A recent study has found that switching from pressurised inhalers to dry powder alternatives could be a safe way of cutting the carbon footprint of people with asthma

doctor with inhalers

Switching patients with asthma from a pressurised metered dose inhaler (pMDI) to a dry powder inhaler (DPI) for maintenance therapy more than halves their carbon footprint without loss of asthma control, according to a recent study published in the journal Thorax.

The researchers said the substitution was a worthwhile option to cut greenhouse gases for people who safely managed their asthma at home, and also that switching from pMDI to DPI rescue medications could further reduce CO2 emissions.

Professor Ashley Woodcock of the University of Manchester, who led the investigation, suggested that patients with asthma were often unaware of the impact their inhalers, using hydrofluorocarbon as a propellant, had on greenhouse gases.

‘Each puff of [a pMDI] is equivalent to driving 1 mile in a family car, so one inhaler is close to driving 200 miles … but a powdered inhaler is about a twentieth of that’, he said.

Twelve-month study

The study was conducted in association with Uppsala University in Sweden, and sponsored by GlaxoSmithKline (GSK).

The researchers carried out a 12-month, open-label analysis of 2236 adult participants in the Salford Lung Study, who at baseline were using a pMDI inhaler to control their condition. Of them, 1081 were randomised to receive fluticasone furoate/vilanterol via GSK’s Ellipta DPI, whereas 1155 continued with their usual pMDI treatment.

All the participants, who were matched for the severity of symptoms, were assessed using the Asthma Control Test (ACT) at baseline and at 12, 24, 40, and 52 weeks, while being managed under conditions closely reflecting everyday clinical practice.

Clinical outcomes

Asthma control improved in both treatment arms during the study. 

By week 24, the odds of responding well to treatment—with an ACT total score of 20 or greater and/or an increase from baseline of 3 or greater—for the group using DPIs was approximately twice that of those who continued using a pMDI (adjusted odds ratio 1.91; 95% confidence interval [CI] 1.57–2.33). The difference was consistent over the 12-month treatment period.

Participants who switched to DPIs were prescribed approximately 0.8 fewer salbutamol inhalers over the 12 months, compared with those who continued with usual care (7.2 versus 8), the researchers reported.

Patients were allowed to change their type of inhaler during the study, but most remained with the type they had been assigned. Eighty percent remained on a pMDI in the usual care group, and 85% remained on a DPI in the ‘switch’ group.

Reduced carbon footprint

The researchers calculated that the annual carbon footprint saving for each patient in the switch group was 132 kg of CO2 emissions: 108 kg (95% CI 102–114) in the switch group compared with 240 kg (95% CI 229–252) in those continuing with usual care.

‘This is an easy win for the NHS to cut its carbon footprint’, Professor Woodcock said in an accompanying podcast, ‘especially because the UK is very much an outlier in its use of high carbon inhalers.’

The carbon footprint caused by hydrofluorocarbon propellants in metered dose inhalers is three times more in the UK than in Europe, where low-carbon inhalers are predominantly used.

He added: ‘Essentially, this is about evolution, not revolution. In discussion with patients, healthcare professionals should have a conversation about the environmental footprint of their inhalers.’

Study co-authors Alison Moore, Lucy Frith, and David Leather are employees of GlaxoSmithKline, which funded the investigation.

This article was originally published on Medscape, part of the Medscape Professional Network.

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