Asthma Prescribing Choice Affects Greenhouse Gas Emissions

Diana Swift

November 15, 2019

The healthcare sector generates approximately 4.6% of global emissions, but physicians can shrink the carbon footprint and cut drug costs too by switching patients with asthma from a metered-dose inhaler (MDI) to one of the cheapest brands of dry powder inhalers (DPIs), researchers say.

Using the National Health Service (NHS) digital database, Alexander J. K. Wilkinson, BMBCh, MRCP, a chest physician at the East and North Hertfordshire NHS Trust in Stevenage, United Kingdom, and colleagues analyzed prescription data to calculate 2017 prescription costs and greenhouse gas emissions for different classes of inhalers. They published their findings online October 29 in BMJ Open.

Calls to reduce the adverse impact of inhalers grow, with one study suggesting that five doses could generate the carbon equivalent of a 9-mile car trip.

The researchers found that replacing MDIs using hydrofluoroalkane (HFA) propellant with the cheapest equivalent DPI would decrease drug costs in England by £8.2M (about $10.6 million) annually for every 10% of MDIs changed to DPIs.

"These potential savings would exceed the cost of switching the larger volume of salbutamol MDIs to DPIs, because the incremental cost per salbutamol inhaler (< £2/inhaler) is much lower," the authors write.

If physicians maintained the same prescribing patterns for DPI brands as in 2017, however, drug costs would rise annually by £12.7M (about $16.4 million) for every 10% of MDIs switched to DPIs. That's because most of the potential savings would derive from the cheaper, long-acting beta-agonist inhaled corticosteroids, the authors say.

On the environmental front, for every 10% of MDIs changed to DPIs, 58 kilotonnes of CO2 equivalents (CO2e) could be saved annually in England. "Changing one MDI device to a DPI could save 150 [kilograms (kg)] - 400 kg CO2e annually; roughly equivalent to installing wall insulation at home, recycling or cutting out meat," the authors write.

They explain that some reliever inhalers such as Ventolin have a carbon footprint surpassing 25 kg CO2e per inhaler, whereas Salamol has a carbon footprint of < 10 kg CO2e per inhaler. Long-acting beta-agonist inhaled corticosteroid inhalers (Flutiform, for example) have a carbon footprint of more than 36 kg CO2e compared with an HFA134a combination inhaler such as Fostair, which has a burden of < 20 kg CO2e.

An important question remains whether to switch to DPIs now or wait for reformulated MDIs with novel low-global-warming-potential propellants, the researchers write.

The results may not apply to the United States, as they refer to a single-formulary and single-payer model in which it's easier to make broad changes, pulmonologist S. Christy Sadreameli, MD, an assistant professor of pediatrics at Johns Hopkins University School of Medicine in Baltimore, Maryland, cautioned. "Still, this is a thought-provoking paper and interesting in the context of historical changes in inhaler design, since many healthcare providers are familiar with the switch from chlorofluorocarbon propellants to HFA propellants in pressurized MDIs in the 1990s to reduce environmental impact," she said. Sadreameli was not involved in the study.

She expressed concern, however, that although switching to DPIs — which require breath activation — might work for healthy adults and adolescents, the change might result in treatment failure for pediatric patients or those with physical or developmental challenges.

The researchers say this is an urgent issue. "Climate change is a huge and present threat to health which will disproportionately impact the poorest and most vulnerable on the planet, including people with pre-existing lung disease. Every effort must be made to minimise [greenhouse gas] release to protect current and future generations from the worst effects of climate change," they conclude.

This study received no specific funding.

Smith reports personal fees from medical practice, grants from NHS England, and personal fees from World Health Organization Europe, Better Value Healthcare, Cambridgeshire County Council, and University of Cambridge outside the submitted work.

BMJ Open. Published online October 29, 2019. Full text

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