Minimising the environmental impact of inhaled therapies

To the Editor:

We read with interest the recent editorial by Keeley et al. [1] on the timely topic of changing pressurised metered dose inhalers (pMDIs) to dry powder inhalers (DPIs) due to the much higher carbon footprint of pMDIs [2]. We agree with the authors that global warming cannot be tackled only by focusing on inhaler devices, but as long as we can provide safe and effective treatment to our patients, we cannot overlook environmental facts either. We feel that Keeley et al. [1] gave an unjustified negative impression on the performance of DPIs. They imply that DPIs are more expensive than pMDIs, that switching from pMDI to DPI leads to poorer asthma control, and that patients using DPIs should have a pMDI+spacer rescue pack since DPIs cannot be relied on as rescue medication. However, we feel that these misleading claims are based on wrong interpretations of the publications they cite, or on opinions without any supporting data. Since in many countries, like in Finland and Sweden, good control of asthma and COPD is achieved at a national level [3, 4] while the majority of patients using inhaled therapies are treated with DPIs, (56% in Finland and 71% in Sweden, according to IQVIA standard units volume data for 2019), we think it is worth correcting these wrong impressions.

The authors write that “In many cases, pMDIs are significantly less costly than DPIs and a shift towards greater use of DPIs could cause a substantial increase in healthcare drug costs” and they cite Sakaan et al. [5]. However, the study they cite was about waste of drug doses in patients hospitalised for asthma or COPD and dispensed new inhalers in hospital, not about costs of maintenance treatment at home. The study made no comparison of costs between DPI and pMDI, and there is no statement in the publication that DPI would be more expensive than pMDI. On the contrary, there is a recent study showing that switching maintenance treatment from pMDI to DPI would not only be environmentally friendly but has also potential to reduce costs [6].

Keeley et al. [1] lead the reader to understand that in Finland the government enforced patients to be switched from pMDIs to DPIs leading to impaired disease control. In Finland, there has not been such a governmental enforcement. Although a majority (56%) of patients are treated with DPIs (IQVIA data, 2019), the outcomes of asthma treatment on national level have been very good [3]. The study they cite was conducted in Iceland [7], not Finland, and the study was not at all about inhaler types but about drug classes: in Iceland decrease in use of inhaled corticosteroid (ICS) and ICS plus long-acting β-agonist due to a change in reimbursement policy led to increased use of short-acting β-agonist and oral corticosteroids, and to increased rate of hospitalisations. In this study, nothing suggested that the outcome was in any way related to inhaler type, but it was an expected result of decreased maintenance treatment. On the contrary to what Keeley et al. [1] imply, there are several real-life studies showing that many patients can have their inhaler safely switched [8, 9], but we agree that patient education is important to remember. In addition, the vast majority of patients are able to achieve adequate inspiratory flow with DPIs [10], contrary to what is claimed by the authors based on only one reference from 1992. The authors also suggest that patients treated with DPIs should have a rescue pack of reliever pMDI+spacer at home and they cite their own previous letter stating this same opinion without any data supporting it [11].

We agree that DPIs have not been shown to be suitable for treating life-threatening attacks or to be used in emergency rooms. However, as the authors rightly state, asthma mortality rate is much lower in many countries using a lot of DPIs as compared to higher mortality rates in UK where DPIs are used less (11%) (IQVIA data 2019). Thus, there are no studies showing that patients using DPI relievers are in any greater risk than those relying on pMDI relievers, and real-life asthma outcome on national level is actually better in many countries with higher use of DPIs.

Lastly, the editorial includes a table, “Reducing the environmental impact of inhalers in respiratory care”. This implies that the authors cover all inhalers, although it almost solely focuses on pMDIs. A more suitable title would be “Reducing the environmental impact of pMDIs in respiratory care” and to the “What to do” column “Consider switching to a suitable DPI” would be a justified addition in many of the points. We acknowledge that not all patients, especially young children, are able to use a DPI, but there is significant body of evidence supporting their use in the vast majority of those with asthma.

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