Asthma is not well controlled in about half of patients with the disease in the UK and Europe, increasing the risk of hospital admission and severe illness, and increasing healthcare costs.
Now, the authors of a new study have reported that poorly controlled asthma is also associated with a higher carbon footprint, eight times higher than that of well-controlled asthma and equivalent to the greenhouse gas emissions produced by more than 124,000 homes each year in the UK.
The study was published in the journal Thorax and is part of the Healthcare-Based Environmental Cost of Treatment (CARBON) programme, which aims to provide a broader understanding of the carbon footprint associated with respiratory care.
John Bell, BMBCh, medical director of BioPharmaceuticals Medical, AstraZeneca, and co-author of the study, said that he was surprised by the scale to which poorly controlled asthma contributed to the overall carbon footprint of asthma care. “This suggests that suboptimal asthma care is not just a public health issue, but also one which has environmental consequences,” he said.
Improving the care of asthma patients could help the NHS meet its net zero target, the authors suggested.
SABA – Largest Contributor to Asthma-Related Greenhouse Gases
Healthcare is a major contributor to greenhouse gas emissions. In 2020, the NHS set an ambitious target of reducing its carbon footprint by 80% over the next 15 years, with the aim of reaching net zero by 2045.
To estimate the environmental footprint of asthma care in the UK, the researchers retrospectively analyzed anonymized data of 236,506 people with asthma submitted to the Clinical Practice Research Datalink between 2008 and 2019.
Greenhouse gas (GHG) emissions, measured as carbon dioxide equivalent (CO2e), were then estimated for asthma-related medication use, healthcare resource utilization, and severe exacerbations.
Well-controlled asthma was considered as having no episodes of severe worsening symptoms and fewer than three prescriptions of short-acting beta-agonists (SABAs) reliever inhalers in a year. Poorly controlled asthma included three or more SABA canister prescriptions or one or more episodes of severe worsening symptoms in a year.
Almost one in two patients with asthma (47.3%) were categorized as being poorly controlled.
The researchers estimated the overall carbon footprint attributed to asthma care when scaled to the entire UK asthma population was 750,540 tonnes CO2e/year, with poorly controlled asthma contributing to excess GHG emissions of 303,874 tonnes CO2e/year.
“Poorly controlled asthma generated three-fold higher greenhouse gas emissions per capita compared with well-controlled asthma, when taking into account GHG emissions related to all aspects of asthma care, including routine prescribing and management,” Dr. Bell explained. It also generated eight-fold higher excess per capita carbon footprint compared to well-controlled asthma.
SABA relievers represented the largest contributors to per capita asthma-related GHG emissions, accounting for more than 60% of overall GHG emissions and more than 90% of excess GHG emissions. The remainder was mostly due to healthcare resource utilization, such as GP and hospital visits, required to treat severe worsening symptoms.
The researchers acknowledged various limitations to their findings, including that the study results were largely descriptive in nature. And factors other than the level of asthma symptom control, such as prescribing patterns, may also have contributed to high SABA use.