A newly developed model may help predict the risk of major limb events in people with diabetes, even among people without a history of peripheral arterial disease (PAD), according to an article published in the journal Diabetic Medicine.
It’s well known that people with diabetes — both type 1 and type 2 — are at higher risk for major problems affecting a limb, usually the foot or leg. These problems may include an ulcer (open sore) that is resistant to healing, which can lead to an infection and, in serious cases, amputation. Major limb events are more common in people with PAD, in which blood flow in the limbs is restricted by fatty deposits in the arteries known as plaque. But PAD doesn’t always lead to noticeable symptoms and may go undiagnosed, which means that a higher risk for limb problems may go unnoticed in many people with diabetes.
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For the analysis that led to the newly developed model, researchers used data from a study called EXSCEL (Exenatide Study of Cardiovascular Event Lowering), looking at factors that affected whether participants developed major limb events like gangrene, revascularization surgery, and amputation. Out of 14,752 participants with type 2 diabetes, 3.6% experienced major limb events during the study period. As noted in a Healio article on the study, these 736 events (seen in 523 participants) included 247 amputations, 166 episodes of gangrene, and 323 revascularization surgeries.
Factors that made major limb events more likely included peripheral arterial disease (4.83 times the risk of a major limb event), a prior foot ulcer (2.16 times the risk), a prior amputation (2.00 times the risk), current smoking (2.00 times the risk), insulin use (1.86 times the risk), coronary artery disease (1.67 times the risk), and being a male (1.64 times the risk). Other factors found to increase the risk for major limb events included cerebrovascular disease (blood vessel disorders affecting the brain), neuropathy, former smoking, older age, and a higher A1C level (a measure of long-term blood glucose control).
Model creates risk score for major limb event
The researchers used these factors and others to create a risk score, in which people receive a score ranging from 6 to 96 points to indicate their risk for a major limb event. This model was found to have what’s known in statistics as a C-statistic of 0.822, meaning that a person who ends up having a major limb event would have a higher risk score than someone who doesn’t have a major limb event 82.2% of the time. A score of 40 or below indicated a risk of 0.8% or lower that a person would experience a major limb event within three years. A score of 65 to 69 indicated an 11.8% risk for a major limb event, and a score of 85 to 89 indicated a 64.5% risk.
The researchers concluded that they had developed a risk score with “good performance” that could help identify people who require more care and follow-up to help prevent and identify major limb problems — especially those without a documented history of peripheral arterial disease. “Although the majority of major adverse limb events happened among participants with peripheral artery disease, a significant minority occurred among participants with no documented history of peripheral artery disease,” they wrote. “Individuals at high risk of major adverse limb events without a documented diagnosis of peripheral artery disease could be usefully identified by a risk score as they may require additional evaluation to rule out asymptomatic peripheral artery disease.”
Want to learn more about PAD? Read “Diabetic Leg Pain and Peripheral Arterial Disease.”
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