Switching asthma patients 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 study.
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.
Prof Ashley Woodcock from the University of Manchester, who led the investigation, suggested that asthma patients were often unaware of the impact their inhalers, using hydrofluorocarbon as a propellant, had on greenhouse gases.
"Each puff of a [metered dose inhaler] 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 20th of that," he said.
12-Month Study
The study, published in the journal Thorax, 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 those, 1081 were randomised to receive fluticasone furoate/vilanterol via GSK's Ellipta DPI, while 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 and/or an increase from baseline of ≥3, for the group using DPIs was approximately twice that of those who continued using pMDI (adjusted OR 1.91, 95% CI 1.57 to 2.33). The difference was consistent over the 12-month treatment period.
Participants who switched to DPIs were prescribed approximately one less salbutamol inhaler over the 12-months compared with those who continued with usual care (7.2 vs 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. 80% remained on a metered dose inhaler in the usual care group, and 85% remained on a dry powder inhaler 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 to 114) in the switch group compared with 240 kg (95% CI 229 to 252) in those continuing with usual care.
"This is an easy win for the NHS to cut its carbon footprint," Prof 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.
Lead Image Credit: Dreamstime
