Best Practices for the Management of Thromboembolism - Episode 2

Risks and Risk Factors Associated with VTE

December 22, 2020

Experts in the management of VTE discuss the risks and risk factors for identifying VTE.

Charles Kurt Mahan, PharmD, RPh, PhC: Let’s shift into how you identify VTE [venous thromboembolism] risk and VTE risk factors for some of the more highly impactful venous thromboembolisms. The second part of that question is about how you would interweave what’s going on with the coronavirus pandemic, because it’s such a prothrombotic virus, and how you consider that as a risk factor if you do anything different with that virus.

Riley Bowers, PharmD, BCCP, BCPS: This backs me up in my lectures with my pharmacy students. The first step in identifying the VTE risk is understanding risk factors and how they tie back into Virchow’s triad in the path. In fact, if you go through most of the literature related to VTE risk factors, you’ll find that at least 80% of patients with VTE will have had at least 1 major risk factor, and that’s probably underestimating. Those are just the risk factors that we can find.

As far as the risk factors that we’re identifying, we probably don’t have time to go into every single one that has been shown to increase risk for VTE, but if you divide them into hereditary risks, antithrombin deficiencies, protein C and S deficiencies, and factor 5 Leiden mutations, then you have that set of risk factors. You have more patient characteristics and disease states that encompass the acquired risk factors. There are way too many of those to list, but 1 of the major ones is surgical patients. Patients who have undergone orthopedic general and cardiac surgeries are going to have a higher risk. Other risk factors include patients with active malignancy, patients who are pregnant, patients who may have a history of stroke or a previous VTE, especially previous VTE that puts them at extremely high risk. Patients with heart failure are also an often-forgotten risk factor. There are also patients who are older: older patients are in all our scoring tools. Patients who are obese, who are taking hormone replacement therapies, and who have reduced mobility at baseline are going to be at a very increased risk as well. As I said, this list is not all inclusive, but some of the risk factors I listed are definitely some of those that you’re going to see repeatedly on our risk-assessment models.

Paul Ament, PharmD: To echo what Riley has said, the estrogen use involved with some of the younger female patients and smoking are both risk factors. I will share this with you, though: A population that I don’t know that I’ve ever been involved with taking care of an acute blood clot is patients who are paralyzed, either quadriplegic or paraplegic paralysis. I’ve talked to other attendings about this, and you would think that, if anybody would be at tremendous risk, it would be patients who have paralysis. But I’ve honestly never been involved with an acute clot with that patient type.

Riley Bowers, PharmD, BCCP, BCPS: That’s a good point. I don’t think I have either, even though in 1 of our scoring systems, lower limb paralysis is a risk factor that contributes to the score.

To circle back to your question about COVID-19 [coronavirus disease 2019], Kurt. Is that considered a risk factor? At this point, we’re still learning a lot about COVID-19 and all its associated risks, but at this point I don’t think there’s any denying that COVID-19 is a definite risk factor for VTE.

Back in March, April, or going even into May, 1 of the common lab findings that we were seeing—and we’ve kept a pretty steady flow of patients with COVID-19 at our institution—were elevated D-dimers. That was a very common factor, especially in our patients with more acute illness, even those who were having to be admitted to the ICU [intensive care unit]. I know elevated D-dimers are nonspecific, but it has been associated with poor prognosis in our patients with COVID-19. There have been several case studies—probably more than I’ve read at this point—that have even shown development of PE [pulmonary embolism] in patients who had no other identifiable risk factors. They may score 1 or 2 on the Padua Prediction Score for risk of VTE and still develop PE before or within their hospitalization.

I’m not sure if we have enough literature to establish the exact risk, but you could be looking at 5%, 10%, or even a 15% chance of developing VTE in these severe patients, especially those who require intensive care.

Charles Kurt Mahan, PharmD, RPh, PhC: That’s a great point. Some of the data even suggest rates with pharmacologic prophylaxis onboard out of the Netherlands, and their rates were as high as 30% to 40% VTE even with appropriate prophylaxis. There are ongoing randomized controlled trials. I know Dr Alex Spyropoulos in New York is conducting a study looking at normal prophylaxis vs more aggressive treatment dose prophylaxis. I believe several other randomized controlled trials are ongoing.