Predicting which patients will develop chronic critical leg ischemia.

Although numerically far less than claudicants, patients with critical leg ischemia (CLI) demand a disproportionately large commitment both in medical effort and economically and represent the major workload for vascular surgical units. The incidence and prevalence of CLI is approximately 500 to 1,000/million/year. The risk factors for the development of CLI are largely the same as those for the progression of local disease in IC, the most important, apart from age, being smoking and diabetes. Major amputation is more common amongst claudicants who are heavy smokers and who continue to smoke, and although stopping smoking slows down the vascular changes and reduces the likelihood of symptomatic progression, it does not reduce the risk of major amputation over the following 2 to 3 years. Diabetic PAOD patients are about 10 times more likely to come to amputation than nondiabetic PAOD patients, and the prevalence of gangrene is 20 to 30 times higher in individuals with diabetes and PAOD compared with nondiabetics with PAOD. There is some evidence that most of these effects of risk factors are additive.