Objective: To evaluate the incidence and risk factors of lower extremity amputation among inpatients with diabetic foot.
Methods: For this retrospective study, a total of 685 inpatients with diabetic foot (Wagner grade 1-5) admitted at a multi-disciplinary Diabetic Foot Care Center, West China Hospital, Sichuan University during January 1, 2005 and June 30, 2011. The data of each patient including clinical information, laboratory results and final outcome were collected and analyzed. They were divided into non-amputated and amputated groups. And the latter included minor and major amputation groups according to amputation site.
Results: The overall amputation rate was 11.4% in diabetic foot inpatients. The incidences of minor amputation and major amputation were 5.4% and 6.0% respectively. 17.9% of amputated patients experienced a second amputation. The amputated patients had a longer hospitalized stay, higher counts of white blood cells and neutrophils, greater HbA1c and lower serum levels of hemoglobin and albumin than the non-amputation patients (P < 0.05). The prevalence of diabetic peripheral neuropathy was significantly higher in the amputation group than that in the non-amputation group (P < 0.05). However, no difference existed between the minor and major amputation groups (P > 0.05). Ankle brachial index (ABI) in the amputation group was significantly lower than that in the non-amputation group (0.41 ± 0.25 vs 0.91 ± 0.36, P < 0.01). Minor and major amputation inpatients had similar ABI (0.43 ± 0.24 vs 0.39 ± 0.26, P = 0.087). Ordinal regression showed that HbA1c (P = 0.015), ABI (P = 0.016), history of amputation (P < 0.01) and Wagner grade of diabetic foot (P < 0.01) were the independent risk factors of amputation.
Conclusions: Diabetic foot inpatients have a higher rate of lower extremity amputation. The risk factors of amputation include HbA1c, ABI, history of amputation and Wagner grade of diabetic foot. And diabetic peripheral neuropathy, ischemia of lower limbs (especially peripheral arterial diseases below knees), infection and nutritional state are closely associated with amputation of diabetic foot inpatients.