Mortality and Major Amputation in Patients With Diabetes-Related Foot Ulcers and Chronic Renal Disease

This study examines mortality and major limb amputation (MLA) in patients with diabetes-related foot ulcers (DRFU) and renal impairment.

All patients admitted for management of a DRFU between October 2016 and September 2021 at a tertiary hospital in Aotearoa New Zealand (AoNZ) were included and followed until September 2024. Patients were grouped according to renal function: intact renal function; renal impairment with baseline creatinine greater than 150 μmol/L; and requirement for dialysis. Rate of mortality and rate of major limb amputation (MLA) were calculated at 1, 3, 5, and 7 years. Kaplan-Meier probability estimates were utilised to compare the survival and amputation-free survival of the dialysis cohort to the non-dialysis cohort. R Version 4.4.1 and Python were used for statistical analyses.

Seven hundred seventy-two patients were admitted for management of a DRFU, of whom 431 (59%) had intact renal function, 160 (27%) had impaired renal function, and 136 (18.7%) required dialysis. The median follow-up was 19.3 months. Patients in the dialysis cohort were younger, median age 64 years, compared to 70 years in the non-dialysis cohort. Mortality rates were significantly higher in the dialysis cohort at 1 (33.8% vs. 17.6%), 3 (58.8% vs. 37.9%), 5 (69.9% vs. 50.5%) and 7 years (87.6% vs. 64.4%) (p < 0.001) with median survival time of 27.1 months compared to 47.7 months (p < 0.001). The MLA rate was significantly higher in the dialysis cohort at each time point: 1 year (31.6% vs. 3.2%), 3 years (36% vs. 7.5%), 5 years (40.5% vs. 12.4%), and 7 years (42.6% vs. 19.6%) (p < 0.001). There was no difference in outcomes between those with renal impairment and intact renal function cohorts, and no difference by ethnicity.

AoNZ patients with a DRFU and ESRD on dialysis have significantly higher mortality and major amputation rates, even within the first year of a new admission with a DFRU. Limited life expectancy should be considered when planning interventions for these patients.