Background: Vascular pathologies of the lower limb significantly contribute to the development of peripheral neuropathy, foot ulceration and amputation in people with diabetes. Establishing accurate vascular risk profiling in this population is challenging due to the nature of this multisystem disease process. This study evaluated the relationship between clinical vascular testing methods and history of foot complications (ulceration and amputation) and microvascular disease in community-based populations with diabetes.
Methods: Vascular measurements measured included the ankle-brachial index (ABI), toe-brachial index (TBI), continuous wave Doppler (CWD) and post occlusive reactive hyperemia (PORH) at the hallux (time to peak [TTP] and peak as a percentage of baseline [P%BL]). Diagnostic accuracy of measurements for peripheral arterial disease (PAD) was determined using colour Duplex ultrasound as the reference standard. Regression analysis was used to determine the ability of vascular measurements to independently predict the likelihood of a previous foot complication and history of microvascular disease.
Results: A total of 477 people with diabetes were recruited. The TBI had the highest sensitivity (84.4%, 95%CI 76.21 to 90.64) and CWD the highest specificity (93.33%, 95%CI 83.80 to 98.15) for PAD. A TBI of <0.60 was associated with an eight times greater likelihood of both a history of foot complications (OR=7.74, p=0.001) and of diagnosed microvascular disease (OR=8.4, p=0.01). Increased TTP was an independent predictor of history of foot complications (OR 1.014, p=0.04). The ABI and P%BL were only weakly correlated with history of foot complications and were not significant in the final regression models.
Conclusion: A low TBI is diagnostic for PAD and, is also predictive of a history of diabetes-related microvascular disease. Both a low TBI and a longer TTP are associated with increased likelihood of previous foot complications. Prospective research is required to determine the efficacy of these clinical tests for identifying “at risk” patients.