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Identifying Patients at High Risk for Venous Thromboembolism Requiring Treatment After Outpatient Surgery

Pannucci, Christopher J. MD, MS*; Shanks, Amy MS; Moote, Marc J. PA-C; Bahl, Vinita DMD, MPP§; Cederna, Paul S. MD*; Naughton, Norah N. MD; Wakefield, Thomas W. MD; Henke, Peter K. MD; Campbell, Darrell A. MD; Kheterpal, Sachin MD, MBA

doi: 10.1097/SLA.0b013e3182519ccf
Original Articles

Objective: To identify independent predictors of 30-day venous thromboembolism (VTE) events requiring treatment after outpatient surgery.

Background: An increasing proportion of surgical procedures are performed in the outpatient setting. The incidence of VTE requiring treatment after outpatient surgery is unknown.

Methods: Prospective observational cohort study using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2005 to 2009. Adult patients who had outpatient surgery or surgery with subsequent 23-hour observation were included. The main outcome measure was 30-day VTE requiring treatment. Patients were randomly assigned to derivation (N = 173,501) or validation (N = 85,730) cohorts. Logistic regression examined independent risk factors for 30-day VTE. A weighted risk index was created and applied to the validation cohort. Stratified analyses examined 30-day VTE by risk level.

Results: Thirty-day incidence of VTE for the overall cohort was 0.15%. Independent risk factors included current pregnancy (adjusted odds ratio [OR] = 7.80, P = 0.044), active cancer (OR = 3.66, P = 0.005), age 41 to 59 years (OR = 1.72, P = 0.008), age 60 years or more (OR = 2.48, P < 0.001), body mass index 40 kg/m2 or higher (OR = 1.81, P = 0.015), operative time 120 minutes or more (OR = 1.69, P = 0.027), arthroscopic surgery (OR = 5.16, P < 0.001), saphenofemoral junction surgery (OR = 13.20, P < 0.001), and venous surgery not involving the great saphenous vein (OR = 15.61, P < 0.001). The weighted risk index identified a 20-fold variation in 30-day VTE between low (0.06%) and highest risk (1.18%) patients.

Conclusions: Thirty-day VTE risk after outpatient surgery can be quantified using a weighted risk index. The risk index identifies a high-risk subgroup of patients with 30-day VTE rates of 1.18%.

Supplemental Digital Content is available in the text.The authors performed a prospective observational cohort study using ACS-NSQIP (American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) data to examine 30-day venous thromboembolism (VTE) after outpatient surgery. A weighted risk index was created and subsequently validated. The risk index identified a 20-fold variation in 30-day VTE between low (0.06%) and the highest (1.18%) risk patients.

*Section of Plastic Surgery

Department of Anesthesiology

Office of Clinical Affairs

§Clinical Information and Decision Support Services

Section of Vascular Surgery, University of Michigan.

Reprints: Christopher J. Pannucci, MD, MS, Section of Plastic Surgery, Department of Surgery, University of Michigan, 2130 Taubman Center, SPC 5340, 1500 East Medical Center Drive, Ann Arbor, MI 48105. E-mail:

Disclosure: Dr Pannucci receives salary support through NIH grant T32 GM-08616. The remaining authors have nothing to disclose.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (

© 2012 Lippincott Williams & Wilkins, Inc.