The potential for reducing greenhouse gas emissions through disease prevention: a secondary analysis of data from the CREDENCE trial

Background: The health-care sector is responsible for 5·2% of global emissions, however, little data exist regarding the environmental impact of disease management strategies. SGLT2 inhibitors are now widely used to reduce the risk of hospital admission and kidney failure in people with type 2 diabetes and chronic kidney disease. This study aimed to estimate the impact of SGLT2 inhibitors on greenhouse gas emissions using data from the CREDENCE trial.

Methods: For this modelling analysis, we used data from the randomised, double-blind, placebo-controlled, CREDENCE trial, which compared the effect of canagliflozin versus placebo on kidney and cardiovascular outcomes in patients with type 2 diabetes and albuminuric chronic kidney disease. For this secondary analysis, we included all participants randomly assigned to canagliflozin or placebo at baseline in the CREDENCE trial. Data on greenhouse gas emissions resulting from hospital inpatient days, maintenance dialysis therapy, and SGLT2 inhibitor tablet production were derived from published reports and used to model greenhouse gas emissions from total number of hospital inpatient days, total number of days of maintenance dialysis therapy, and from SGLT2 inhibitor treatment over the course of the CREDENCE trial. We compared greenhouse gas emission estimates for participants in the canagliflozin group and placebo group of the CREDENCE trial. We used bootstrapping analyses to calculate uncertainty estimates and permutation tests to generate p values for the difference in number of days on dialysis and inpatient bed days between treatment groups.

Findings: 4401 participants who were randomly assigned to the canagliflozin (n=2202) or placebo group (n=2199) were included in the secondary analyses. During a median follow-up of 2·62 years (IQR 0·02 to 4·53), SGLT2 inhibitor production for 2202 participants resulted in greenhouse gas emissions of 63 tonnes of CO₂ equivalent (CO₂e; 95% CI 62 to 64). The total number of inpatient bed days was 17 002 days in the placebo group versus 13 672 days in the canagliflozin group; the 3330 fewer inpatient days (95% CI 1037 to 5686; p=0·042) with SGLT2 inhibitor treatment equated to a reduction of approximately 126 tonnes of CO₂e (95% CI 39 to 216). Participants in the placebo group required 24 877 days of maintenance dialysis compared with 16 605 days in the treatment group; 8272 fewer days of dialysis ( -168 to 16 755; p=0·16), equated to a reduction of 161 tonnes of CO₂e (-3 to 327). Overall, mean greenhouse gas emissions per-participant-year were reduced from 196 kg of CO₂e per-participant-year to 157 kg of CO₂e per-participant-year.

Interpretation: The addition of an SGLT2 inhibitor to routine therapy for people with type 2 diabetes and chronic kidney disease has the potential to reduce greenhouse gas emissions through the prevention of hospital admissions and need for dialysis.

Funding: None.