Ischaemic diabetic foot : pesrspectives on long-term outcome

Background: Diabetes increases the risk of major amputation 7.6-fold compared to the nondiabetic population in Finland. The risk of amputation is highest in patients with ischaemia and an infection. While efforts are being made for the better prevention and early identification of ulcers, understanding ischaemic ulcers and their treatment, even the most complicated ones, is still necessary. Aim: We aimed to study lower extremity arterial disease (LEAD) and its risk factors in a cohort of type 2 diabetic patients, in addition to investigating the long-term outcome of patients with ischaemic diabetic foot tissue defects according to the mode of treatment. Patients and methods: 130 type 2 diabetic patients, arbitrarily selected from the register of the Helsinki Diabetes Association, were examined at baseline in 1983–1985 and 93 available patients at follow-up an average of 11 years later. Ankle-brachial index (ABI) and serum and urine tests were taken at baseline and ABI again at follow-up (Study I). Data on all free tissue transfer (FTT) operations for diabetic and ischaemic tissue defects of the lower extremities from the beginning of operations in Helsinki in 1989 to 2003 were collected mainly from medical records (Studies II and III). Ninety-nine consecutive patients admitted for angiography due to a suspicion of an ischaemic ulcer were examined and interviewed in 1999 (Study IV). Long-term outcome was analysed mainly based on follow-up data from medical records and, in Study I, based on a new measurement of (ABI). Main results: At baseline, LEAD in type 2 diabetic patients was associated with age, the duration of diabetes, smoking and the urinary albumin excretion rate. The development of new LEAD 11 years later, after the death of the most morbid group of patients, was associated with low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol levels. (Study I.) After combined FTT and vascular reconstruction, the postoperative period was uneventful only in 22% of the patients. The one- and five-year limb salvage rates were 73% and 66%, survival rates 91% and 63%, and amputation-free survival rates 70% and 41%, respectively. Fifty-two percent of the patients were able to ambulate with the preserved leg at two years. Minor ulcer recurrence was observed in 54% of the patients with primary skin healing. (Study II.) In diabetic patients, the amputation-free survival (AFS) rates at one, five and ten years were 90%, 79% and 63%, respectively, among those not requiring revascularisation; 66%, 25% and 18%, respectively, among those who underwent revascularisation; and 50%, 42% and 17%, respectively, among those with uncorrectable ischaemia. Major amputation was associated with smoking, heel ulceration, nephropathy and an ulcer diameter of over 10 cm. (Study III.) Of the patients with ischaemic ulcers, 75% underwent revascularisation, whereas the remaining 25% received conservative treatment. Of patients who underwent revascularisation, 7 had type 1 diabetes and 33 type 2 diabetes, and 31 were non-diabetic. The one-, five- and ten-year AFS rates in the whole cohort were 59%, 31% and 11%, respectively. In multivariate analysis, amputation during the first year of follow-up was significantly associated with unreconstructable ischaemia, uraemia and elevated CRP (c-reactive protein). (Study IV.) Conclusions: A low ABI predicts cardiovascular mortality in diabetic patients with no other signs of cardiovascular disease. Smoking, urine albumin excretion rate, LDL cholesterol and HDL cholesterol are modifiable factors that should be addressed in order to decrease the risk of LEAD. After FTT excellent AFS at five years can be expected in diabetic patients with a native artery open to the foot. Even in the absence of options for revascularisation, moderate AFS can be achieved with careful individual assessment. A large ulcer size and location in the heel were associated with amputation after FTT – in diabetic patients also smoking and uraemia. In patients with ischaemic ulcers, the amputation rate was high during the first two years of follow-up, and mortality was high during the whole follow-up period; the 10-year AFS was 11%. Amputation during the first year was independently associated with elevated CRP, uraemia and uncorrectable ischaemia. Ulcer healing was similar in nondiabetic (65%) and type 2 diabetic patients (67%) with revascularisation.