Disclosures: Dr. Val Stoynova and Dr. Celia Culley both sit on the Sustainable Inhaler National Advisory Committee and have received a small associated stipend from a not-for-profit organization with no pharmaceutical ties for their involvement.
Mitigating potential bias: Only published trial data is presented and all recommendations are consistent with current published GINA, CTS, and BTS guidelines on asthma therapy.
What I did before
Asthma is one of the most common chronic diseases, affecting nearly 3.8 million Canadians.1 Inhaler therapy is the backbone of treatment. In North America, the market is dominated by metered dose inhalers2 (MDIs) so much so that a Google image search for “inhaler” will return almost exclusively images of MDIs.
My own practice was based on MDIs; it’s what I learnt during training and it’s what patients requested. Physician knowledge (what I’ve been taught) and bias (what I unquestionably assume to be true) significantly contribute to the type of inhaler prescribed.3
What changed my practice
There is no denying the ongoing climate crisis in BC and its disproportionate effect on vulnerable populations. In the last year alone, we had the third worst forest fire season on record,4 the heat dome took 619 lives5 and diluvian floods disrupted access to our largest metropolitan hubs.6
This series of climate disasters has led to a fundamental re-examination of how my practice is contributing to the climate emergency and how I can best change with the times.
Little did I know, the MDIs I favoured are major contributors to greenhouse gas (GHG) emissions. Pressurized MDIs contain a hydrofluoroalkane (HFA) propellant which provides the force to expel the medication from the cannister with each actuation. HFAs are potent greenhouse gases, the most common of which (HFA134a) is 1,300 times more potent than CO2.7
While each individual actuation is negligeable in terms of GHG release, the cumulative effect is staggering: MDIs alone account for 3.5% of the UK’s National Health Service’s entire carbon footprint.8 Globally, 800 million MDIs are produced worldwide each year creating over 18 billion kilos of CO2 equivalents.9
Decreasing inhaler-related GHG emissions through rational, evidence-based deprescribing and through transition to low-carbon alternatives has been gaining momentum internationally10 and in the lay media.11
Regarding deprescribing, one third of Canadians labelled with asthma don’t actually have asthma on objective testing.12 Nearly 80% of Canadians with negative spirometry remain on inhaler therapy.13 The BC Choosing Wisely campaign advises against starting inhalers in adult patients without a confirmed diagnosis of asthma on spirometry, pulmonary function test, or methacholine challenge testing. A misdiagnosis of asthma can lead to missing alternative diagnoses, unnecessary medication side effects, and associated costs.14
Regarding alternatives, dry-powder inhalers (DPIs) are safe, effective, low-cost, low-carbon inhalers that are widely available in Canada.16 DPIs differ from MDIs in that the patient’s inspiratory capacity is responsible for drug delivery into the lung rather than a propellant agent.
The environmental impact of changing to DPIs is astounding. Switching a single patient’s asthma maintenance and rescue MDI inhalers to DPI equivalents reduces the carbon footprint of their treatment by 425kg CO2e per year.15 This is nearly as much carbon reduction as adopting a vegan diet.15
What I do now
When I choose to prescribe an inhaler, I remain mindful of the carbon impact of my prescribing choices. I do so by asking 4 questions each time I assess respiratory disease in the clinic:
1) Does my patient actually need an inhaler?
I review prior spirometry, pulmonary function testing, or methacholine challenge testing for confirmation of reactive airway disease prior to prescribing, and I order these tests if necessary.
2) Does my patient have the right active ingredient? The right dose?
In line with current GINA guidelines13 and Canadian Thoracic Society guidelines,16 I favour inhaled corticosteroid (ICS) as maintenance plus short-acting beta-agonist (SABA) as reliever. They also recommend combination long-acting beta-agonist (LABA)/ICS as first line for both maintenance and rescue therapy in mild asthma.13,16
All single-agent ICS inhalers are covered as first line treatment in BC, regardless of their delivery mechanism. However, Pharmacare only covers ICS/LABA combination inhalers if ICS- monotherapy maintenance failed. Regardless of drug class, DPIs are often the less expensive option for patients when considering the cost per dose.
