Amputation-free survival in 17,353 people at high risk for foot ulceration in diabetes: a national observational study

Thenmalar Vadiveloo,Sarah Wild,Rory Mccrimmon,Helen C Colhoun,Graham P Leese,William Jeffcoate,Stuart Mcgurnaghan,Peter T Donnan

doi:10.1007/s00125-018-4723-y

Abstract

Aims/hypothesisOur aim was to investigate amputation-free survival in people at high risk for foot ulceration in diabetes (‘high-risk foot’), and to compare different subcategories of high-risk foot.MethodsOverall, 17,353 people with diabetes and high-risk foot from January 2008 to December 2011 were identified from the Scotland-wide diabetes register (Scottish Care Information-Diabetes: N = 247,278). Participants were followed-up for up to 2 years from baseline and were categorised into three groups: (1) those with no previous ulcer, (2) those with an active ulcer or (3) those with a healed previous ulcer. Participants with prior minor or major amputation were excluded. Accelerated failure time models were used to compare amputation-free survival up to 2 years between the three exposure groups.ResultsThe 2 year amputation-free survival rate in all people with diabetes with high-risk foot was 84.5%. In this study group, 270 people (10.0%) had an amputation and 2424 (90.0%) died during the 2 year follow-up period. People who had active and healed previous ulcers at baseline had significantly lower 2 year amputation-free survival compared with those who had no previous ulcer (both p < 0.0001). The percentage of people who died within 2 years for those with healed ulcer, active ulcer or no baseline ulcer was 22.8%, 16% and 12.1%, respectively.Conclusions/interpretationIn people judged to be at high risk of foot ulceration, the risk of death was up to nine times the risk of amputation. Death rates were higher for people with diabetes who had healed ulcers than for those with active ulcers. However, people with active ulcers had the highest risk of amputation.

Highlights

Diabetic foot ulcers and amputations are devastating and much feared complications of diabetes
There were a total of 17,459 people with diabetes across Scotland who were identified with high-risk of feet ulceration from January 2008 to December 2011
People with diabetes and previously healed ulcers had a worse outcome than people with an active ulcer, who in turn had a worse outcome than people with diabetes and no previous foot ulcer

Summary

Introduction

Diabetic foot ulcers and amputations are devastating and much feared complications of diabetes. Between 15% and 34% of people with diabetes develop a foot ulcer during their lifetime, with more than half acquiring infections [1] that may result in lower extremity amputations causing disability, extensive periods of hospitalisation, and premature mortality [2, 3]. Clinical epidemiology studies suggest that foot ulcers precede around 85% of non-traumatic lower extremity amputations in individuals with diabetes [8] and ulcer prevention is important. Previous studies have reported that apart from severity of ulcer, age [9], low socioeconomic status, smoking [10, 11], sex [12], renal impairment [13], ischaemic heart disease, diabetic neuropathy [14], glucose levels [15] and peripheral arterial disease [16] are some of the important factors associated with the risk of amputation. Most studies have identified a history of a previous ulcer as the strongest predictor of future ulcers [17,18,19,20, 22], a global risk score is a more sensitive way of predicting foot ulceration than using any individual risk score [23]

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