Foot Ulcers, Amputation, and Mortality Risk in People With Diabetes

diabetic foot ulcer
“A photograph of a senior woman’s calloused and ulcerated diabetic foot. This patient is dealing with an ulcer on this foot for the second time. High blood sugar affects nerves and blood vessels in the feet, causing them to lose their ability to function properly. Damage to the blood vessels and nerves takes away feeling putting them at a higher risk for trauma. This patient did not feel the first ulcers on the bottom of her foot until it was too late. Extreme infection had set in and antibiotics were ineffective. Parts of the bone in her foot were removed and replaced with steel plates and the top portion of her second toe had to be amputated. The patient has been undergoing treatment for this new ulcer on an outpatient basis. Please see my other images of this patient’s foot to compare the healing progress. Similar Images”
Foot ulcers are a risk in people with either type 1 or type 2 diabetes. Researchers sought to discover whether there was also a relationship between foot ulcers, amputation rates, and other adverse outcomes.

Foot ulcers among people with either type 1 diabetes (T1D) or type 2 diabetes (T2D) were found to occur at an overall rate of 11.2 per 1000 person-years (py) and were associated with a greater risk of amputation or death. These findings, from a national population-based cohort study, was published in Diabetes Care.

Data were sourced from the Scottish Care Information-Diabetes (SCI-Diabetes) database. People (N=233,459) with a diagnosis of diabetes in Scotland by January 1st, 2012, were followed through November 30th, 2017, to assess rates of foot ulceration, clinical outcomes, and various risk factors.

Among individuals who had no foot ulcers at baseline, 4.1% developed ulcers during the follow-up period, and 34.3% of those with a history of foot ulcers developed an additional ulcer. First-time and recurrent foot ulcers occurred at a rate of 7.8 and 97 per 1000 py, respectively, or an overall rate of 11.2 per 1000 py.

During the study period, 10.7% of those with type 1 diabetes had a foot ulcer, 2.1% underwent an amputation, and 9.3% people died. For people with type 2 diabetes, 22.9% of the population had a foot ulcer, 1.1% underwent amputation, and 22.3% died.

For people without a history of foot ulcers, 20.1% developed them, 0.7% underwent amputation, and 19.6% died. Among the cohort with a history of an ulcer, 49.5% developed further ulcers, 9.4% underwent amputation, and 44.5% people died.

Among the cohort of patients with type 1 diabetes who had an amputation or died, amputation occurred among 12.9% of those with no history of ulcer and 33.9% of those with a previous ulcer, respectively.  For type 2 diabetes, the rates were 3.3% and 16.9%, respectively.

Risk for amputation or death was associated with foot ulcer history, previous amputation, male gender (type 1), increasing age, duration of diabetes, end-stage renal failure, ischemic heart disease, peripheral vascular disease, stroke, hypertension, high cholesterol, mental illness, social deprivation, and current/former smoker status (all P <.0001).

In a multivariate model including ulcer history, previous amputation, demographic data, comorbidities, and clinical markers, the risk for amputation or death by 2017 based on ulcer status was higher among patients with type 1 diabetes (adjusted hazard ratio [aHR], 3.39; 95% CI, 3.10-3.71) than type 2 diabetes (aHR, 2.42; 95% CI, 2.36-2.48).

The researchers noted there was a possibility of underestimation of people with foot ulcers in the cohort, which in turn may have resulted in underestimating differences between those recorded with ulcers and those without, especially in terms of death or amputation rates.  

“These national data, with almost 6 years of follow-up, demonstrated a strong association between a history of foot ulcer and amputation or death,” they wrote, noting a number of covariables as well.  “Factors including social deprivation, mental illness, and vascular risk factors need to be addressed in order to reduce premature mortality and amputations for people with diabetes and foot ulcers.”

Reference

Chamberlain RC, Fleetwood K, Wild SH, et al. Foot ulcer and risk of lower limb amputation or death in people with diabetes: a national population-based retrospective cohort study. Diabetes Care. Published online November 15, 2021. doi:10.2337/dc21-1596