|Example of moderate intensity ICS prescription||Cost of inhaler*||Number of actuations per device||Cost per dose**|
|Fluticasone MDI 125 mcg 1 inh BID||$66.63||120||$0.56/dose|
|Budesonide DPI 200 mcg 1 inh BID||$91.17||200||$0.46/dose|
|Example of moderate intensity ICS/LABA prescription||Cost of inhaler***||Number of actuations per device||Cost per dose**|
|Fluticasone/Salmeterol MDI 125/25 mcg 1 inh BID||$140.82||120||$1.17/dose|
|Budesonide/Formoterol DPI 200/6 mcg 1 inh BID||$115.86||120||$0.97/dose|
|Example of SABA prescription||Cost of inhaler*||Number of actuations per device||Cost per dose**|
|Salbutamol MDI 100 mcg 2 inh QID PRN||$18.45||200||$0.19/dose (2 inh)|
|Terbutaline DPI 0.5 mg 1 inh QID PRN||$21.38||100||$0.21/dose|
*excludes dispensing fee
**cost retrieved from drugsearch.ca
***excludes dispensing fee, assumes no SA coverage
I review my patient’s asthma control at each visit and increase maintenance dosing, or change to combination LABA/ICS, if they are relying too heavily on a SABA (i.e. using their rescue inhaler more than twice a week).16
3) Does my patient have the right delivery mechanism or device?
Several studies have demonstrated that switching from an MDI to a DPI does not decrease clinical effectiveness.17 In fact, there is both clinical improvement and higher patient satisfaction when this change is done for environmental reasons.18 The most recent British Thoracic Society guidelines even recommend preferentially switching from an MDI to a non-propellant device.19
However, caution must be taken at this stage. A patient needs to be able to generate sufficient inspiratory flow to trigger a DPI actuation. The necessary minimal flow rate to overcome the internal device resistance is 30mL/min for the majority of DPIs, although it is as low as 20mL/min for certain devices.20 By comparison, the recommended flow rate for an MDI is 20 to 60mL/min; this may be somewhat lower if a spacer is used.20 In a recent study, over 90% of adult patients with asthma using DPIs were able to achieve a flow rate of greater than 30mL/min, meaning a small but significant proportion of patients would not get adequate drug delivery with DPIs with female sex and age greater than 70 being independent risk factors.21 (Interestingly, in the same study, a third of adult patients using MDIs were not generating correct inspiratory flow for their MDIs either; they were breathing in too quickly.)21
4) Is my patient ready to switch?
When I consider changing my patient’s inhalers, I start by discussing the environmental impact of their device; nearly 80% of patients consider the environmental impact of asthma treatment to be important.22 I stress the importance of shared decision-making around inhalers as a way to empower my patient and improve their compliance and their health outcomes.23 Conversely, not all patients are ready to switch and non-consensual changes in inhaler therapy lead to worse outcomes.24
In summary, I have changed my practice to optimize patient care and planetary health by considering the climate impact of my prescribing choices while continuing to provide high-quality, evidence-based, lower cost, patient-centred asthma care.
- If you are interested in learning more about decreasing the carbon footprint of inhalers in your practice, please visit cascadescanada.ca for patient- and provider-facing resources.
- If you are interested in learning more about the different inhaler types available in Canada and how to use them, please visit lung.ca for patient- and provider-facing instructional videos.
- Asthma Canada. Annual asthma survey report: a snapshot of asthma in Canada. Asthma Canada, 2020. Accessed Apr 7, 2022. (View)
- Intergovermental Panel on Climate Change. Medical Aerosols in IPCC/TEAP Special Report: Safeguarding the ozone layer and the global climate system. IPCC. September 2007. Accessed February 2, 2022. (View)
- Lavorini F, Corrigan CJ, Barnes PJ, et al. Retail sales of inhalation devices in European countries: So much for a global policy. Resp Med. 2011;105(7),1099-1103. DOI: 10.1016/j.rmed.2011.03.012. (View)
- Kulkarni A. A look back at the 2021 B.C. wildfire season. CBC News. Published Oct 4, 2021. Accessed Feb 10, 2022. (View)
