Mortality in Patients with Diabetic Foot Ulcers: Causes, Risk Factors, and Their Association with Evolution and Severity of Ulcer

Abstract

Background: This study reviews the mortality of patients with diabetic foot ulcers (DFU) from the first consultation with a Multidisciplinary Diabetic Foot Team (MDFT) and analyzes the main cause of death, as well as the relevant clinical factors associated with survival. Methods: Data of 338 consecutive patients referred to the MDFT center for a new DFU during the 2008-2014 period were analyzed. Follow-up: until death or until 30 April 2020, for up to 12.2 years. Results: Clinical characteristics: median age was 71 years, 92.9% had type 2 diabetes, and about 50% had micro-macrovascular complications. Ulcer characteristics: Wagner grade 1-2 (82.3%), ischemic (49.2%), and infected ulcers (56.2%). During follow-up, 201 patients died (59.5%), 110 (54.7%) due to cardiovascular disease. Kaplan-Meier curves estimated a reduction in survival of 60% with a 95% confidence interval (95% CI), (54.7-65.3) at 5 years. Cox regression analysis adjusted to a multivariate model showed the following associations with mortality, with hazard ratios (HRs) (95% CI): age, 1.07 (1.05-1.08); HbA1c value < 7% (53 mmol/mol), 1.43 (1.02-2.0); active smoking, 1.59 (1.02-2.47); ischemic heart or cerebrovascular disease, 1.55 (1.15-2.11); chronic kidney disease, 1.86 (1.37-2.53); and ulcer severity (SINBAD system) 1.12 (1.02-1.26). Conclusion: Patients with a history of DFU have high mortality. Two less known predictors of mortality were identified: HbA1c value < 7% (53 mmol/mol) and ulcer severity.

Keywords: SINBAD system; diabetic foot ulcers; diabetic foot unit; morbidity; mortality; reulceration; ulcer severity.

Figure 1

Survival analysis of the 338 patients with diabetic foot ulcers (DFU) from their first consultation at the MDFT center. The Kaplan—Meier curve shows the estimated 5-year survival rate.

Figure 2

Kaplan—Meier curves for survival. (A): Survival by HbA1c in total cohort (n = 334, 4 subjects no data). (B): Survival by SINBAD score system (n = 338). (C): Survival by revascularization in patients with ischemic lesion (n = 167). (D): Survival by reulceration in patients after the resolution of the DFU and without major amputation (n = 287).