MedicalResearch.com Interview with:
R. Grant Steen, PhD
Durham, North Carolina
MedicalResearch.com: What is the background for this study? What are the main findings?
: When we started this research, it was really only guesswork as to how big a problem fracture nonunion really is. What we've done is to work with an enormous database of patient health claims, with two goals.
First, we wanted to characterize how common fracture nonunion is among patients across a wide age range.
Second, we wanted to identify risk factors that make a patient more likely to have problems healing.
We've now succeeded in both aims. We know that roughly 5% of fracture patients will go to nonunion, and we know a whole host of risk factors that predispose them to do so.
Most of the risk factors that we've identified—with a few exceptions—would not be a surprise to physicians who treat fracture patients. However, what we've done is to put all of these risk factors in a broader context, so that we know which risk factors are most important and which are less so.
For example, it has been known for a long time that smoking is a risk factor for nonunion. What we've shown is that, in the scheme of things, it's not all that important. Let me be more precise here, because this is an important point. If all you know about a patient is that they smoke, we've shown that smoking is associated with a 62% increase in risk of nonunion. That's a lot. But, as you learn more about that patient and can factor that new knowledge into a risk prediction, it turns out that smoking, all by itself, increases the risk of nonunion by only about 20%. However, smoking is a surrogate marker for a range of other risk factors that also increase risk, including male gender, cardiovascular disease, obesity, vitamin D deficiency, alcoholism, and so on. Once you factor these separate risk factors into your new nonunion prediction, you have a much more nuanced—and probably much more accurate—prediction of nonunion risk.