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Using prednisolone and cortisol assays to assess adherence in oral corticosteroid dependant asthma: an analysis of test-retest repeatability.

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posted on 2020-11-04, 10:49 authored by John Busby, Cecile Holweg, Akiko Chai, Peter Bradding, Rekha Chaudhuri, Adel Mansur, John G Matthews, Andrew Menzies-Gow, James Lordan, Rob Niven, Liam G Heaney, UK Refractory Asthma Stratification Programme (RASP-UK)
BACKGROUND AND OBJECTIVE: Non-adherence is an important issue within severe asthma. Prednisolone and cortisol assays have been proposed as an inexpensive, objective measure of adherence for oral corticosteroid (OCS)-dependent asthmatics, however, little is known about the reliability of these tests. METHODS: 41 severe OCS-dependent asthmatics had their prednisolone and cortisol measured during six study visits over a three month time period. Subjects were classed as non-adherent/variably-adherent if they had undetectable prednisolone and/or cortisol >100 nmol/L. Intraclass correlation coefficients (ICCs) were used to assess the test-retest reliability of prednisolone and cortisol, and Gwets AC1 kappa was used to assess the reliability of the adherence classification. Mean change in blood eosinophils for adherent and variably/non-adherent visits were calculated and linear regression with cluster-robust standard errors was used to test for differences. RESULTS: 30 subjects were included in the analysis. Reliability was poor for prednisolone (ICC: 0.43; 95% CI: 0.27, 0.59), and moderate for cortisol (ICC: 0.60; 95% CI: 0.44, 0.74). Using the combined rule, subjects were classified as adherent during 141 (88%) visits, with 21 subjects (70%) adherent during all study visits. The adherence classification had almost perfect reliability (Kappa: 0.84; 95% CI: 0.74, 0.95). Blood eosinophils were decreased by 47 cells/μl (95% CI: 11, 84) during adherent visits but increased by 65 cells/μl (95% CI: -4, 134; Pdifference=0.03) during variably/non-adherent visits. CONCLUSIONS: Assessing adherence to maintenance OCS using a simple rule based on prednisolone and cortisol assays is highly reliable and correlated with blood eosinophil changes. Clinicians should have confidence in the results of this rule.

History

Citation

Pulmonary Pharmacology & Therapeutics, Volume 64, October 2020, 101951

Author affiliation

Department of Respiratory Sciences, University of Leicester

Version

  • AM (Accepted Manuscript)

Published in

Pulm Pharmacol Ther

Volume

64

Pagination

101951

Publisher

Elsevier BV

issn

1094-5539

eissn

1522-9629

Copyright date

2020

Available date

2021-10-09

Spatial coverage

England

Language

eng

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