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Board Review Diabetic Foot

Identifying the Foot at Risk

Lawrence Lavery, DPM, MPH

Lawrence Lavery, DPM, MPH gives an in-depth look at diabetic foot ulcerations and who is at greatest risk. Dr Lavery reviews both local and global risk factors for developing a diabetic foot ulcer and discusses the survival rates after amputations. He also demonstrates how proper preventative care and identifying these risk factors can potentially save your patient's lives.

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Goals and Objectives
  1. Identify which of your patients are at risk for developing risk factors
  2. Identify which conditions put patient at greatest risk for developing a foot ulcer including local and global risk factors
  3. Discuss the diabetic foot classification and how it can be used to predict the development of foot ulcerations
  4. Describe the standard of care for diabetic foot ulcer prevention and discuss how enrolling a patient in such a treatment plan can improve their outcomes
  • Accreditation and Designation of Credits
  • CPME (Credits: 0.5)

    PRESENT eLearning Systems, LLC is approved by the Council on Podiatric Medical Education as a provider of continuing education in podiatric medicine.

    PRESENT eLearning Systems, LLC has approved this activity for a maximum of 0.5 continuing education contact hours.

    Release Date: 03/16/2018 Expiration Date: 12/31/2018

  • Author
  • Lawrence Lavery, DPM, MPH

    Professor and Director of Clinical Research
    Department of Plastic Surgery
    University of Texas
    Southwestern Medical Center - Dallas, TX

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  • It is the policy of PRESENT e-Learning Systems and it's accreditors to insure balance, independence, objectivity and scientific rigor in all its individually sponsored or jointly sponsored educational programs. All faculty participating in any PRESENT e-Learning Systems sponsored programs are expected to disclose to the program audience any real or apparent conflict(s) of interest that may have a direct bearing on the subject matter of the continuing education program. This pertains to relationships with pharmaceutical companies, biomedical device manufacturers, or other corporations whose products or services are related to the subject matter of the presentation topic. The intent of this policy is not to prevent a speaker with a potential conflict of interest from making a presentation. It is merely intended that any potential conflict should be identified openly so that the listeners may form their own judgments about the presentation with the full disclosure of the facts.

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    Lawrence Lavery has nothing to disclose.

  • Lecture Transcript
  • Bob: Our next speaker again is no introduction, this is his third and final talk for us at least I believe it is. And Larry’s done some good work on identifying patient risk. So I’ve asked him to talk a little bit on the prevention in terms of being proactive in identifying your patients who are at risk for ulcerations. Because that I think is the first step in prevention, so let’s welcome Larry Lavery back to the podium.

    Dr. Larry Lavery: Thanks, Bob. So this is an area that I’ve been particularly interested in. In 1998, I left the University of Texas Health Science Center in San Antonio to be the medical director of a Diabetes Managerial Program because it can allow me to take the stuff I had done in research and apply it. And so I’m going to show you our kind of lessons learned from a disease management model. So when I think of risk there’s a couple of ways to look at it. There’s kind of 3,000 foot view where you look at kind of populations and who’s at risk. I don’t know if that’s necessarily helpful for us but it could be. You can look at risk factors, specific risk factors. We’ll talk just a little bit about those and then you can look at risk classification systems. And I think never one is interested in algorithms and how I put people on more boxes. I actually think this – if you’re the CFO, I think you love this because this will tell you where you’re spending your money and who those people are. And the people you’re spending your money on the most are actually relatively easy to get your arms around. So this is tantalus trying to reach for the fruit that you never gets. It’s probably not unlike what we do. So this was sent to us when I was at Scott and White by the ID guys. They sent to every member of the physician group. One other things are not going – you don’t see very often in the literature is what we do that puts patient at risk. So there was – I forget who commissioned the study or who report the study. But in chronic disease in United States about 60% of patients get recommended care, 20% get care that’s contraindicated. It’s probably much worst in the diabetic foot because it’s just not looked at by most patients. So I mean there are high risk physicians and hopefully we’re here to reduce our risk. So one of the ways to look at this is – look at race and ethnicity. So if you look – this is a study that was done in South Texas where we looked at amputation instance and we had pretty good county prevalence rates of diabetes from San Antonio Heart Study which used a very similar catchment area. So we looked from San Antonio to Corpus Christi, San Antonio to Toledo and everything in the Rio Grande Valley. So we went to about 25 hospitals abstracted their amputation records and looked at this by race and ethnicity. So in South Texas, non-Hispanic whites, the instance of amputation was about 60 per 10,000. It was a 150% higher in Mexican-Americans and about 200% higher in African-Americans. Now, South Texas does have a large African-American population, but this looks like it holds true in other populations. If you looked at gender, it’s bad to be a man. I mean man have twice the instance of amputation as woman in every race group. And so one of the things that are basic science research group is looking at now is sexual dimorphism in lower extremity wounds and amputations. It’s not just that we are non-compliant butt heads. I mean there’s more to it. That’s probably a big chunk of it but I think everyone passes it this off as – it’s what we do. But it’s probably also just how we’re made. So race is a big difference. Gender is a big difference in amputation outcomes. I think the other population is easy to get your arms around to see how bad the risk is is the dialysis patient population. So in that study, we looked at a 1,043 amputations and so because there wasn’t HIPAA at the time and we are able to get patient’s name, their home address, their social security number, all kinds of stuff that an IRB would not allow you to collect. So I asked our IRB, I thought they wouldn’t let me use this data. And they said, “Well, you got it under the IRB 15 years ago, you can use the data.” So we went to the online mortality database.

