Assessing Medication Adherence in Adults with Asthma and Its Effect on Rescue Therapy for Exacerbations Koh

Yi Ling Eileen Koh ¹ Kian Yong Kenny Chua ^2,3 Ng Ding Xuan ¹ Wai Keong Aau ¹ Ngiap Chuan Tan ^1,4*

• ¹ SingHealth Polyclinics, Singapore, Singapore
• ² National University of Singapore, Institute of System Science, Singapore, Singapore
• ³ Defence Science and Technology Agency, Singapore, Singapore
• ⁴ SingHealth-Duke NUS, Family Medicine Academic Clinical Program, Singapore, Singapore

Introduction: Adherence to prescribed inhaled controller medication is a determinant of asthma health outcomes. Traditional methods for assessing medication adherence (MA) can be challenging in realworld clinical settings. A new behavioral science approach presents opportunities to develop novel MA assessment tool which also allows prediction of acute asthma exacerbations. The study aims to evaluate MA among adults with asthma based on their prescription collection behavior and its relationship with subsequent exacerbations.Method: This retrospective database study involved Asian adults with clinically diagnosed asthma managed in public primary care clinics in Singapore from 2016 to 2023. Their data, including sociodemographical, clinical (including Asthma Control Test scores) and prescriptions records to determine MA. They were categorized to the Full Collection (FC) group for those collection of prescribed asthma medication within a week; Partial Collection (PC) group for partial medication collection; No Collection (NC) group for no dispensation record within one year of the prescription date. The Proportion of Days Covered (PDC), defined as the proportion of days in which a patient has access to the medication was computed to correlate with prescription collection method. Multiple stepwise logistic regression was used assess MA with rescue therapy (RT) occurrence as indicators of acute asthma exacerbations.Results: Complete records of 13,482 patients were analyzed. They were categorized into: FC (23.2%), PC (72.9%), and NC (3.9%) groups. Those who had PC or NC were more likely to have RT in the following year (19.5% and 9.4%), compared to FC (5.2%). Patients with RT had higher oral steroid dispensed compared to those without RT (mean (SD) of 319.7(273.7) vs 143.6(175.8) compared to those without RT (0.78 [0.26] vs 0.81 [0.29]). Logistic regression analysis revealed that PC and NC were more likely to experience RT in the following year (partial: 2.364 (1.964-2.847), p<0.001); no collection: 2.030 (1.318-3.127), p= 0.001). Lower minimum ACT score (0.317 vs 1.0) were noted for PC group and increase minimal ACT score of 0.167 for every unit increase in PDC.Patients in FC group exhibited higher MA and were less likely to receive RT due to asthma exacerbation in subsequent year.