Diabetic foot: introduction

Scope and trends

As of 2017, nearly 25 million people, or 9.7% of the population, were diagnosed with diabetes in the United States. In 2020, this number was reported to have increased to over 34 million people, or 10% of the population. It is estimated that 15%–25% of diabetic patients suffer from a diabetic foot ulcer DFU in their lifetime. Approximately half of these patients will experience infectious complications warranting hospitalization. Based on these statistics, 5.1–8.5 million patients in the United States suffer from a DFU on an annual basis. By 2050, the number of people in the United States with diabetes is expected to exceed 48.3 million, which will consequentially increase the DFU burden.

Infected DFUs carry significant risk for adverse outcomes compared to DFUs that are not infected. For example, for patients with infected DFUs, the risk of hospitalization is 55.7 times greater and the risk of amputation is 154 times greater relative to patients with non-infected DFUs. Unfortunately, some research suggests that the rate of complications secondary to DFUs is increasing. Analysis of emergency department discharge data from the Agency for Healthcare Research and Quality (AHRQ) demonstrated that 8.7% of the 54 million cases presenting to emergency departments between 2006 and 2010 were associated with a diagnosis of diabetes. Of these cases, 81.2% required subsequent inpatient admission for management. Compared to the decade prior, the incidence of diabetic emergency department cases dramatically increased. Between 1997 and 2007, only 20.2 million, or 1.7%, of emergency department cases involved diabetes.

While some studies suggest that rates of diabetes-related complications are decreasing, these trends are likely indicative of an increasing disease burden rather than a true decrease in complications. For example, data collected between 1990 and 2010 demonstrate declining rates of diabetes-related complications such as lower extremity amputation, end-stage renal disease, myocardial infection, stroke, and death. However, the same period also witnessed a two- and threefold increase in the incidence and prevalence of diabetes, respectively. Similarly, annual rates of lower extremity amputations in diabetics also decreased between 1990 and 2010, by 50%. Yet, the same period also witnessed an absolute increase of more than 20,000 diabetic amputations per year. Data from the National Inpatient Sample (NIS) demonstrated that this decline in amputation rates, likely masked by the increasing prevalence in diabetes, reversed course between 2009 and 2015, increasing by 50% to 4.6 per 1000 adults. Increased rates were witnessed in both minor and major amputations, with minor amputations undergoing a more dramatic increase. As the incidence of diabetes increases, an increased prevalence of complications will follow. In 2006, 1.6 million people underwent amputation in the United States; in 2050, this number is expected to climb to 3.6 million.

Mortality

Once a DFU develops, patients are subject to significantly increased mortality rates. Patients with DFUs have a risk of death that is 2.5 times higher compared to diabetics without DFUs. One-year mortality rates for DFU patients is estimated to be 5%. If the DFU becomes infected, this rate increases to 12.5%–25%. The mortality rate dramatically increases even further at five years, increasing to an estimated 39%–68%, a rate comparable to several types of cancer, such as breast and Hodgkin lymphoma, and congestive heart failure. Furthermore, DFU patients typically present with metabolic syndrome, the constellation of insulin resistance, central obesity, dyslipidemia, and hypertension, placing them at increased risk of cardiovascular events. Even with aggressive management, many DFUs will require amputation, often within just four years of diagnosis. The risk of amputation in diabetics is 30–40 times higher than non-diabetics. Following amputation, mortality is estimated at over 33%, 53%, 64%, and 80% at 1, 3, 5, and 10 years, respectively.

Costs

Conservative estimates reveal that annual Medicare spending on wounds exceeds $28 billion and that management of DFUs accounts for over 20% of this spending. The total direct healthcare cost of diabetic care in the United States in 2012 was estimated to be $176 billion; one-third of these costs were attributable to the management of DFUs. In 2017, direct health expenditure costs for diabetes increased to $237 billion. Adjusted cost of inpatient care for a DFU is estimated to be $8465 per admission and major amputation of a limb with a DFU increases this cost to $18,877.