Aim: Diabetic foot ulcers are associated with an increased risk of death. We evaluated whether ulcer severity at presentation predicts mortality.
Methods: Patients from a national, retrospective, cohort of veterans with type 2 diabetes who developed incident diabetic foot ulcers between January 1, 2006 and September 1, 2010, were followed until death or the end of the study period, January 1, 2012. Ulcers were characterized as early stage, osteomyelitis, or gangrene at presentation. Cox proportional hazard regression identified independent predictors of death, controlling for comorbidities, laboratory parameters, and healthcare utilization.
Results: 66,323 veterans were included in the cohort and followed for a mean of 27.7 months: 1-, 2-, and 5-year survival rates were 80.80%, 69.01% and 28.64%, respectively. Compared to early stage ulcers, gangrene was associated with an increased risk of mortality (HR 1.70, 95% CI 1.57–1.83, p b 0.001). The magnitude of this effect was greater than diagnosed vascular disease, i.e., coronary artery disease, peripheral arterial disease, or stroke.
Conclusion: Initial diabetic foot ulcer severity is a more significant predictor of subsequent mortality than coronary artery disease, peripheral arterial disease, or stroke. Unrecognized or under-estimated vascular disease and/or sepsis secondary to gangrene should be explored as possible causal explanations.
Half of patients who develop a diabetic foot ulcer will die within five years (Boyko, Ahroni, Smith, & Davignon, 1996; Martins-Mendes et al., 2014; Walsh, Hoffstad, Sullivan, & Margolis, 2015). Most often, they succumb to vascular complications, namely heart attacks and strokes (Boyko et al., 1996; Morbach et al., 2012; Moulik, Mtonga, & Gill, 2003). However, recent cohort studies concluded that foot ulcers alone remain a significant independent predictor of mortality, even after adjusting for known vascular disease and other comorbidities (Martins-Mendes et al., 2014; Walsh et al., 2015). We hypothesized that the subgroup of patients with severe diabetic foot ulcers, namely those complicated by osteomyelitis or gangrene, would have the highest associated mortality among patients with diabetic foot ulcers. This was based upon the finding that severe ulcers are associated with increased morbidity, especially major (above ankle) amputation (Helmer et al., 2011; Peters et al., 2001; Prompers, Schaper, et al., 2008). Therefore, our aim was to determine whether the severity of incident diabetic foot ulcers at presentation predicts subsequent mortality