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J Allergy Clin Immunol Pract. 2018 Nov - Dec;6(6):1989-1998.e3. doi: 10.1016/j.jaip.2018.03.008. Epub 2018 Apr 5.

Relationship of Inhaled Corticosteroid Adherence to Asthma Exacerbations in Patients with Moderate-to-Severe Asthma.

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Department of Respiratory Medicine, University of Ferrara, Ferrara, Italy.
Allergy and Respiratory Research Group, Usher Institute of Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK; Optimum Patient Care, Cambridge, UK.
Instituto de Investigación Hospital Universitario de la Princesa (IISP), Universidad Autónoma de Madrid, Madrid, Spain.
Observational and Pragmatic Research Institute, Singapore; Inhalation Consultancy Ltd, Yeadon, UK.
Section of Respiratory Medicine and Allergology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
Servei de Pneumologia (Institut del Tòrax), Hospital Clínic-IDIBAPS-CIBERES, Universitat de Barcelona, Barcelona, Spain.
Department of Medicine, Respirology, McMaster University, Hamilton, Ontario, Canada.
Optimum Patient Care, Cambridge, UK.
Observational and Pragmatic Research Institute, Singapore.
Observational and Pragmatic Research Institute, Singapore; Academic Primary Care, University of Aberdeen, Aberdeen, UK. Electronic address:



Patients with asthma and elevated blood eosinophils are at increased risk of severe exacerbations. Management of these patients should consider nonadherence to inhaled corticosteroid (ICS) therapy as a factor for increased exacerbation risk.


The objective of this study was to investigate whether poor adherence to ICS therapy explains the occurrence of asthma exacerbations in patients with elevated blood eosinophil levels.


This historical cohort study identified patients within the Optimum Patient Care Research Database, aged 18 years or more, at Global Initiative for Asthma step 3 or 4, with 2 or more ICS prescriptions during the year before the clinical review. Patient characteristics and adherence (based on prescription refills and patient self-report) for ICS therapy were analyzed for those with elevated (>400 cells/μL) or normal (≤400 cells/μL) blood eosinophils.


We studied 7195 patients (66% female, mean age 60 years) with median eosinophil count of 200 cells/μL and found 81% to be not fully adherent to ICS therapy. A total of 1031 patients (14%) had elevated blood eosinophil counts (58% female, mean age 60 years), 83% of whom were not fully adherent to ICS. An increased proportion of adherent patients in the elevated blood eosinophil group had 2 or more exacerbations (14.0% vs 7.2%; P = .003) and uncontrolled asthma (73% vs 60.8%; P = .004) as compared with non-fully adherent patients.


Approximately 1 in 7 patients had elevated eosinophils. Adherence to ICS therapy was not associated with decreased exacerbations for these patients. Additional therapy should be considered for these patients, such as biologics, which have been previously shown to improve control in severe uncontrolled eosinophilic asthma.


Adherence; Asthma control; Asthma exacerbations; Eosinophils; Inhaled corticosteroids; Severe asthma


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