In the spring of 2012, as I was completing my endocrinology fellowship training at Johns Hopkins Hospital, I was approached by a vascular surgery colleague of mine, Dr. Christopher Abularrage, to discuss a possible collaboration. “We have to do something about the care of our patients with diabetic foot ulcers,” he began. “Too often, the amputations and foot ulcers I’m seeing in the hospital and in my clinic could have been prevented had these patients gotten the medical care they needed…How do you feel about starting a joint clinic at Hopkins with me, yourself, a podiatrist and wound care nurse all in one clinic space, so that patients can get truly multidisciplinary, coordinated care?”
“Yes,” I replied, “I’m all in!” Having seen the impact that diabetic foot ulcers and amputations have on the quality of life and long-term prognosis of my patients, I recognized the value a diabetes specialist to a diabetes foot and wound care team, many of whom had never received specialist care or who had financial or other limitations making it difficult for them to make multiple visits to different specialists.
In July 2012, the Johns Hopkins Multidisciplinary Diabetic Foot and Wound Service was formed. Patient demand was immediate. To meet patients’ needs, our team has grown steadily over the years and now includes an endocrinologist, diabetes nurse practitioner/educator, vascular surgeon, vascular surgical physician assistant, surgical podiatrist and wound care nurse, with other specialists from plastic surgery and infectious disease as needed. This work has been one of the most rewarding aspects of my career, as I see how important patient-centered and team-focused care is to ensure the best patient outcomes.
Diabetic foot ulcers are indeed one of the most devastating consequences of long-standing hyperglycemia, which leads to damage to the small nerve fibers in the feet and legs (neuropathy) and poor circulation (peripheral vascular disease [PVD]), which independently or together are the proximal causes of foot ulcers. Annual direct costs of health-care dollars in the U.S. spent on diabetic limb complications is estimated to exceed that of several leading cancers (breast, colon, lung, prostate).1 Hemoglobin A1c (A1C), a marker of average blood glucose control over the previous 90 days, is strongly correlated with risk of nerve damage and poor circulation. Importantly, maintaining an A1C level of less than 7% has been linked to improvements in nerve conduction velocity over time and lower risk of peripheral vascular and other cardiovascular outcomes.
After a few months seeing patients in our Diabetic Foot and Wound Clinic, my colleagues and I realized that we had an opportunity not only to work together to help our patients achieve improved wound healing and blood glucose control but also to learn from our patients to advance science. An observational cohort study in which our patients granted us permission to track their wounds and clinical course over time led to the discovery of patterns or predictors that are linked to the best outcomes. To date, we have followed 450 patients with approximately 1,000 wounds approaching seven years. These clinical data and course of our patients has generated important scientific insights, are summarized here.
Several established clinical factors can be used to predict wound healing for patients with diabetic foot ulcers. A recent classification system, the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI score), takes into account the size of the wound, the amount of ischemia (extent of vascular disease) and presence and extent of foot infection.2 This scoring system was created by an expert consensus group in 2014, around the time that our multidisciplinary foot and wound clinic was fully established. We had an opportunity to validate the significance of this score for the prognosis of our patients. We found that the WIfI scoring system (staged from 1 to 5, with 5 being worse prognosis) was highly predictive of wound healing but was not predictive of major amputation after one year.3,4 A strong correlation was found between the WIfI stage and total costs of care per wound episode. For example, a stage 1 wound costs on average $3,995 to treat, while a stage 4 wound costs a staggering $50,546.
One of the main missions of our outpatient diabetic foot and wound service has been to keep patients out of the hospital when possible. Repeated hospital admissions for patients with diabetic foot ulcers are common and associated with staggering costs.5 The overall costs of care for our patients who were readmitted were $79,315 versus $28,977 for those who were not readmitted. Of the overall $7.9 million spent on diabetic foot ulcers at our health system over a four-year period, $1.2 million (15%) were due to readmission costs.
