Introduction: Diabetes is a common cause of end-stage kidney disease leading to dialysis or kidney transplantation. Estimated glomerular filtration rate (eGFR) measures kidney function, and differences in the rate (slope) of eGFR decline can be used to assess treatment effects on kidney function over time. In the CREDENCE trial, the sodium glucose co-transporter 2 inhibitor canagliflozin slowed the rate of eGFR decline by 60% compared to placebo in patients with diabetes and chronic kidney disease. This analysis utilized eGFR slopes from CREDENCE to estimate the difference in time to dialysis by treatment arm and estimated the economic value of that delay.
Methods: A linear decline in eGFR and maintenance of stable therapy were assumed for the canagliflozin and placebo arms in CREDENCE. Mean eGFR over time was calculated using acute (baseline to week 3) and chronic (week 3 onward) slopes. Reaching eGFR of 10 ml/min/1.73 m2 was assumed to represent the need for chronic dialysis. The difference in time to dialysis between treatments was calculated. Based on the average duration of dialysis, annual dialysis costs were determined, discounting 2020 US dollars at an inflation rate of 4%.
Results: Following the acute and chronic eGFR slopes, the projected time to dialysis was 22.85 years for canagliflozin and 9.90 years for placebo. Based on 95% confidence intervals from CREDENCE, the model-estimated difference in time to dialysis was 9.27-17.48 years. With a mean baseline participant age of 63 years, the delay in dialysis with canagliflozin would be associated with a reduction in dialysis costs of approximately $170,000 per patient in 2020 dollars.
Conclusion: Using clinical trial data, canagliflozin treatment was projected to delay dialysis by approximately 13 years, which could translate to a substantial cost savings. More precise estimates should be investigated with considerations for nonlinear eGFR slope trajectory, competing risks, and patient characteristics.
Trial registration: ClinicalTrials.gov identifier, NCT02065791.
Keywords: Canagliflozin; Cost of illness; Diabetes mellitus, Type 2; Dialysis; Renal insufficiency, chronic; Sodium glucose co-transporter 2 inhibitors.