Asthma, an inflammatory airway disease, can be life-threatening due to bronchoconstriction during an acute exacerbation. Inhaled corticosteroids (ICS) with or without Long-acting beta-agonists (LABA) are some of the evidence-based therapeutics to mitigate airway inflammation and mitigate asthma exacerbation risks (Cardet et al., 2023). ICS and LABA medications are prescribed by clinicians worldwide in a majority of healthcare settings. However, adherence to these inhaled medications might cause suboptimal outcomes globally (Gamble et al., 2009).

Assessment of medication adherence (MA) is the first pivotal step before considering appropriate and individualized solutions to address the underlying causes. Conventionally, clinicians prescribe different medications which the patients collect from the pharmacy after the consultation. Nonetheless, patients might opt to collect medications in totality, in installments, or not at all. Collection behavior for prescription is a surrogate marker of MA because a patient who collects all the medication presumably takes them regularly based on the prescribed doses.

The methodology of MA assessment of a patient is diverse, ranging from targeted history taking during a clinician-patient consultation, questionnaire-based inquiry, and prescription record review to the use of medical technology such as smart sensors embedded in the inhalers (Amber et al., 2023; Babel et al., 2021). Each method has its own strengths and limitations. Omission in the clinical approach occurs frequently due to limited consultation time, heavy patient load, oversight, and fatigue of clinicians. Incorporating routine use of questionnaires or reviews of manual or electronic prescription records necessitates trained healthcare workers, adequate logistic resources for decision support, clinical information, and redesign of care delivery system, which pose a multitude of challenges.

Prescription collection behavior is a useful tool to assess MA. Patients can choose to collect the medications in totality, in part, or not at all. A patient who collects all the medication is presumably taking them regularly based on the prescribed doses. Patients who filled their prescriptions partially over a stipulated period would suggest that they were not taking their medications regularly, resulting in a balance of medication in which a partially filled prescription was deemed adequate. Such an approach is strengthened by determining the Proportion of Days Covered (PDC) by the medication prescribed. PDC refers to the proportion of days in which a patient has access to the medication (Pharmacy Times, 2015; Shah et al., 2023).

The objective of the current research was to determine the medication adherence of adults with asthma based on their prescription collection behavior, and the proportion of days covered by their prescribed medication. It also aimed to evaluate the association between prescription collection behavior and the occurrence of rescue therapy (RT) as an indicator for acute asthma exacerbations in the subsequent year.

The study is based on retrospective electronic medical record (EMR) data from SingHealth Polyclinics, a public healthcare institution comprising a network of public primary care clinics in eastern Singapore.

Asthma exacerbations are defined as a worsening of asthma symptoms that require medical intervention. They constitute a major cause of morbidity and healthcare utilization, thus highlighting the need for effective management strategies (Global Initiative for Asthma GINA, 2024). Inhaled medications, including ICS and bronchodilators, are fundamental in managing asthma symptoms and improving respiratory function. Long-acting beta-agonists (LABAs), when used in combination with ICS, provide bronchodilation and help improve airflow by relaxing the smooth muscles surrounding the airways (Papi et al., 2020). Inhaled medications offer rapid relief of bronchoconstriction and long-term control when used consistently (Global Initiative for Asthma GINA, 2024). Hence they are more efficient in managing asthma symptoms.

Despite the clear benefits of inhaled medications, adherence remains a significant challenge in asthma management. The effectiveness of different categories of inhaled medications for asthma pharmacotherapy varies but failure to use them regularly will significantly raise the risk of future asthma exacerbations (Yamasaki et al., 2024). To our knowledge, leveraging prescription collection behavior to assess MA is novel in this study, with no precedent to benchmark from published literature. The results show that more than 7 out of 10 patients who collected their asthma medications partially, were likely to reflect their poor medication adherence. It is further substantiated by the computation of PDC, with a score of 0.8, reflecting that patients may not use their medications up to 20% of the time. More rigorous endeavors are needed by healthcare professionals to review the treatment adherence or even re-examine the diagnosis when red flags are raised when their patients choose to collect their medication partially or completely default their prescription.

