Testing the sympathetic nervous system of the foot has a high predictive value for early amputation in patients with diabetes with a neuroischemic ulcer

Objective There is evidence from the literature that dysfunctionality of the sympathetic nervous system of the foot with subsequent loss of local autoregulation could be a predictor of early amputation in patients with diabetes with a neuroischemic ulcer. To confirm this we tested the functionality of the sympathetic nervous system in the foot in a consecutive group of 31 patients with diabetes with critical limb ischemia and non-healing neuroischemic ulcer. Research design and methods Prospective cohort with retrospective analysis after 12 months of routinely acquired clinical data. All patients in the study group underwent angiography of the foot as part of a routine angioplasty procedure. Primary study endpoint was lower extremity amputation-free survival at 12 months. Because of the study design no other endpoints could be analyzed. The functionality of the sympathetic nervous system was tested with perfusion angiography. Results Thirty-one patients were followed for 12 months. The Capillary Resistance Index (CRI) was used to measure the response of the sympathetic nervous system. CRI >= 0.9 is the cut-off point for a non-responsive sympathetic nervous system. All patients (n=11) with a CRI >= 0.9 underwent a major amputation before 12 months. Of all patients with a CRI only 15% underwent major amputation. The positive predictive value for major amputation before 12 months for patients with a CRI >= 0.9 was 100%. Conclusions A non-responsive sympathetic nervous system of the foot is a strong predictor of early major amputation (log rank p<0.001; HR 14.22; 95% CI 3.64 to 55.51).