Risk for Clot Increases After Surgery With Transfusion

Veronica Hackethal, MD

June 13, 2018

Receiving a red blood cell (RBC) transfusion around the time of surgery may double the odds of developing venous thromboembolism (VTE), or blood clots, up to 30 days after surgery, according to a study published online today in JAMA Surgery.

The study is one of the first to focus on the potential link between perioperative RBC transfusion and VTE in general surgery and various surgical subspecialties, note Ruchika Goel, MD, MPH, from New York Presbyterian Hospital, Weill Cornell Medicine, New York City, and colleagues. 

"These findings should reinforce the importance of rigorous perioperative patient blood management practices," they write.

Hospital-associated blood clots account for 5% to 10% of all hospital deaths. With proactive management, research suggests that up to 70% of them may be preventable.

Various factors may increase the risk for VTE, including surgery, general anesthesia, and/or an RBC transfusion around the time of surgery.

In particular, research suggests that RBCs may have inflammation-promoting properties that may lead to clots. During storage, they may also acquire lesions that promote blood clots. Animal and clinical studies have also pointed to a role for RBC transfusions in the development of blood clots. 

To further evaluate the issue, researchers used prospectively collected data from the American College of Surgery National Surgical Quality Improvement Program (ACS-NSQIP) database. The registry includes information on adults who undergo surgery (with the exclusion of trauma or organ transplants) at 525 hospitals in North America.

Of 750,937 individuals who underwent surgery in 2014, 6.3% (n = 47,410) received at least one perioperative RBC transfusion and 0.8% (n = 6309) experienced a postoperative VTE, including 0.6% (n = 4336) with deep venous thromboembolism (DVT), 0.3% (n = 2514) with pulmonary embolism (PE), and 0.1% (n = 541) with both DVT and PE.

After adjustment for 11 risk factors previously associated with VTE, perioperative RBC transfusion was linked to approximately twofold greater odds of VTE (adjusted odds ratio [aOR], 2.1; 95% confidence interval [CI], 2.0 - 2.3), DVT (aOR, 2.2; 95% CI, 2.1 - 2.4), or PE (aOR, 1.9; 95% CI, 1.7 - 2.1).

Results also showed a significant dose-response effect for perioperative RBC transfusion and VTE. Compared to no RBC transfusion, odds of VTE doubled for a single RBC transfusion (aOR, 2.1; 95% CI, 2.0 - 2.3), tripled for two RBC transfusions  (aOR, 3.1; 95% CI, 1.7 - 5.7), and increased by 4.5 times for more than three RBC transfusions (aOR, 4.5; 95% CI, 1.0 - 19.4; P < .001 for trend).

Further analyses showed similar results across six surgical subspecialties and after adjustment for potential baseline differences in participants.

The authors note several study limitations. The study could not differentiate between chronic and new VTE, or distinguish between cell-saver and stored RBCs, which could have affected results. Also, the study could not account for concurrent medications, family history of VTE, or underlying diseases that promote blood clots.

"These results need prospective validation in cohort studies and randomized clinical trials; if proven, they underscore the continued need for more stringent and optimal perioperative blood management practices in addition to rigorous VTE prophylaxis in patients undergoing surgery," Goel and colleagues conclude.

The study was supported in part by the National Institutes of Health and Weill Cornell Medical College. The authors have disclosed no relevant financial relationships.

JAMA Surg. Published online June 13, 2018. Full text

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