DVT, PE risk increased in surgery patients with IBD

October 18, 2011

BY SHARON WORCESTER

Patients with inflammatory bowel disease who undergo surgery have a twofold increase in the risk of deep vein thrombosis or pulmonary embolism, compared with those without IBD, and the risk is even greater among those with IBD who undergo nonintestinal surgery, according to findings from the American College of Surgeons National Surgical Quality Improvement Program.

In a retrospective cohort study of nearly 269,000 patients from the National Surgical Quality Improvement Program (NSQIP) 2008, 2,249 (0.8%) had IBD. Deep vein thrombosis (DVT) or pulmonary embolism (PE) occurred in 1% of those without IBD, in 2.5% of those with IBD, and in 5% of those with IBD who underwent nonintestinal surgery.

Dr. Andrea Merrill of Massachusetts General Hospital and Dr. Frederick Millham of Newton Wellesley Hospital, both in Boston, reported the research online in the Oct. 17 issue of Archives of Surgery. The findings suggest that the standard DVT and PE prophylaxis for patients undergoing surgery should be reconsidered for those with IBD, they concluded.

After adjustment for more than 30 possible confounders available in the NSQIP that add to the power to predict DVT or PE, a significant association remained between IBD and DVT or PE overall (odds ratio, 2.03) and among those undergoing nonintestinal surgery (OR, 4.45), the investigators found (Arch. Surg. 2011 Oct. 17 [doi:10.1001/archsurg.2011.297]).

No difference was seen between the patients with and without IBD in regard to the occurrence of cerebrovascular accident or myocardial infarction, with 0.4% of patients in both groups experiencing such events.

Although IBD has long been known to be associated with an increased risk of thromboembolic events, data on those undergoing surgery has been scarce, and standard DVT and PE prophylaxis guidelines in the IBD population have not been adjusted to include enhanced prophylaxis.

In light of one recent study suggesting a very high risk of postoperative DVT in those undergoing surgery, the investigators sought to evaluate the risk among IBD patients in the NSQIP, which collected data from 170 hospitals in 2008, resulting in a Participant Use Data File (PUF). The de-identified research database is made available to the participating hospitals.

“As such, the NSQIP PUF data set presents an opportunity to examine the relationship of DVT and PE with IBD in a large group of patients for whom data on comorbid conditions and other potential confounding variables are available and well defined. Furthermore, hospitals participating in the NSQIP, having invested in quality improvement, might be expected to treat patients with best practices, at least with respect to DVT prophylaxis,” the investigators said, explaining that this would reduce the opportunity for treatment bias between centers.

The finding of an increased risk of DVT or PE in IBD patients was consistent with others in both surgical and nonsurgical IBD patients, they found.

An exception is with the lethality of DVT or PE in the setting of IBD. One prior study demonstrated an increased risk of death among IBD patients with DVT or PE, but the investigators of the current study found no support for this finding. Mortality occurred in 8.6% and 8.8% of those without IBD who had DVT or PE, and those with IBD who had DVT or PE, respectively.

They also found no support for one prior study’s finding of an increased risk of arterial thromboembolic events in patients with IBD, but they noted that the current study may have been limited by the lack of data on arterial thrombotic events not involving the coronary or cerebral vessels.

“It may be that if arterial thromboembolism were a reported NSQIP complication, such a relationship would appear,” they said.

Although this study is limited by the fact that the NSQIP was designed to compare overall outcomes across many hospitals rather than to answer specific research questions regarding specific diseases or procedures, its strengths – namely the fact that the data were gathered by specially trained nurses who were accountable to a rigid quality-assurance program, and who were working from a well-defined data dictionary – likely outweigh any potential sources of bias, they said.

The authors reported that they had no disclosures.