Dr Mary-Margaret Brandt (Ann Arbor, MI): Using the National Trauma Data Bank to answer this ongoing question of where the disparities are in care, where they come from, and how we fix them is a really difficult problem. And I applaud you for this very complex and interesting effort.
Using the single diagnosis of lower extremity vascular injuries, I think, was an interesting tack, although I do have a few observations and some questions. Is your mechanism actually really a surrogate for socioeconomic status, penetrating? Injuries were much more common in the uninsured and also in people of color. Why did you pick 55 years of age as your age cutoff, if 65 is retired and over 40 is an old burn patient? Would you want to do quartiles or break that down a little more differently into different groups? And were there actually older, meaning octogenarians, who had blunt injuries? I think are first blush, lower extremity vascular injury seems very clean. But then when you get beyond---to blunt versus penetrating---we know blunt is fairly well scored with the injury severity score and penetrating is horribly done. And then you go from penetrating---is it a gunshot wound, is it a shotgun wound, is it a knife wound? That makes it even more difficult to tease out the variables. I think, again, mechanism may be a surrogate for socioeconomic status. It also may be a variable for the status of the population in which the patients actually live. And I look forward to further research. I think you did an excellent job.
Dr Marie Crandall (Chicago, IL): Thank you, Dr Brandt, for those comments and questions. Mechanism, I absolutely think, is both a surrogate for socioeconomic status and for race. There is a high degree of colinearity in both. For those of us who do trauma every day, we know that people of color and the uninsured are hugely disproportionately affected by the burden of penetrating trauma in the United States. Unfortunately, our best statistical methods to risk stratify are logistic regression, which I think is imperfect. And I think that this study has shown that it is imperfect to show that people are coming into this black box of what happens in the hospital. They are coming in from different places and with different injuries and potentially with different preexisting comorbidities from the social determinants of health that we think about from a population health perspective. So I think you are probably right in identifying the fact that these disparities still exist and that the mechanism is different based on socioeconomic strata and insurance, I think, is important. How to fix that and how to risk stratify that---especially with a trauma registry that is really incident- and not patient-based---is a challenge. The second question, “Why use 55 years of age as a cutoff?” It was because otherwise I would have had to really run 2 separate logistic regressions because the penetrating and blunt injured patients were so radically different and it lowered my degrees of freedom quite a bit. I still could have had significant P values, but it would not have been as valid a model. So, I chose over 55 years of age. And under 55 years of age is definitely the patient population grossly affected by trauma.
Then finally, lower extremity, vascular injury, heterogeneity---absolutely. That is an absolute challenge to this assessment.
Dr Nora Hansen (Chicago, IL): I had several questions. One of the observations you made was that the lack of insurance led to increased mortality. Do you think that now---with the health care reform andeveryone wanting to get insurance, or they want everyone to get insurance---will that change things? I suspect not. But if not, what factors would you need to modify to improve the mortality rates in this subset of patients? And then you comment in the paper that it is known that the ISS and other injury scores that are weighted toward a composite score really do not adequately reflect the severity of penetrating injury. What suggestions do you have to improve the methods of data collection and injury scoring? How would you implement them in your trauma center?
Dr Marie Crandall (Chicago, IL): The first question about health care reform is fascinating. So, of course, I cannot predict the future. I do not know the answer to that. And the disparities that exist before getting injured are really potentially causing huge effects on what happens after the patient is injured. But there are some maybe hopeful signs in the sense that in populations where health care provision has been relatively race and insurance neutral (ie, the VA population), and the military in particular, young military patients, those disparities are much less. And in fact, for young military recruits who have medical problems, their outcomes are equivalent irrespective of race. Of course, insurance is not an issue for either of those groups, but socioeconomic status may be. And those disparities are definitely lessened in a system where there is equal access and potentially reasonably equivalent service provision to all patients. How that will work out in practice for 300 million people, I cannot imagine. In terms of injury scoring, the only penetrating score that is used with any regularity--- and it is not included in the National Trauma Data Bank or the Illinois state trauma registry, with which I am familiar---is the Penetrating Abdominal Trauma Index, created by Moore et al. And that is actually very good, because obviously a nick on your liver that is not bleeding in hemodynamically is hugely different than a retrohepatic caval injury. And the ISS only has a difference of 1 to 6. But in terms of the effects on that, and whether or not you have associated colon and liver injuries and pancreatic injuries, is enormous for the trauma surgeon and for the patient. So, I think that turning attention to scores that we will be able to better quantify the effect of multiorgan system injury caused by penetrating trauma, I think, is very important.
