Can Switching Inhalers Reduce Your Carbon Footprint?

Patients who switched from a pressurized metered dose inhaler (pMDIs) to a dry powder inhaler (DPI) halved their carbon footprints while still maintaining good asthma control, a post-hoc analysis of the Salford Lung Study in Asthma showed.

Including both maintenance and rescue asthma treatment, the annual per-patient carbon footprint equivalent (CO₂e) dropped from a least squares (LS) geometric mean of 240 kg CO₂e for those on a pMDI to 108 kg CO₂e with a DPI (P<0.001), Alison Moore, MD, of GlaxoSmithKline in Brentford, England, and colleagues reported in Thorax.

For context, the carbon footprint of flying from New York to Miami is approximately 215 kg CO₂e per passenger.

“[The DPI] doesn’t lose asthma control — that’s the key. You actually improve asthma control,” Woodcock said in a BMJ podcast. “This is low hanging fruit to reduce our carbon footprint.”

Approximately 70% of inhalers dispensed in England are pMDIs, accounting for 3.5% of the National Health Service’s greenhouse gas emissions.

The study group added that “the U.K. is an outlier compared with the rest of Europe in its high continued use of pMDIs.” A 2020 research letter by co-author Christer Janson, MD, PhD, of Uppsala University in Sweden, found that if England had the same distribution of pMDIs as Sweden, where pMDIs accounted for 13% of inhalers, England would reduce its inhaler carbon footprint by 550 kilotons of CO₂e.

The British Thoracic Society recommends using DPIs, but as the authors noted, switching to DPIs can be more costly than using pMDIs.

The study group examined a subset of data from a 2017 open-label study led by Woodcock, where adults with asthma were randomized to either take fluticasone furoate/vilanterol (FF/VI) via the ELLIPTA DPI or continue usual care. The present study included only those participants who used a pMDI prior to the study, totalling approximately half the original study population (2,236 of 4,233).

Asthma control was measured with the Asthma Control Test (ACT) at baseline, 12, 24, 40, and 52 weeks of treatment. Rescue medication was measured as the total salbutamol/albuterol inhalers prescribed over the 12-month treatment period.

The primary endpoint was asthma control at 24 weeks. Carbon footprint was determined using data from a 2019 study conducted by Janson’s group.

Study participants were a mean age of 49, 57-59% were female, and the mean ACT score at baseline was comparable between groups (16.6 in the usual care group vs 16.5 in the FF/VI group).

While asthma control improved in both study arms, it was “consistently superior over the 12 months” in participants randomized to the FF/VI DPI group, the study group said. At 24 weeks, the odds of being an ACT responder — defined as having ACT score over 19, indicating well controlled asthma, and/or an improvement from baseline score ≥3 — were nearly twice as high in the FF/VI group compared to the usual treatment group (76% vs 63%, adjusted OR 1.91, 95% CI 1.57-2.33, P<0.001).

When looking at maintenance therapy alone, the results were more pronounced. The carbon footprint in the FF/VI group was 10 times lower than in the usual care group (LS geometric mean of 11 kg vs 118 kg, respectively, P<0.001).

In fact, the majority of the carbon footprint in the DPI group came from rescue medication, Woodcock said.

Even then, patients who switched to DPI were prescribed on average nearly one less salbutamol/albuterol rescue inhaler during the study period (LS mean of 7.2 vs 8 inhalers). This translated into a lower carbon footprint from rescue medication in the DPI group as well (LS geometric mean of 88 kg DPI vs 109 kg usual care, P<0.001).