Journal of Asthma and Allergy (Jan 2022)
Determining Persistence with an Inhaled Corticosteroid in Asthma: Assessment Using an Objective Measurement vs the Self-Reported Foster Score
Abstract
Britt Overgaard Hedegaard,1 Kjell Erik Julius Håkansson,2 Frodi Fridason Jensen,2,3 Charlotte Suppli Ulrik,2,4 Ulla Møller Weinreich1,5 1Department of Respiratory Diseases, Aalborg University Hospital, Aalborg, Denmark; 2Department of Respiratory Medicine, Copenhagen University Hospital - Hvidovre, Hvidovre, Denmark; 3Medical Department, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands; 4Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark; 5The Clinical Institute, Aalborg University, Aalborg, DenmarkCorrespondence: Ulla Møller WeinreichDepartment of Respiratory Diseases, Aalborg University Hospital, Mølleparkvej 4, Aalborg, DK-9000, DenmarkEmail [email protected]: Adherence with controller medication is a major challenge in asthma management. Thus, a reliable method of measurement is mandatory to assess adherence.Aim: To examine the test-retest reliability on adherence with inhaled corticosteroids in adults with asthma using, a self-reported adherence score (Foster score).Methods: Patients with asthma and > 1 routine follow-up appointment at a university hospital outpatient clinic reported Foster scores. The objective Medication Possession Ratio (MPR) was calculated based on pharmacy redemption data and physician-prescribed doses of inhaled corticosteroids. The difference between Foster score and MPR at the first and second visit was assessed using a Bland–Altman plot, outcomes reported as limits of agreements and bias. Foster scores from both visits were used to calculate an intraclass correlation coefficient (ICC).Results: Self-reported adherence with asthma controller medication measured by Foster score was significantly higher than the objective MPR (p < 0.0001). The Bland–Altman plot for MPR and Foster score at the first and second visit showed upper and lower limits of agreement of 83.5 – (− 1.6) and 80.9 – (− 6.9) and bias was 41.0 and 37.0, respectively. Of the included patients, 93.1% reported identical Foster scores between visits, resulting in an excellent ICC of 0.92. Absolute median difference between Foster scores and MPR at first and second visit was 8.7 percentage points (p = 0.049).Conclusion: Foster score shows an excellent ICC; however, its poor agreement with objective measures of adherence suggests that clinicians should not rely on Foster scores alone to assess adherence with inhaled corticosteroids in patients with asthma.Keywords: Foster score, medication possession ratio, controller medication, asthma, self-assessed adherence, self-reported outcome, adherence, persistence
