Impact of carbon footprint information on inhaler prescribing intentions by general practitioners: an online factorial randomised experiment

Directly after randomisation, all participants will receive an online hypothetical scenario for them to read through. This is part of the online survey administered through Qualtrics and is estimated to take 2-5 minutes to read. The interventions are delivered by the study researchers through Qualtrics, each participant will be randomised to one of four interventions (2x2 factorial) or a control scenario. The randomised intervention (or control) will be delivered once only to each participant and will occur online. Qualtrics will record how much time participants spend on the page, which we can use as a proxy to monitor adherence (i.e. if participants had enough time to read through the allocated scenario). there is no "back" button included in the online survey, hence, participants cannot go back to be re-allocated to a different scenario. Our baseline clinical scenario reflects a usual GP consultation for a hypothetical, adult middle-aged female with mild to moderate but poorly controlled asthma. Participants will be asked to imagine that for this patient, they had previously prescribed a dry powder inhaler (DPI), low-dose inhaled corticosteroid (ICS)-containing preventer and a pressurised metered dose (pMDI) short-acting beta2-agonist (SABA) reliever, and that she reported regular use of this reliever without a spacer and irregular use of the preventer inhaler. They are then informed that they decide to recommend the patient trial maintenance and reliever therapy (MART) with an anti-inflammatory reliever (ICS-formoterol inhaler), as per the newly revised Australian Asthma Guidelines. They explain this approach to the patient, check the patient’s inhaler technique is adequate for both types of devices, establish that both inhaler types incur the same out-of-pocket cost to the patient and that she has no preference for inhaler type but is asking for the GP’s recommendation. The four possible intervention arms that participants can be randomised to are: A. Collective impact / with graphic (factor 2, level 0): additional information on differences in environmental impacts from prescribing different types of inhalers to all similar patients from five GPs over one year with graphic display: additional information on the carbon footprint of one DPI versus one pMDI, the carbon emission savings in kg CO2e emissions for prescribing a DPI instead of pMDI for 200 similar patients (5 GPs with 40 patients each) over one year, and the private car journey distance this is equivalent to. Plus an additional graphic display of the annual potential differences in carbon footprint. This comprises bar charts comparing the carbon savings in CO2e emissions to the impact of six other potential emissions-reducing behaviour changes to give participants some perspective around the meaning of the carbon footprint. B. Single impact/ with graphic (factor 2, level 1): additional information on differences in environmental impacts from prescribing different types of inhalers to the one patient with graphic display: additional information on the carbon footprint of one DPI versus one pMDI, the carbon emission savings in kg CO2e emissions for prescribing a DPI instead of pMDI for one patient over one year, and the private car journey distance this is equivalent to. Plus an additional graphic display of the annual potential differences in carbon footprint. This comprises bar charts comparing the carbon savings in CO2e emissions to the impact of six other potential emissions-reducing behaviour changes to give participants some perspective around the meaning of the carbon footprint. C. Collective impact / no graphic (factor 1, level 1): additional information on differences in environmental impacts from prescribing different types of inhalers to all similar patients from five GPs over one year without graphic display: additional information on the carbon footprint of one DPI versus one pMDI, the carbon emission savings in kg CO2e emissions for prescribing a DPI instead of pMDI for 200 similar patients (5 GPs with 40 patients each) over one year, and the private car journey distance this is equivalent to. D. Single impact / no graphic (factor 1, level 0): additional information on differences in environmental impacts from prescribing different types of inhalers to the one patient without graphic display: additional information on the carbon footprint of one DPI versus one pMDI, the carbon emission savings in kg CO2e emissions for prescribing a DPI instead of pMDI for one patient over one year, and the private car journey distance this is equivalent to.