Abstract 1040: Lower-Limb Amputation in Patients With Type 2 Diabetes Mellitus: Factors Predicting Risk in the FIELD Study
Introduction: The major cause of nontraumatic amputation in the developed world is type 2 diabetes. Lower-limb amputations in type 2 diabetes have profound effects on quality of life and pose a major burden to the economy.
Objective: We explored predictors of lower-limb amputation in the FIELD (Fenofibrate Intervention and Event Lowering in Diabetes) study.
Methods: FIELD followed up 9795 patients with type 2 diabetes mellitus who were randomized to fenofibrate 200 mg/day or matching placebo for 5 years and recorded amputation events at approximately 6-monthly intervals. Clinicians masked to treatment allocation adjudicated amputations as minor or major (below or above the ankle) and also based on large-vessel disease in the limb to distinguish predominantly microvascular disease from large-artery atherosclerosis. Multivariable proportional hazards regression was used to develop risk models for the first on-study amputation and for predominantly microvascular amputations (minor amputations with no associated large-vessel disease).
Results: A total of 190 amputations occured in 115 patients. The most significant predictors of a first on-study amputation were prior skin ulcer or amputation (hazard ratio [HR] 5.6), neuropathy (HR 2.7), peripheral vascular disease (HR 2.5), age (HR 1.7 per 10 years older) and height (HR 1.6 per 10 cm taller) (all P<0.001). Other significant predictors included smoking, albuminuria, HBA1c, retinopathy, and PTCA. The strongest predictors of microvascular amputations were similar: previous nontraumatic amputation or diabetic skin ulcer (HR 7.5), neuropathy (HR 4.5), height (HR 2.2 for each 10 cm increase), macroalbuminuria (HR 2.8), and diabetes duration (HR 1.3 for each additional 5 years with diabetes). Lipid variables (total cholesterol, LDL-c, HDL-c, triglyceride) were not significant in predicting future amputation risk and did not remain in any risk models.
Conclusion: Both macrovascular and microvascular risk markers predicted on-study amputations. Height, independent of neuropathy, also predicted amputations. Identifying patients at high risk of amputation is now possible, for earlier treatment of their modifiable risk factors to prevent this debilitating outcome.