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30-04-2012 | Cardiology | Article

Weighted risk index identifies patients at high VTE risk after surgery


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MedWire News: A weighted risk index can be used to identify patients who are at an increased risk for venous thromboembolism (VTE) after outpatient surgery, a study shows.

"The risk index provides excellent discrimination between high- and low-risk patients," write Christopher Pannucci (University of Michigan, Ann Arbor, USA) and co-authors in the Annals of Surgery.

Their prospective observational cohort study used data from the American College of Surgeons National Surgical Quality Improvement Program database between 2005 and 2009. It included adult patients who had outpatient surgery or surgery with subsequent 23-hour observation.

All patients were randomly allocated to a derivation (n=173,501) or validation (n=85.730) cohort and were assessed for VTE requiring treatment within 30 days.

The 30-day incidence of VTE for the overall cohort was 0.15%. Independent risk factors for this outcome included current pregnancy (odds ratio [OR]=7.80), active cancer (OR=3.66), and age 41-59 years (OR=1.72 vs <40 years).

Age 60 years or more (OR=2.48 vs <40 years), body mass index of at least 40 kg/m2 (OR=1.81 vs <25 kg/m2), and operative time of 120 minutes or more (OR=1.69 vs <60 minutes) were also predictors for 30-day VTE requiring treatment.

Other predictors included arthroscopic surgery (OR=5.16), saphenofemoral junction surgery (OR=13.20), and venous surgery not involving the great saphenous vein (OR=15.61).

The weighted risk index identified a 20-fold variation in 30-day VTE risk between low risk (<0.1%) and highest risk (≤1.2%) patients.

"We have observed that 'highest risk' patients undergoing outpatient surgery have an almost 20-fold increase in risk of VTE requiring therapy," write the authors.

"Further research is necessary to create a comprehensive risk model for outpatient surgery patients by combining our risk index with other recognized VTE risk factors."

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

By Piriya Mahendra

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