- Government of British Columbia. Extreme Heat and Human Mortality: A Review of Heat-Related Deaths in B.C. in Summer 2021. Report to the Chief Coroner of British Columbia. Release Date: June 7, 2022. Accessed June 28, 2022. (View)
- Judd A, Michaels K. Flooding and mudslides in C. wreak havoc on highways, forcing evacuations. Global News. Published Nov 15, 2021. Accessed Feb 10, 2022. (View)
- Intergovernmental Panel on Climate Change. AR4 climate change 2007: the physical science basis. IPCC, 2007. Accessed April 7, 2022. (View)
- Tennison I, Roschnik S, Ashby B, et al. Health care’s response to climate change: a carbon footprint assessment of the NHS in England. Lancet Planet Health 2021;5(2):e84-e92. DOI: 10.1016/S2542-5196(20)30271-0. (View)
- Ohnishi K, Tope H, Zhang J. Montreal Protocol on Substances that Deplete the Ozone Layer: 2018 Report of the Medical and Chemical Technical Options Committee: 2018 Assessment Report. Medical and Technical Options Committee, Dec 2018. Accessed Apr 7, 2022. (View)
- Gill S. A greener NHS – reducing the environmental impact of asthma inhalers. Academic Health Science Network: North East and North Cumbria, Feb 2022. Accessed Apr 7, 2022. (View)
- Pelley L. Swap your inhaler, skip the laughing gas: how patients can help curb the health-care emissions. CBC News. Published Nov 3, 2021. Accessed Jan 10, 2022. (View)
- Aaron SD, Aaron SD, Vandemheen KL, FitzGerald JM, Ainslie M. Reevaluation of diagnosis in adults with physician-diagnosed asthma. JAMA: the Journal of the American Medical Association. 01/2017;317(3):269-279. DOI: 10.1001/jama.2016.19627. (Request from CPSBC or view with UBC)
- Global Initiative for Asthma. Global strategy for asthma management and prevention. 2021. Accessed Feb 28, 2022. (View)
- Canadian Thoracic Society. Seven tests and treatments to question. Choosing Wisely Canada. Published March 2021. Accessed April 2022. (View)
- Janson C, Henderson R, Lofdahl M, Hedberg M, Sharma R, Wilkinson AJK. Carbon footprint impact of the choice of inhalers for asthma and COPD. Thorax. 2020; 75(1), 82-4. DOI:10.1136/thoraxjnl-2019-213744 (View)
- Yang CL, Hicks EA, Mitchel P et al. Canadian Thoracic Society 2021 Guideline Update: Diagnosis and management of asthma in preschoolers, children and adults. Can J Respir Crit Care Sleep Med 2021;5(6):348-61. DOI: 10.1080/24745332.2021.1945887 (View)
- Price DB, Roman-Rodriguez RB, McQueen RB, et al. Inhaler errors in the CRITIKAL study: type, frequency, and associated with asthma outcomes. J Allergy Clin Immunol Pract 2017;5(4):1071-1081.e9. DOI: 10.1016/j.jaip.2017.01.004. (Request from CPSBC or view with UBC)
- Gálffy G, Szilasi M, Tamási L. P227 Clinical effectiveness, health-related quality of life and patient satisfaction after switch from metered-dose inhaler to easyhaler dry powder inhaler in patients with asthma and COPD; a real-life study. Thorax 2019;74(suppl 2):A212-3. DOI: 1136/thorax-2019-BTSabstracts2019.370. (Request from CPSBC or view with UBC)
- Scottish Intercollegiate Guidelines Network and British Thoracic Society. BTS/SIGN British guideline on the management of asthma: a national clinical guideline. SIGN and BTS Jul 2019. Accessed Feb 2, 2022. (View)
- Haidl P, Heindl S, Siemon K, Bernacka M, Cloes RM. Inhalation device requirements for patients’ inhalation maneuvres. Respir Med 2016;118:65-75. DOI: 10.1016/j.rmed.2016.07.013 (View)
- Haughney J, Lee AJ, Mcnight E, Pertsovskaya I, O’Driscoll M, Usmani OS. Peak inspiratory flow measured at different inhaler resistances in patients with asthma. J Allergy Clin Immunol Pract 2021;9(2):890-896. DOI: 10.1016/j.jaip.2020.09.026 (View)
- Liew KL, Wilkinson A. P280 How do we choose inhalers? Patient and physician perspectives on environmental, financial and ease-of-use factors. Thorax. 2017; 72(3), A235- 236. Doi: 10.1136/thoraxjnl-2017-210983.422 (View)
- Kaplan A, Price D. Matching inhaler devices with patients: The role of the primary care physician. Can Respir J 2018;2018:9473051. Published May 23, 2018. (View)
- Gilbert I, Wada K, Burudpakdee C, Ghai C, Tan L. The impact of a forced non-medical switch of inhaled respiratory medication among patients with asthma or chronic obstructive pulmonary disease: A patient survey on experience with switch, therapy satisfaction, and disease control. Patient Prefer Adherence 2020;14:1463-75. Doi: 10.2147/PPA.S242215 (View)