Resultant greenhouse gases from the use of inhaled corticosteroid based on Global Initiative for Asthma (GINA) guidelines: a primary care used case from Singapore

Inhaled corticosteroid (ICS) is recommended by Global Initiative for Asthma 2022 Guidelines for patients to attain asthma control. However, inhalational short-acting β2-agonist (SABA) is needed for reliever therapy and emits greenhouse gases (GHG). Despite evidence supporting ICS-formoterol's superior effectiveness as both maintenance and reliever therapy, and more recent guidelines as the preferred treatment option, some patients continue to be prescribed with ICS. The study aimed to quantify GHG from adults on ICS inhalers treated in primary care in Singapore, including their SABA use, and compare good versus suboptimal asthma control. Data from nine public primary care clinics in eastern Singapore were retrieved from the electronic medical records, comprising asthma-diagnosed patients aged 21 years and older. Records contained their demography, clinical diagnoses, asthma control test (ACT) scores and ICS (beclomethasone pMDI, budesonide DPI and fluticasone pMDI) dispensed from in-house pharmacies. Patients with ACT ≥ 20 were classified as having good asthma control. Total GHG resulting from ICS and SABA were calculated for pMDI or DPI inhalers. Between 2015 and 2023, patients on ICS decreased from 3647-2265, while proportion of well-controlled asthma improved from 53.6-82.5%. Annual GHG emissions showed substantial reductions: ICS-only emissions fell from 101,685-71,899 kgCO₂e, and ICS+SABA emissions decreased from 629,989-316,283 kgCO₂e. Individual patient emissions dropped from 173 kgCO₂e (2015) to 140 kgCO₂e (2023). Patients using Fluticasone propionate inhalers had the highest GHG emissions (227 kgCO₂e/year). Patients with suboptimal asthma control produced significantly higher GHG emissions, exceeding those with good control by 30 kgCO₂e /year (p < 0.001). GHG emissions declined with fewer ICS-treated patients over the years, accompanied by a reduction in per patient GHG emission. Suboptimal asthma control was associated with higher GHG, demonstrating the interdependency between asthma outcomes and environmental sustainability.