    [05:03]

    It’s free and looked up mortality of these thousand amputees. So we’re basically looked at people that were being dialyzed only 128 of them, people that who their EGFR was between 15 and 60 and people whose EGFR was greater than 60, so no CKD. So if you looked at the amputation level based on their kidney status about 30% of the dialysis patients had foot amputations, 54% that had no renal disease, 40% the people had some level on CKD. And this is probably just a marker for their vascular disease but when the abstract medical records in hospital no one does a good job of measuring that in any way that you can operationalize. So if you looked at proximal amputations, 71%, 62%, 43% all strongly related to their renal status. And survival is as has been reported in other studies but this is probably the biggest that reports survival based on amputation level, the people that have proximal amputations die pretty [Indiscernible] [06:17] fast. If you look at death by renal status, it also is pretty dramatic. So first year mortality, if you have an amputation and you are on dialysis, it’s 49%. If you go to the other end of the spectrum with no chronic kidney disease only 14%. As a matter of fact, the five year survival is better than the one year survival in patients that have no kidney disease. If you look at – so this is 10-year survival data, this is about a [STIPA] [06:49] curve as you’re going to get for mortality. Much deeper than most malignancies, so a very early separation in survival and people would have that required dialysis, the people that have an abnormal EGFR and people have abnormal kidney functions based on EGFR. From 30,000 feet, if you were looking for a population to provide prevention this would be it. So this is a study that we did in collaboration when I was at Scott and White which is a large, multi-specialty physician group about 800 physicians, 32 clinics and five counties in the middle of nowhere in Texas. And then collaboration with Andrew Bones [phonetic] group which they have a huge dialysis center in Manchester. So we look at pre-dialysis patients and dialysis patients to see really what the difference is in people that have dialysis and CKD. They’re worst and everything. They have more sensory neuropathy about a two-fold increase risk of having sensory neuropathy, 2.4 increase risk for peripheral vascular disease and we do a horrible job of measuring this and operationalizing this. This is all based on arterial doctors which I think in this patient population aren’t very helpful. So this was based on an ABI that was less than 0.9. About a two-fold increase risk of having a foot ulcer and 2.6 increase risk of having a history of previous amputation. Five-fold increase risk of having a current ulceration at this cross sectional study at one visit in the dialysis center or one visit in the outpatient center. These are the highest risk group. Everything about them looks bad. But maybe it’s us as well, so only 44% of the dialysis patients routinely attend podiatry clinic. Only 61% see an endocrinologist for their care. Their care falls to their nephrologist. Only 60 or we do a bad job for everyone getting protective shoe insoles, 16% of dialysis patients, 8% in pre-dialysis patients get therapeutic shoe insoles. I can tell you at Scott and White, we have three pedorthist, the hallway over from where the podiatry clinic is. It’s covered by healthcare. I thought when we were going to look at these numbers would blow these numbers off the page and it would be not representative of what happens in your life. It’s horrible. This is like the mainstay of prevention and we’re not doing a very good job. So maybe it’s us, maybe we’re just this guy that isn’t washing his hands. Let me go back. Okay. So let me see if I have the right thing. Go the wrong way. Let’s skip the bunch of this evidently. Okay. So another way to look at this is to look at established risk factors.