Dr. Donald Reed, Jr (Fort Wayne, IN): I am just fascinated by the data mining of these huge databases. But on the slide that you alluded to, where you saw the difference in the insurance status and the result based on race and penetrating injuries, it seems to me, for those of us who do trauma on a daily basis, that one gunshot wound or penetrating trauma is not necessarily the same as the other. For instance, we get gunshot wounds all the time. If they are insured, it will often be a small caliber or self-inflicted wound. And we got a Gangland shooting 2 nights ago that had multiple gunshot wounds. So, I wonder if there is any way, you alluded to it a moment ago in your answer, to sort of tease that out. For those of us, like Maggie Brandt and I, who have done tours in the sandbox and seen soldiers with horrific injuries, ISS and trauma, the TS just does not seem to tease that stuff out. So, I am wondering if there is another way you can get at the heart of that data. In other words, you may have discovered something, but you have not really explained it. And see if you can work on that in the future.
Dr Marie Crandall (Chicago, IL): I find myself very frustrated with the data that we collect and then attempt to spit back out as answers. One of the ways that we determine the mechanism of injury for penetrating trauma is by E codes, the external cause disease. And let’s say a 965 would be gunshot wound. A 966, I think, is a stab wound. But each of those have subpoints and they are based on the ICD-9 coding. But if you look at gunshot wounds, the E coding has nothing that is a high-velocity weapon that is not a hunting rifle. So, our coders, who are urban---really, the workhorse of urban trauma in most places is the 9 millimeter. That is the majority of gunshot wounds, but higher velocity weapons with multiple gunshot wounds are very poorly coded at most institutions because of the limitations of E coding and ICD-9 coding. So, I think that that’s another challenge for the people who are moving forward with the trauma quality improvement project, like Shahid Shafi and people who are working on improving data collection and risk assessment, like Avery Nathans.
Dr Wendy Wahl (Ann Arbor, MI): If you look at truly isolated lower extremity trauma patients, so only an extremity vascular injury, and you will you see the same discrepancies with race as do you if you combine with other injuries? ISS is notoriously bad for head injury trauma, for chest and abdominal injuries, because you can have multiple organ injuries and get the same score. But you would expect the difference in your outcomes to be worse if you have an abdominal vascular injury with the lower extremity vascular injury than just the isolated lower extremity injury.
And you should be able to be tease that out because an ISS score of greater than 16 suggests probably that you have more than 1 organ injury. And certainly, if you go over 25, you definitely have more than 1 organ injury. And did you look at it by stratifying by those different ISS groups?
Dr Marie Crandall (Chicago, IL): That is an excellent point. We did not exclude patients who had more than 1 organ system injury. And the reason that we did that was because we wanted to have as large and inclusive of a data set as possible and make the real-world sort of trauma situation. But that does induce limitations, which is that the patient who is bluntly injured by being run over by a truck is somebody who is very different than who was running away from an assailant and was shot in the leg.
Dr Melina Kibbe (Chicago, IL): One of the things that comes to my mind when you present this data---and I think this is also an area that you are very interested in---is the time that it takes to get the patient from the field to the hospital. And that seems to me like one of the most logical areas that you are probably going tobe focusing on, because somebody who is in a worse socioeconomic area, is it just simply taking them longer to get to the hospital versus if they are in the Gold Coast in Chicago? And is that something you are going to be addressing? How do you address it? And then, once you figure out if that’s the problem, knowing you, you are going to fix that, or at least try?
Dr Marie Crandall (Chicago, IL): Dr Kibbe, that’s a really, really interesting and very huge topic. It has been the subject of many studies. So, we know that globally, rural patients who have similar injuries do worse than urban patients, because their time to presentation at a trauma center is longer. When those same studies have been attempted to be performed on urban trauma patients, there have been very mixed results. In fact, we have 2 papers that are currently under consideration for publication about this very topic. One looks at patients with penetrating thoracic injuries in an urban setting, and another looks at blunt abdominal trauma. And we looked at race- and insurance-based disparities and mortality for those patients. Another that is under submission right now looks at patients who have suffered gunshot wounds in an urban area and are looking at transport times in particular as well as geography. Not all systems are like ours. The city of Chicago has 7 level I trauma centers distributed around the city. But some of the greatest concentration areas of gunshot wounds are in the south side, where the nearest trauma center is nearly 5 miles away. So, there are higher transport times for those patients and patients in the south side. And what we have found---I am going to give preliminary results.
What we have found is if we excluded patients who had no vital signs on arrival, who never regained vital signs in the emergency department, if we excluded those patients, because there’s no question that if you live close to a trauma center, if you live across the street from a trauma center and you are shot and you are dead, you will get transported the half a block. But if you are 20 miles away, you will just be pronounced dead at the scene. So, we excluded those patients. For those patients, there is no question that the higher transport times increased mortality for penetrating trauma.
Dr Melina Kibbe (Chicago, IL): So, have you been able to relate the higher transport times to certain zip codes that are poorer socioeconomically?
Dr Marie Crandall (Chicago, IL): Yes. The trauma deserts are the exact urban deserts of grocery stores and libraries and educational obtainment.