Clinician and health service interventions to reduce the greenhouse gas emissions generated by healthcare: a systematic review.

objectiveTo synthesise the available evidence on the effects of interventions designed to improve the delivery of healthcare that reduces the greenhouse gas (GHG) emissions of healthcare.

designSystematic review and structured synthesis. SEARCH SOURCES: Cochrane Central Register of Controlled Trials, PubMed, Web of Science and Embase from inception to 3 May 2023. SELECTION CRITERIA: Randomised, quasi-randomised and non-randomised controlled trials, interrupted time series and controlled or uncontrolled before-after studies that assessed interventions primarily designed to improve the delivery of healthcare that reduces the GHG emissions of healthcare initiated by clinicians or healthcare services within any setting.

main outcome measuresPrimary outcome was GHG emissions. Secondary outcomes were financial costs, effectiveness, harms, patient-relevant outcomes, engagement and acceptability. DATA COLLECTION AND ANALYSIS: Paired authors independently selected studies for inclusion, extracted data, and assessed risk of bias using a modified checklist for observational studies and the certainty of the evidence using Grades of Recommendation, Assessment, Development and Evaluation. Data could not be pooled because of clinical and methodological heterogeneity, so we synthesised results in a structured summary of intervention effects with vote counting based on direction of effect.

results21 observational studies were included. Interventions targeted delivery of anaesthesia (12 of 21), waste/recycling (5 of 21), unnecessary test requests (3 of 21) and energy (1 of 21). The primary intervention type was clinician education. Most (20 of 21) studies were judged at unclear or high risk of bias for at least one criterion. Most studies reported effect estimates favouring the intervention (GHG emissions 17 of 18, costs 13 of 15, effectiveness 18 of 20, harms 1 of 1 and staff acceptability 1 of 1 studies), but the evidence is very uncertain for all outcomes (downgraded predominantly for observational study design and risk of bias). No studies reported patient-relevant outcomes other than death or engagement with the intervention.

conclusionsInterventions designed to improve the delivery of healthcare that reduces GHG emissions may reduce GHG emissions and costs, reduce anaesthesia use, waste and unnecessary testing, be acceptable to staff and have little to no effect on energy use or unintended harms, but the evidence is very uncertain. Rigorous studies that measure GHG emissions using gold-standard life cycle assessment are needed as well as studies in more diverse areas of healthcare. It is also important that future interventions to reduce GHG emissions evaluate the effect on beneficial and harmful patient outcomes. PROSPERO REGISTRATION NUMBER: CRD42022309428.