Dynamics of inhaled corticosteroid use are associated with asthma attacks

Joy Lee*, Jacqueline Huvanandana, Juliet M. Foster, Helen K. Reddel, Michael J. Abramson, Cindy Thamrin, Mark Hew

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
16 Downloads (Pure)


Inhaled corticosteroids (ICS) suppress eosinophilic airway inflammation in asthma, but patients may not adhere to prescribed use. Mean adherence—averaging total doses taken over prescribed—fails to capture many aspects of adherence. Patients with difficult-to-treat asthma underwent electronic monitoring of ICS, with data collected over 50 days. These were used to calculate entropy (H) a measure of irregular inhaler use over this period, defined in terms of transitional probabilities between different levels of adherence, further partitioned into increasing (Hinc) or decreasing (Hdec) adherence. Mean adherence, time between actuations (Gapmax), and cumulative time- and dose-based variability (area-under-the-curve) were measured. Associations between adherence metrics and 6-month asthma status and attacks were assessed. Only H and Hdec were associated with poor baseline status and 6-month outcomes: H and Hdec correlated negatively with baseline quality of life (H:Spearman rS = − 0·330, p = 0·019, Hdec:rS = − 0·385, p = 0·006) and symptom control (H:rS = − 0·288, p = 0·041, Hdec: rS = − 0·351, p = 0·012). H was associated with subsequent asthma attacks requiring hospitalisation (Wilcoxon Z-statistic = − 2.34, p = 0·019), and Hdec with subsequent asthma attacks of other severities. Significant associations were maintained in multivariable analyses, except when adjusted for blood eosinophils. Entropy analysis may provide insight into adherence behavior, and guide assessment and improvement of adherence in uncontrolled asthma.

Original languageEnglish
Article number14715
Pages (from-to)1-12
Number of pages12
JournalScientific Reports
Issue number1
Publication statusPublished - 19 Jul 2021
Externally publishedYes

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Copyright the Author(s) 2021. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


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