Longer the Surgery, Higher the Likelihood for Venous Thromboembolism Development

Increasing surgical duration was associated with an increase in venous thromboembolism (VTE) for patients undergoing surgery, according to findings published in JAMA Surgery.

Researchers from Northwestern University Feinberg School of Medicine retrospectively examined the data from nearly 1.5 million surgical patients under general anesthesia across 315 US hospitals between 2005 and 2011 in order to examine the link between surgical duration and incidence of VTE. The rates of deep vein thrombosis (DVT), pulmonary embolism (PE), and VTE were measured within 30 days of the initial operation.

DVT was defined as any new clot or thrombus anywhere in the venous system and confirmed via duplex ultrasonography, venogram, or computed tomography. The researchers defined PE as diagnosed via computed tomography (spiral or angiogram), pulmonary arteriogram, or high probability ventilation perfusion scan.

There were a total of 13,809 (0.96 percent) patients who experienced post operative VTE. Additionally, 10,198 patients (0.71%) who experienced a DVT, and 4,772 patients (0.33%) developed a PE.

There were just over a thousand patients (1,161 patients or 0.08%) who had a DVT and PE. The researchers found that each of these events consistently increased as the duration of the surgical procedure increased. The authors believe their study can assist surgical planning and management.

“Such risk stratification could help target chemoprophylaxis strategies for perioperative care physicians, surgeons, and anesthesiologists and better inform patients and clinicians of the potential hazards associated with prolonged surgery,” the authors wrote.

When compared to patients undergoing surgical procedures of what the researchers termed “average duration” — surgeries in the third quintile – patients who experienced the longest procedures saw a 1.27 fold increase in the odds of developing a VTE. Contrastingly, the patients who underwent the shortest procedures experienced an odds ratio of 0.86 for developing VTE.

“Clinically, this relationship between operative time and the incidence of VTE suggests an important role of surgical duration in the postoperative assessment of VTE risk,” the authors continued. “Our findings suggest that risk assessment should factor in the length of surgery more thoroughly.”

The results of the study were even true when the researchers analyzed the data in an effort to minimize the effects of outliers, concurrent complications, procedural differences, and unmeasured confounding variables.

“The recent implementation of the Patient Protection and Affordable Care Act continues to pressure physicians to reduce post operative complications that drive readmissions and contribute to high health care costs. Because VTE is responsible for more than 500, 000 hospitalizations annually, quantifying its risk is valuable to both improving the quality and reducing the cost of patient care,” the authors concluded.