Adults who collected the medications partially tended to be significantly older, female individuals, and Chinese, receiving subsidized medication and conversely, fewer received financial assistance from the official agency (Table 2). It seems that the cost of the medication is less likely to be a barrier to prescription collection as the inhalers are largely dispensed at subsidized prices to local citizens or permanent residents and financial assistance is readily available to those who could not afford the medications. Older adults may have more co-morbidities and are often treated with other medications aside from inhalers. The resultant polypharmacy is postulated to jeopardize MA. It is suggested that more qualitative research be performed in the future to dive deep into the impact of the socio-demographic factors of these adults on their prescription collection behavior.

Significant association exists between the prescription collection behavior of these adults and their asthma outcome and morbidity (Table 3). Regardless of data shown in Model 1 or 2, those with PC or NC were at higher risks of RT in the following year. Most current models leveraged on data relating to emergency department (ED) visits or hospitalization as the definition for asthma exacerbation, but few have looked at RT as the outcome and in the context of primary care-based asthma management. A systematic review pooled the performance of asthma exacerbation prediction models; of them, 73% were based on hospitalization and ED visits (Xiong et al., 2023). However, asthma is largely managed in primary care. It allows opportunities for pharmacists and clinicians to explore and address their MA as their prescription collection behavior can be readily identified in primary care or community pharmacies.

Prescribing controller medication such as ICS or combination medication (ICS + Long-Acting Beta Agonist or LABA) or switching ICS brand or between ICS and combination medication) had a significant effect on their asthma control status based on the total or individual item score of the Asthma Control test, and the risk of RT in the following year (Table 1). More relievers such as Salbutamol inhalers were inevitably dispensed for those with RT, which is expected based on clinical practice guidelines in treating acute asthma. It is vital to counsel patients on adherence to ICS or combination medication after they are identified with partial prescription collection.

The NC group is far smaller compared with those in the FC and PC groups. It is a subset of the population who are often overlooked unless deliberate efforts are devoted to comparing prescribed and dispensed medications. The current electronic prescription system has yet to automate the computation of such differences. However, their asthma health status was not drastically compromised with low RT risk despite the absence of medication. This group may compromise those with a provisional diagnosis of asthma pending their scheduled spirometry or be collecting their medication from other healthcare providers, including those who were managed by pulmonologists from hospitals.

A paradigm shift in asthma management can emerge in which asthma prescription collection behavior by adults with asthma at the primary care or community pharmacy triggers alerts to pharmacists and clinicians to investigate their MA. Healthcare professionals can explore the reasons for the partial collection of asthma exacerbation occurrences and frequencies during wide-ranging consultations to review their asthma pharmacotherapy and MA. Improving adherence through multidisciplinary primary healthcare professionals, such as pharmacist-patient consultations is another strategy to optimize asthma care (Makhinova et al., 2022). Motivation for self-management, seeking asthma knowledge, improving attitudes, and having a positive trusting relationship with the healthcare provider have been shown to be pivotal factors in enhancing MA (Blake, 2017). Delegating more frequent review of asthma adherence to pharmacists, or other allied health providers who could provide adherence counseling would be a practical alternative (Soones et al., 2017).

In recent years, smartphone-enabled sensors, electronic trackers or reminders, and simplified regimens showed better adherence, reduced rescue inhaler use, and improved Asthma Control Scores (Foster et al., 2014; Normansell et al., 2017). Considering the results of this study, the institution has implemented an automated digital interface to rapidly identify patients who collect their medications entirely or partially when they present themselves at the polyclinic pharmacy. The next step is to design a clinical trial involving such a new care model, especially in a resource-poor community, to evaluate its effectiveness in rapidly identifying and targeting adult patients who collect their medications partially. This measure aims to assess the underlying reasons for the partial collection, including those relating to MA, and individualize the solution and action plan to address any specific deficiencies during the asthma care delivery in the polyclinics.

Overall, it can be concluded that patients who collected full prescriptions of their asthma medications exhibited greater MA and had fewer RT for asthma exacerbations in the following year.