    [10:01]

    And so I think you can look at kind of global risk factors, systemic disease and you can look at local risk factors. See what’s going on in their lower extremity. Like I said before the amputations, male gender is a risk factor in studies as high as almost six-fold increase risk of having a foot ulcer amputation for men. Older patients, patients with longer duration of diabetes, people with poor glucose control and diabetes-related comorbidities. All that makes sense. This isn’t really going to help necessarily focus on who you need to identify except these maybe coded better if you look at claim’s data to get your people. So this is more of the 30,000 foot view. If you look at local risk factors, what’s happening in the foot? The strongest risk factor people who got a previous – if you had an ulcer and amputation, you had as high as a 40-fold increase risk of having another of that usually within the next year. Sensory neuropathy is seven to 30 fold increase risk, people with peripheral vascular disease, two to three fold risk. And I really think this is because we still need better tools to operationalize this. We still don’t know what’s going on in the foot. And then there are biomechanic abnormalities, limited joint mobility, structural deformities, abnormal foot pressures of about two to five-fold increase risk. Again, it’s hard to kind of put structural deformity in some kind of order of severity that people can agree on. I think this is probably a stronger risk factor but we just don’t do a good job of measuring it and categorizing it. So one of the things I think we always fall back on is foot pressures. We know that foot pressures are related to ulceration, people have high foot pressures take longer to heal. Ulcerations are usually at the site of their highest pressure on their foot. If you look at time to healing related to foot ulcers, men take longer than women. People with poor glucose control takes longer, people of high foot pressures take longer and people with longer wounds. All the things that some other risk factors kind of help us understand. So is there a safe area? What’s bad and what’s good? The data isn’t really good. By itself, pressure isn’t a great tool to evaluate risk. So this is from that cohort of 60 in 666 people in a Diabetes Managerial Program that we evaluated that got education, they had open access for shoes insoles. And this is just as slice that are people that have neuropathy. So vibration perception threshold greater than 25, abnormal [Indiscernible] [12:43] and we look at the people in the next two years that didn’t develop a foot ulcer and people that did develop a foot ulcer. So got this beautiful bimodal distribution but there is a huge proportion of these folks that have low pressures and a reasonable chunk of these folks that have high pressures and don’t ulcerate. If you just looked at neuropathy and vascular disease. If you look at this with the receiver operating curve either this one or this one, both from different studies, it’s about as good as flipping a coin. It’s not going to really help you identify who’s at risk looking at foot pressures even in people with neuropathy. So I think one of the conventions that we think are true is that people that have diabetic foot ulcers have high pressures and have really high activity levels. They walk all over the place and we tell them that they shouldn’t walk. They’re really active patients. We tell them they shouldn’t walk and they still walk. Less weight bearing would be better. But if you look at the data and there’s probably three or four pretty nice studies now that you have this nice little activity monitors. If you look at controls without diabetes, they take about 10,000 steps a day. Type II Diabetics with no neuropathy 6,600 steps a day, diabetics with neuropathy 4,500 steps a day and people that have neuropathy and ulcers 1,400 steps a day. So the couple people I’ve looked at again these controls, people with neuropathy and ulcer group, this is a collaboration with Mike Millers group at Wash U that showed the people of foot ulcers had 50% less cumulative stress. They look at pressure, the pressure time in enrolled, the number of steps and came up with the stress measurement. Dave Armstrong came up with almost the same conclusion that people – the small number of folks that ulcer had 42% fewer steps during the course of the day on average than the 92 patients that didn’t develop ulceration. So maybe it’s not activity. It’s not what when we think activity is.

