News Release

Longer surgery duration associated with increased risk for blood clots

Peer-Reviewed Publication

JAMA Network

The longer surgery lasts the more prone patients appear to be to develop blood clots (venous thromboembolisms, VTE), according to a report published online by JAMA Surgery.

The association between longer surgical procedures and death, including VTE, is widely accepted but it has yet to be quantitatively addressed. More than 500,000 hospitalizations and 100,000 deaths are associated each year with VTEs. Examining the link between VTE and surgical time could allow for more informed medical and surgical decisions, according to the study background.

John Y.S. Kim, M.D., of the Northwestern University Feinberg School of Medicine, Chicago, and colleagues analyzed data from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) to look at the association between surgical duration and the incidence of VTE. The study included more than 1.4 million patients who had surgery under general anesthesia at 315 U.S. hospitals participating in the NSQIP from 2005 to 2011.

Study results found a total of 13,809 patients (0.96 percent) had a postoperative VTE; 10,198 patients (0.71 percent) experienced a deep vein thrombosis (DVT); and 4,772 patients (0.33 percent) developed a pulmonary embolism (PE). Compared with a surgical procedure of average duration, patients who underwent the longest procedures experience a 1.27-fold increase in the odds of developing a VTE. The shortest surgical procedures had lower odds. In three of the most common procedures (laparoscopic cholecystectomy (gall bladder removal), appendectomy and gastric bypass), surgical time was a risk factor for VTE.

"Given the observational design of our study, it is not possible to definitively conclude that the observed relationship between surgical duration and VTE incidence reflects a strict cause-and-effect relationship. ... This study provides quantitative validation of the widely held, but not previously substantiated, belief that longer operations are associated with a higher risk of VTE. These findings may improve VTE risk modeling, enhance existing prophylaxis guidelines and better inform surgical decision making," the authors conclude.


(JAMA Surgery. Published online December 3, 2014. doi:10.1001/jamasurg.2014.1841. Available pre-embargo to the media at

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Media Advisory: To contact author John Y.S. Kim, M.D., call Marla Paul at 312-503-8928 or email

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