WASHINGTON – Cardiac and vascular surgery patients are at higher risk for deep vein thrombosis than are general surgery patients, according to data presented at the annual clinical congress of the American College of Surgeons.
In a retrospective analysis of 2,669,772 patients with a median age of 64 years, 43% of whom were males, in the ACS-National Surgery Quality Improvement Program (NSQIP) during 2005-2009, Dr. Faisal Aziz of Penn State Hershey (Pa.) Heart and Vascular Institute and his colleagues sought to determine the actual rate of deep vein thrombosis (DVT) during revascularization procedures, compared with general surgery. They also investigated the relationship between the type of operation and the DVT incidence rate.
The Agency for Healthcare Research and Quality considers the incidence rate of DVT a patient safety indicator. Dr. Aziz cited data indicating that one in four patients who develop DVT postoperatively before discharge has an additional venous thromboembolic event–related event in the subsequent 21 months requiring hospitalization, at a cost of approximately $15,000, or roughly 21% higher than the original DVT event (J. Manag. Care. Pharm. 2007;13:475-86).
The researchers sorted patients according to DVT risk factors such as age, gender, body mass index over 40 kg/m2, and whether the surgery was acute. They then assessed intraoperative factors such as total time to completion and its American Society of Anesthesiology score. They then considered the postoperative factors associated with DVT, such as blood transfusions, return to the operating room, deep wound infection, cardiac arrest, and mortality.
Dr. Aziz and his team determined that there were 18,512 incidences of DVT, equaling 0.69% of all patients studied. Of those, 0.66% occurred during general surgery, 2.08% occurred during cardiac surgery, and 1% occurred during vascular surgery.
"The implications of our study are that, contrary to popular belief, the incidence of postoperative DVT is actually higher after cardiac surgery and vascular surgery procedures," he said.
The cardiac surgery procedures associated with the highest DVT incidence rate were tricuspid valve replacement (8%), thoracic endovascular aortic repair (5%), thoracic aortic graft replacement (4%), and pericardial window (4%).
In a comparison of cardiac procedures, tricuspid valve replacement vs. aortic valve replacement had a risk ratio of 3.5 (P < .001). In tricuspid valve replacement vs. coronary artery bypass, the former had a risk ratio of 11.24 (P < .001).
Vascular surgeries with the highest DVT incidence rates were peripheral bypass (1%), amputation (trans-metatarsal, 0.75%; below knee, 1%; above the knee, 1%), and ruptured aortic aneurysms (3.5%), Dr. Aziz reported.
Intra-and postoperative factors associated with DVT risk included operation times exceeding 240 minutes and previous DVT. Compared with 21% of general surgery patients, operation time was implicated in 59% of cardiac surgery patients (relative risk, 2.72; P < .001) and 25% of vascular surgery patients (RR, 1.14; P <.001). Blood transfusions affected 13% of cardiac surgery patients (RR, 2.3; P < .001), 6% of vascular surgery patients (RR, 1.3; P < .001), and 6% of general surgery patients.
Compared with 24% for general surgery patients, returning to the operating room was implicated in 27% of cardiac patients (RR, 1.4; P = .27) and 32% of vascular surgery patients (RR, 1.3; P < .001).
"Procedures and perioperative factors associated with high risk of postoperative DVT should be identified, and adequate DVT prophylaxis should be ensured for these patients," he concluded.
Dr. Aziz and his associates had no disclosures.