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Perioperative red blood cell transfusions may increase VTE risk
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Perioperative red blood cell transfusions appeared associated with new or progressive venous thromboembolism in the postoperative setting, according to study results.
Researchers used the American College of Surgery National Surgical Quality Improvement Program database to analyze outcomes from 750,937 patients who underwent surgical procedures in 2014 at one of 525 teaching or nonteaching hospitals in North America.
Investigators calculated a postoperative VTE rate of 0.8%. This included 4,336 patients who developed deep vein thrombosis, 2,514 patients who developed pulmonary embolism, and 541 patients who developed both.
Perioperative red blood cell transfusion appeared associated with increased risk for VTE (adjusted OR = 2.1; 95% CI, 2-2.3), DVT (OR = 2.2; 95% CI, 2.1-2.4) and PE (OR = 1.9; 95% CI, 1.7-2.1).
The researchers also observed a dose-response effect. Compared with patients who underwent no red blood cell transfusions, the risk for VTE more than doubled among patients who underwent one transfusion, tripled for those who underwent two transfusions, and increased more than fourfold for those who underwent four transfusion events. The elevated VTE risk remained statistically significant across all surgical subspecialties.
HemOnc Today spoke with two of the researchers — Ruchika Goel, MD, MPH, assistant professor of pathology and laboratory medicine, assistant professor of pediatrics in the division of pediatric hematology/oncology, and assistant medical director of transfusion medicine and cellular therapy at NewYork-Presbyterian Hospital and Weill Cornell Medicine, and Aaron Tobian, MD, PhD, professor of pathology, medicine and epidemiology, director of the transfusion medicine division in the department of pathology at Johns Hopkins School of Medicine and Bloomberg School of Public Health — about the study, the implications of the results and what must be confirmed in subsequent research.
Question: How did this study come about?
Goel: An increasing number of clinical and basic science studies have suggested that red blood cells may have a role in the development of blood clots. Blood clots are a known surgical risk factor. Because patients can be in a state of immobilization after surgery, blood clots tend to form. They also can occur in the postoperative state once patients return home and are slowly regaining their activity levels. An increasing number of studies have suggested red blood cell transfusions, which commonly occur when patients have surgery, may have a role in the development of blood clots. This study aimed to see is there was any association between red blood cell transfusions given before, during and after surgery and development of any new clots within 30 days of a surgical procedure.
Q: How did you conduct the study?
Tobian: We analyzed prospectively collected registry data from the American College of Surgeons’ National Surgical Quality Improvement Program (ACS-NSQIP) database. NSQIP is a validated registry of 525 teaching and nonteaching hospitals in North America. The study included more than three-quarters of a million patients in the ACS-NSQIP registry who underwent a surgical procedure in 2014.
Q: What are some possible explanations for your results?
Goel: Increasing molecular and clinical evidence supports the role of red blood cells in normal clotting, as well as abnormal thrombus formation. There are multiple possible mechanistic pathways linking red blood cell transfusions to an increased risk for VTE. These mechanisms have been evaluated in various studies but none have been established. Largely, all proposed pathways suggest that transfused red blood cells modulate the inflammatory cascade. As inflammation and hypercoagulation are closely linked, red blood cell transfusion may further potentiate someone at risk of hypercoagulation or clot formation.
Q: How should this change protocols for blood transfusions ?
Tobian: This study demonstrates that there may be additional risks to blood transfusion that are not generally recognized in the community. Although additional research is needed to confirm these results, the findings from this study reinforce the importance of following rigorous perioperative patient blood management practices for blood transfusions and to limit blood transfusions to only when necessary. Transfusions should occur when necessary and be based off evidence-based medicine. All attempts should be made to correct preoperative anemia whenever possible using nontransfusion alternatives like iron and erythropoietin, with an eventual goal to avoiding transfusions before, during or after surgery.
Q: Could you also talk about managing VTE should it occur?
Goel: VTE — which includes DVT and PE — are serious, life-threatening conditions that require immediate medical attention. Early diagnosis and treatment are very important to prevent adverse outcomes. Treatment includes blood thinners or anticoagulant medications to keep the clots from continuing to form, and sometimes strong ‘clot busters’ or thrombolytic medications to actually break up a formed clot. Some of these are oral and some injectable medications. Sometimes, surgical interventions are needed to actually remove the large clots. More important than treatment, prevention is key. VTE is a major cause of illness and is responsible for an estimated 5% to 10% of all hospital deaths. About two-thirds of all in-hospital VTE events are preventable. Thus, we need to do adequate VTE prophylaxis and take every measure to reduce transfusions when possible.
Q: Do you have any final thoughts about how th ese results could or should change clinical practice ?
Tobian: We need to follow rigorous perioperative patient blood management practices. There is a need to correct preoperative anemia using nontransfusion alternatives whenever possible. During surgery, transfusion decisions needs to be based stringently, and transfusions should be used only when necessary. We also need to recognize that this is a retrospective cohort study. Additional research and prospective evaluation is needed to confirm these results. We are currently studying these relationships in children and neonates. – by Rob Volansky
Reference:
Goel R. JAMA Surg. 2018;doi:10.1001/jamasurg.2018.1565.
For more information:
Ruchika Goel, MD, MPH, can be reached at ruchikagoel1@gmail.com.
Aaron Tobian, MD, PhD, can be reached at atobian1@jhmi.edu.
Disclosures: Goel and Tobian report no relevant financial disclosures.