Greenhouse Gas Emissions Associated With Severe Asthma Care in the United Kingdom

Background: The 2023 United Nations Climate Change Conference (COP28) Declaration on Climate and Health promotes steps to curb emissions and reduce waste in the health sector. Objective: To describe and quantify greenhouse gas (GHG) emissions associated with severe asthma (SA) care in the United Kingdom, by carbon source and transition status from SA to severe uncontrolled asthma (SUA) and/or regular specialist care (RSC). Methods: This was a cohort study using routinely collected data from the Clinical Practice Research Datalink Aurum, Hospital Episode Statistics, and CO2 equivalent emissions data. Patients were ≥12 years old at the index date (ie, date of first recorded inhaled corticosteroid [ICS] + controller prescription) with a validated asthma diagnosis. Total GHG emissions and GHG emissions related to medications, exacerbations, and health care resource utilization (HCRU) were estimated, overall and by transition along stages of the SA-SUA-RSC continuum. Five pathways and stage orders were identified: (1) SA, (2) SA-SUA, (3) SA-RSC, (4) SA-RSC-SUA, and (5) SA-SUA-RSC. Results: The total CO2 equivalent for the SA population (n = 93,054) was 2167 tonnes/10,000 patients/year. GHG emissions were 5.2% to 23.0% greater for patients transitioned to SUA (vs previous stage), mostly due to exacerbation-related emissions (4.2-7.7 times greater; predominantly hospitalizations) and medication-related emissions (3.5%-10.9% greater; predominantly short-acting β2-agonists [SABAs]). Conversely, total GHG emissions decreased by 12.1% to 23.9% for those referred to RSC, due to decreased exacerbation-related emissions (1.7-5.2 times lower; all sources) and medication-related emissions (14.8%-20.6% lower; both SABA and overall ICS). Conclusion: Our findings suggest that RSC not only improves patient outcomes but also reduces GHG emissions in line with aims to reduce the health sector's contribution to the total national carbon footprint.