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

Abstract

Aims/hypothesis: Our 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.

Methods: Overall, 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.

Results: The 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/interpretation: In 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.

Keywords: Amputation; Diabetes; Foot; Mortality; Ulcer.

Fig. 1

Kaplan–Meier survival curve showing amputation-free survival in people identified as having high-risk of foot ulceration. The healed ulcer group had the lowest amputation-free survival rate compared with the group with no previous or current ulcer and the active ulcer group. Red line, no ulcer; green line, active ulcer; blue line, healed ulcer