    [15:00]

    It’s probably a combination of these things that we still have this assessment of stress is not a good indeed of measurement or a tool for us to measure this. We still can operationalize this well. We still can operationalize vascular disease as well. So it’s probably a more complicated and more difficult to measure than we can get our arms around it. Probably a convenient way to look at this is to look at risk classifications. This is really kind of a rip off of the Carville in sensitive foot risk classification except in that model they didn’t really have vascular disease. So this was just kind of put here by convention. So group zero, people have no neuropathy or vascular disease or ulcer and amputation history. Group one, are people that just have neuropathy. Group two, are people have no neuropathy and foot deformity and you can operationalize that in a variety of ways or vascular disease. And most people that have neuropathy have peripheral vascular disease as well or people that have a history of ulcer amputation Charcot or bypass. So if you look at this, so we reported this Jennifer Mayfield, a few years earlier reported almost identical numbers. If you go down this list there is an increased risk as you go through each risk category of having an ulceration. 3-6-fold risk of people that have or previous ulcer event or amputation. So this is some work by Andrew Peters who was a fellow at UT in San Antonio and I was an ID guy in the Netherlands. Looked at a 30-month followup of 213 patients, 5% had no risk factors and or 5% of people have no risk factors ulcerated, 14% of the people that had no neuropathy ulcerated. 13% of people with neuropathy and deformity or a vascular disease, 2% had amputations and 64% of people that have previous events ulcerated, 26% had another amputation. So that classification seem like it works. And if you look at the data, it’s really pretty flat in these two groups and there’s this huge jump at the end. So we took data from this disease management group and looked at 1,666 patients, the first group that we screened and we followed them for about 28 months. So at screening about 59% feet group zero, 6% feet group one, about 20$ had neuropathy and deformity or peripheral vascular disease, about 13% had vascular disease defined by ABI less than 0.8 and 16% had a history of previous pathology. So we pulled this out and looked at people with ulcer history, amputation history, people had just had peripheral vascular disease regardless of their neuropathy status. And now we left these two groups alone. We looked at ulcers, amputations, hospitalizations, infections, recurrent ulcers and we divided this up a bunch of different layers. So if you look at these first groups, no neuropathy or vascular disease as we define it. People had no neuropathy or neuropathy and deformity. There’s no a big difference in these two groups. There is actually a significant difference between the no disease in these two factors but it doesn’t seem like it’s startling. Few amputations, few hospitalizations, these folks don’t cost you money if you’re the CFO. The next big group are people have peripheral vascular disease, 14% of them have ulcers every year. 4% having amputation and 16% are hospitalized. I really think this difference is because in San Antonio we had a really great vascular surgery group. And we kind of switch practice from people having an emergent bypasses to failing conservative care having angiogram and being bypassed. I think that’s what explains this difference. But the biggest risk group are people who never have previous ulcer amputation even with education, pedorthic care kind of structured podiatry care that’s open access. A third of these people ulcerated every year. There’s a big jump then and the people that have amputation events and people that are hospitalized, half of the people with the previous amputation are hospitalized. Now the numbers get kind of low even from this 1,600 patient group. If this was a larger N these numbers may change. So if you look at this data, if you’re the CFO, this is kind of classic 2080 phenomenon. 20% of your patient population, people of peripheral vascular disease, ulcers and amputation history account for 70% of your ulcers and 90% of your hospital day. So if you want to save your hospital money, you can find these people. You can find the ulcer and amputations through people from claims data. The problem with the vascular group is you have to lay your hands on those people and test them.

    [20:02]

    So these are little bit harder to identify but you can identify your highest risk, your most costly patient from claims data. So if you look – I guess I didn’t have – maybe there’s this fatalistic approach to diabetic foot care or it’s a great opportunity to go and kind of change this scenario into where we can reduce the risk of disease by 50%. And keep people and their quality of life high until they die. So I think the lower extremity model there are key factors for prevention. You have to pick the right target, you have to spend your money wisely. You have to have the right intervention which I still don’t think we understand extremely well. But the standard of care is education which our patients don’t get. Shoe insoles which our patients don’t get. Appropriate referral which our patients probably don’t get and multi-specialty care which it’s rare that our patients get. So accountable care organizations I think are going to make us do this. They’re going to make us collaborate so we can get paid. With that my red light is on and thank you.