Switching to dry-powder inhaler cut carbon footprint without loss of asthma control

Patients with asthma who switched from a metered-dose inhaler to a dry-powder inhaler cut their inhaler carbon footprint by more than half, without loss of asthma control, according to data published in Thorax.

“Chlorofluorocarbons (CFCs) were banned from being used as aerosol propellants under the 1987 Montreal Protocol agreement due to their harmful effects on global warming and ozone depletion. While the hydrofluorocarbons (HFCs) that replaced CFCs in pressurized metered dose inhalers do not deplete the ozone layer, they are potent greenhouse gasses, which are now planned to be phased down under the Kigali Amendment to the Montreal Protocol in 2016, and through national F-gas regulations in Europe and the USA,” Ashley Woodcock, MD, associate dean of clinical affairs at the Manchester Academic Health Sciences Centre at the University of Manchester, U.K., and colleagues wrote. “HFC [pressurized metered-dose inhalers] account for 3% to 4% of the total carbon footprint related to healthcare in the U.K., with the majority of emissions associated with use and disposal of [pressurized metered-dose inhalers] rather than their manufacture. To put this in context, a single dose from an HFC-134a [pressurized metered-dose inhaler] is approximately equivalent to driving 1 mile in a family car.”

The researchers conducted a post hoc analysis of 2,236 patients in the Salford Lung Study in Asthma who, at baseline, were using a pressurized metered-dose asthma inhaler. All patients were randomly assigned to receive fluticasone furoate/vilanterol (Breo Ellipta, GlaxoSmithKline) via a dry-powder inhaler (n = 1,081; mean age, 49 years; 59% women) or continued using a pressurized metered-dose inhaler (n = 1,155; mean age, 49 years; 57% women).

Researchers calculated the annual carbon dioxide equivalent for the total number of maintenance and rescue inhalers prescribed to patients and evaluated asthma control from the proportion of Asthma Control Test (ACT) responders with a total score of at least 20 and/or a 3 or more increase from baseline.

The annual carbon dioxide equivalent per patient was significantly lower among patients using a dry-powder inhaler compared with those using a pressurized metered-dose inhaler (108 kg vs. 240 kg; P < .001).

Compared with patients using a pressurized metered-dose inhaler, the carbon footprint of maintenance therapy alone was 10-fold lower among patients using a dry-powder inhaler (118 kg vs. 11 kg).

In addition, the amount of rescue medication, nearly all salbutamol pressurized metered-dose inhalers, was lower among patients using a dry-powder inhaler (88 kg vs. 109 kg). Those who switched to a dry-powder inhaler were prescribed around one less rescue salbutamol metered-dose inhaler than those who continued usual care.

The odds of being an ACT responder were twice as high among those using a dry-powder inhaler compared with those using a pressurized metered-dose inhaler (adjusted OR = 1.91; 95% CI, 1.57-2.33; P < .001). This difference remained consistent over 12 months of treatment.

The researchers calculated that the annual carbon footprint saving for each patient in the switch group was 130 kg CO₂ emissions, according to a press release. Scaled up, this “would represent approximately 40% of the total carbon footprint due to [metered-dose inhalers] in the U.K.,” the researchers wrote.

“The remaining inhaler carbon footprint could be further reduced through switches from pressurized metered-dose inhaler to rescue medications in dry-powder inhalers or to alternative lower-carbon footprint rescue inhalers if and when they become available,” the researchers wrote.