(HealthDay News) – Using a weighted risk index, the highest-risk outpatient surgery patients have an almost 20-fold increase in risk of venous thromboembolism (VTE) requiring therapy.

Christopher J. Pannucci, MD, from the University of Michigan in Ann Arbor, and colleagues analyzed data from an observational cohort study using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database (2005–2009). Adult outpatient surgery or surgery with subsequent 23-hour observation patients (259,231 total participants) were included.

The researchers found that, overall, 30-day incidence of VTE was 0.15%. Risk factors that independently increased the risk of VTE were current pregnancy (adjusted odds ratio [OR], 7.8), active cancer (OR, 3.66), age 41–59 years (OR, 1.72), age ≥60 years (OR, 2.48), body mass index ≥40kg/m² (OR, 1.81), operative time ≥120 minutes (OR, 1.69), arthroscopic surgery (OR, 5.16), saphenofemoral junction surgery (OR, 13.2), and venous surgery not involving the great saphenous vein (OR, 15.61). There was a 20-fold difference in 30-day VTE between lowest- and highest-risk patients (0.06 and 1.18%, respectively) using a weighted risk index.

“Thirty-day VTE risk after outpatient surgery can be quantified using a weighted risk index,” the authors write.

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