Guideline-based asthma treatment in Asia: Insights from a robust time-in-state model

Abstract

Background: The landscape of guideline-based asthma treatment in Asia remains unclear.

Objective: Leveraging current evidence, we predicted the long-term economic impact of guideline-based asthma treatment in Asian countries, using Singapore as a case study.

Methods: We systematically reviewed evidence between 2014 and 2024 on asthma prevalence, adherence to inhaled corticosteroid (ICS) with or without long-acting β-agonist (LABA), and frequency of short-acting β-agonist (SABA) use in Asian asthma populations. We developed a time-in-state model for the joint impact of ICS/ICS-LABA adherence and SABA use on the economic and humanistic burden of uncontrolled asthma during 2024 to 2043. Accordingly, we projected 20-year total direct costs, indirect costs, and quality-adjusted life-years (QALYs) lost associated with uncontrolled asthma in Singapore and assessed the varied impact of guideline-based asthma treatment.

Results: Among 28 Asia-based, population-level studies, asthma prevalence was 1% to 12% in adults and 2% to 14% in children. ICS/ICS-LABA adherence, reported in only 3 countries, ranged from 10% to 90%; average SABA use was 2.5 to 6.4 canisters/year. In Singapore, under current trends of ICS/ICS-LABA adherence and SABA use, the 20-year burden of uncontrolled asthma is SGD$2.772 billion in direct costs, SGD$5.670 billion in indirect costs, and 58,872 QALYs lost. Optimizing guideline-based treatment nationwide (ICS/ICS-LABA medication possession ratio = 0.8, SABA use = 1 canister/year) reduces 20-year direct costs, indirect costs, and QALYs lost by 27.7%, 23.8%, and 28.8%, respectively.

Conclusions: Population-based evidence on guideline-based asthma treatment in Asia is limited. Population-level modeling of its economic impact, using minimal key evidence, revealed substantial reduction in societal economic and humanistic burden in Asian countries such as Singapore.

Keywords: Asthma; asthma control; asthma management guidelines; inhaled corticosteroid; β-agonist.

Fig 1

Projected 20-year trends of the burden of asthma in Singapore. The gray, blue, and orange bars represent the portion of annual burden attributable to well-controlled, partially controlled, and uncontrolled asthma, respectively. The trend line represents the annual trend of the total burden of all patients with asthma, and the error bars represent the corresponding 95% CIs.

Fig 2

Projected impact of ICS/ICS-LABA adherence and SABA use at baseline on the 20-year burden of uncontrolled asthma. The trend lines represent the trend of the 20-year burden of uncontrolled asthma associated with varied levels of ICS/ICS-LABA adherence (0-1 MPR) and SABA used (1-6 canisters per year) at baseline, and the error bars represent the corresponding 95% CIs of the burden.

Fig 3

Results of a scenario analysis of the current landscape of asthma treatment in Singapore and the corresponding 20-year burden of uncontrolled asthma. The trend lines represent the trend of the 20-year burden associated with uncontrolled asthma across varied scenarios of the current state of asthma medication use under a certain level of asthma prevalence. Specifically, the black trend line represents the projections derived under the base case prevalence of asthma, ie, assuming autoregressive integrated moving average–projected asthma prevalence from GBD 2021 (4.7% in children and 2.6% in adults at baseline). The green trend line represents the projections derived under constant asthma prevalence based on estimates reported in community-based studies (8.9% in children and 2.6% in adults). The red trend line represents the projections derived under constant asthma prevalence based on estimates from the 2010 Singapore Burden of Disease Study (20% in children and 5% in adults). The error bars represent the corresponding 95% CIs of the burden.