment options.
The present manuscript summarizes the results of a discussion among asthma experts on diagnosis, treatment, and follow-up of patients with SEA, as a first step towards a better characterization and management of this asthma subtype. Based on the accepted definition of severe asthma it proposes key major and minor criteria to recognize and properly diagnose SEA in clinical practice, among them high-load blood and sputum eosinophilia as the leading SEA biomarker, exacerbation frequency, dependence on oral corticosteroids, late disease onset, upper airway involvement and fixed airflow obstruction. Equally important are thoughts on how to transfer the results of controlled clinical trials testing biologics directed against IL-5 into a real-life situation, i.e. when and how to best use these drugs in daily practice. The logical next step after identifying SEA patients eligible for and likely to benefit from targeted treatment options is to select the parameters most informative to determine which patients have responded to treatment. The usual suspects, symptoms, lung function, questionnaires, exacerbations, and effects on comorbidities do not always help to answer this question, as treatment responses may be multifactorial and differ among individual patients. It is tempting to speculate about a tool similar to the global evaluation of treatment effectiveness score used to evaluate the clinical response to omalizumab, or an as yet to be defined score based on a combination of clinical, functional and laboratory parameters. Finally, which is the best strategy to monitor SEA patients treated both with and without biologics during long-term follow-up?
The increasing number of effective biological therapies approved for targeted treatment of severe asthma underscores the high clinical need to address and answer these questions. The arguments listed in the present manuscript may help to develop a statement based on evidence and expert opinion to support clinicians in the management of patients not only with severe eosinophilic asthma.
Dr. Stephanie Korn is Head of the Clinical Research Dept. in Pulmology at the Mainz University Hospital.
Severe eosinophilic asthma: a roadmap to consensus
Buhl R, Humbert M, Bjermer L, Chanez P, Heaney LG, Pavord I, Quirce S, Virchow JC, Holgate S; and the expert group of the European Consensus Meeting for Severe Eosinophilic Asthma.
Eur Respir J. 2017 May 1;49(5).