Foot Ulcer and Risk of Lower Limb Amputation or Death in People With Diabetes: A National Population-Based Retrospective Cohort Study
To describe incidence of foot ulceration and amputation free survival associated with foot ulceration status in a national population-based cohort study of people with diabetes.
Research Design and Methods
The study population included 233,459 people with diabetes who were alive in Scotland on 1st January 2012 identified from the national population-based register (national prevalence 4.9%). Characteristics of patients identified from linked hospital and mortality records during follow-up to the end of November 2017 were compared by outcome. Cox regression was used to assess the association between history of foot ulcer and amputation free survival.
The population included 23,395 people with type-1 diabetes and 210,064 people with type-2 diabetes. In total there were 13,093 (5.6%) people with a previous foot ulceration, 9,023 people developed a first ulcer, 48,995 died and 2,866 underwent minor or major amputation during follow-up. Overall incidence of first time foot ulcers was 7.8 per 1000 person years (95% CI: 7.6-7.9) and 11.2 (11.0-11.4) for any ulcer. Risk factors for reduced amputation-free survival included social deprivation, mental illness and being underweight in addition to conventional cardiovascular risk factors. Adjusted hazards ratios (95% CI) were 2.09 (1.89-2.31) for type-1 diabetes and 1.65 (1.60-1.70) for type-2 diabetes.
The overall incidence of foot ulceration in a population-based study of people with diabetes was 11.2 per 1000 person years. Foot ulceration is associated with lower amputation-free survival, a potential measure of effectiveness of care among people with diabetes. Mental illness and social deprivation are also highlighted as risk factors.