Our cost-effective analyses highlight the importance of developing clinical care delivery models to divert the costs of care away from the inpatient setting to the outpatient setting when possible. Interestingly, our research found that costs of care were higher for more advanced stage wounds in the hospital, but the same was not true for the outpatient setting,6 suggesting that diverting care to the outpatient setting whenever possible may be a more cost-effective strategy. The ability for a health system to provide outpatient-based multispecialty care for patients with diabetic foot ulcers is no small feat; it requires geographically co-located and coordinated care by multiple specialists, which can be practically and logistically challenging. We feel that our multi-specialty approach achieves higher-quality care by improving communication between all team members, minimizing redundancy in care, decreasing overall patient visits and patient burden, and reducing overall costs due to more efficient and effective care.
Another finding of our research is that the WIfI score has proven to be a better predictor of wound healing than an alternative approach that examines areas of blood flow to the foot (called angiosomes) in the subset of our diabetic foot ulcer patients who have underlying PVD.7 Patients with PVD can often benefit from either endovascular or open surgical procedures to restore blood flow to the ischemic area. One approach, historically used by vascular surgeons is the “angiosome-targeted” approach, which aims to restore flow to the blood vessels supplying the area where the wound is located. Evidence is mixed about the effectiveness of using this approach alone to predict wound healing and major amputations. Our finding that the WIfI score is a better predictor of wound healing than the direct angiosome perfusion approach suggests that wound severity should be taken into account as much as vascular flow when predicting a patient’s clinical course.7
As a diabetes specialist, I focus largely on my patients’ blood glucose control. While there is strong evidence to support the role of blood glucose control to prevent nerve damage, PVD and ulcers from occurring, there is less known about the role that blood glucose control can play in patients once they have actually developed a diabetic foot ulcer. A strength of our observational study is collection of A1C over time in our patients, allowing us to look prospectively at the relationship between blood glucose control and wound healing or amputations. Our findings were surprising. In patients with baseline A1C levels less than 7.5% (acceptable control), we found that those patients whose A1C levels decreased the most had slower wound healing than those whose A1C levels either remained the same or increased.8 This finding was somewhat counterintuitive, given the relationship between higher A1C levels and the risk factors for foot ulcers (neuropathy and PVD). In patients whose A1C levels were 7.5% or higher (less than optimal control), however, we did not see any relationship between A1C lowering over time and wound healing. One explanation for this may be that the “damage is already done” in these patients and that further declines in blood glucose will have minimal impact on wound healing. Even without substantial benefit related directly to their wound, we strive to attain A1C targets in our patients with diabetic foot ulcers because of the potential impact for damage to other organs (eyes, kidneys, etc.).
A challenge with my patients relates to increasing costs of diabetes medications. Many of our patients struggle financially with the skyrocketing costs of insulin and other diabetes medications. To combat this serious problem, the American Diabetes Association is actively lobbying to get drug companies to reduce the costs of insulin.9 With my patients, I’ve observed how challenging it is to manage this chronic disease even without having to worry about being able to afford their medications. Along these lines, our team was interested in exploring the role that socioeconomic status plays on wound outcomes in our patient cohort. We obtained the area deprivation index for each of our patients. This is a geographic-based measure of socioeconomic deprivation at the neighborhood level, which takes into account education levels, employment rates, median family income, single-parent households and several other factors. Interestingly, in our patient cohort, we found that wound healing was largely unrelated to neighborhood socioeconomic disadvantage.10 These findings were encouraging, as they seemed to suggest that our unique clinical model could overcome any negative effects in wound outcomes that patients might experience as a result of their socioeconomic status.
Diabetic foot ulcers remain a significant problem to be addressed by the medical and scientific community. Clearly, the most effective strategies will target early blood glucose control and prevention. However, for those patients who do go on to develop the complications that lead to a diabetic foot ulcer, our clinical experience and research findings — together with experiences from other institutions11 — suggest that the ideal scenario is in the hands of a multidisciplinary team.
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