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Prolonged surgery increased risk for VTE
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Longer duration of surgery directly correlated with risk for venous thromboembolism, according to results of a retrospective study.
“As VTEs have been designated a ‘never’ event by the Center for Medicare and Medicaid Services (CMS), it is critical that we as clinicians understand the risk factors and potential causative etiologies for VTEs,” John Y.S. Kim, MD, of the department of surgery at Northwestern University’s Feinberg School of Medicine, told HemOnc Today. “This study looked at over 1.3 million patients to establish that surgical duration is an independent predictor of VTE.”
The association between longer surgical procedures and morbidity — including VTE — has been widely accepted, but it has never been addressed quantitatively. Because more than 500,000 hospitalizations and 100,000 deaths annually are associated with VTE, a thorough examination of the link between them and the length of surgical procedures could allow for better-informed surgical decisions, researchers suggested.
Kim and colleagues reviewed data on more than 1.4 million patients who underwent surgery with general anesthesia at 315 US hospitals that participated in the American College of Surgeons National Surgical Quality Improvement Program between 2005 and 2011.
In this cohort, 13,809 patients (0.96%) developed a post-operative VTE, 10,198 patients (0.71%) developed a deep vein thrombosis, and 4,772 patients (0.33%) developed a pulmonary embolism.
Researchers observed a “stepwise” association between surgical duration and VTE incidence. Patients who underwent the longest procedures demonstrated 1.27-fold (95% CI, 1.21-1.34; adjusted risk difference [ARD], 0.23%) increase in risk for VTE. Among those who underwent the shortest procedures, the odds ratio for VTE was 0.86 (95% CI, 0.83-0.88; ARD, -0.12%).
Researchers standardized surgical times using a Z-score and putting them on a bell curve of five quintiles, with the first quintile representing the shortest procedures, the third quintile representing average-length procedures and the fifth quintile representing the longest procedures.
The middle 20% of the procedures, based on average surgical times, demonstrated a VTE rate of 0.86% (95% CI, 0.83-0.90). Shorter procedures in the first and second quintile carried ORs of 0.86 (95% CI, 0.83-0.88; ARD, -0.12%) and 0.98 (95% CI, 0.95-1; ARD, -0.02%), respectively. Conversely, longer surgeries in the fourth and fifth quintiles carried ORs of 1.1 (95% CI, 1.07-1.13; ARD, 0.09%) and 1.27 (95% CI, 1.21-1.34; ARD, 0.23%), respectively.
The association between VTE incidence and the longest surgery times was significant in 82% of 1,000 bootstrap samples, Kim and colleagues wrote.
Researchers observed similar trends for DVTs and PEs.
Multiple sensitivity analyses designed to limit the effect of procedural differences, concurrent complications, outliers and other confounding variables supported “the robustness of these results,” Kim and colleagues wrote.
The analysis included nine surgical specialties: general, urologic, gynecologic, orthopedic, vascular, cardiothoracic, otolaryngologic, plastic and neurologic. The incidence of VTE increased with the longer-duration surgeries in all nine surgical specialties (P<.05).
Otolaryngologic procedures had the lowest incidence of VTE (0.11% in the shortest procedures, 0.67% in the longest operations). Cardiothoracic procedures (1.44% in the shortest, 3.49% in the longest) and neurologic procedures (1.04% in the shortest, 2.86% in the longest) had the greatest incidence of VTE.
“This basic relationship held across surgical disciplines as varied as neurosurgery and gynecologic surgery and held true within given procedures,” Kim said.
Improved understanding of the relationship between surgical duration and VTE can better direct surgical planning and management, researchers wrote. It also can help physicians, surgeons and anesthesiologists plan chemoprophylaxis strategies, as well as better inform clinicians and patients about the potential risks of prolonged surgery, they said.
“Going forward, we may want to consider adopting strategies to limit surgical time and instituting appropriate chemoprophylaxis regimens for longer surgeries” Kim told HemOnc Today. “We may also wish to incorporate surgical duration in more precise fashion into current risk stratification schemes.”
Disclosure: The researchers report no relevant financial disclosures.
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