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Obesity as protective against, rather than a risk factor for, postoperative Clostridium difficile infection

A nationwide retrospective analysis of 1,426,807 surgical patients

Meier, Karien MSc; Nordestgaard, Ask T. BSc; Eid, Ahmed I. MD; Kongkaewpaisan, Napaporn MD; Lee, Jae M. BA; Kongwibulwut, Manansun MD; Han, Kelsey R. AB; Kokoroskos, Nikolaos MD; Mendoza, April E. MD, MPH; Saillant, Noelle MD; King, David R. MD; Velmahos, George C. MD, PhD; Kaafarani, Haytham M.A. MD, MPH

Journal of Trauma and Acute Care Surgery: June 2019 - Volume 86 - Issue 6 - p 1001–1009
doi: 10.1097/TA.0000000000002249

BACKGROUND Recent studies suggest that obesity is a risk factor for Clostridium difficile infection, possibly due to disruptions in the intestinal microbiome composition. We hypothesized that body mass index (BMI) is associated with increased incidence of C. difficile infection in surgical patients.

METHODS In this nationwide retrospective cohort study in 680 American College of Surgeons National Surgical Quality Improvement Program participating sites across the United States, the occurrence of C. difficile infection within 30 days postoperatively between different BMI groups was compared. All American College of Surgeons National Surgical Quality Improvement Program patients between 2015 and 2016 were classified as underweight, normal-weight, overweight, or obese class I-III if their BMI was less than 18.5, 18.5 to 25, 25 to 30, 30 to 35, 35 to 40 or greater than 40, respectively.

RESULTS A total of 1,426,807 patients were included; median age was 58 years, 43.4% were male, and 82.9% were white. The postoperative incidence of C. difficile infection was 0.42% overall: 1.11%, 0.56%, 0.39%, 0.35%, 0.33% and 0.36% from the lowest to the highest BMI group, respectively (p < 0.001 for trend). In univariate then multivariable logistic regression analyses, adjusting for patient demographics (e.g., age, sex), comorbidities (e.g., diabetes, systemic sepsis, immunosuppression), preoperative laboratory values (e.g., albumin, white blood cell count), procedure complexity (work relative unit as a proxy) and procedure characteristics (e.g., emergency, type of surgery [general, vascular, other]), compared with patients with normal BMI, high BMI was inversely and incrementally correlated with the postoperative occurrence of C. difficile infection. The underweight were at increased risk (odds ratio, 1.15 [1.00–1.32]) while the class III obese were at the lowest risk (odds ratio, 0.73 [0.65–0.81]).

CONCLUSION In this nationwide retrospective cohort study, obesity is independently and in a stepwise fashion associated with a decreased risk of postoperative C. difficile infection. Further studies are warranted to explore the potential and unexpected association.

LEVEL OF EVIDENCE Prognostic/Epidemiologic, Level IV.

From the Division of Trauma, Emergency Surgery, and Surgical Critical Care, Department of Surgery (K.M., A.T.N., A.I.E., N.K., J.M.L., M.K., K.R.H., N.K., A.E.M., N.S., D.R.K., G.C.V., H.M.A.K.), Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, Department of Trauma Surgery (K.M.), Leiden University Medical Center, Leiden University, The Netherlands; and Department of Anaesthesia (A.T.N.), Centre of Head and Orthopaedics, Rigshospitalet, University of Copenhagen, Denmark.

Submitted: January 17, 2019, Revised: February 15, 2019, Accepted: March 2, 2019, Published online: March 11, 2019.

Address for reprints: Haytham M.A. Kaafarani, MD, Division of Trauma, Emergency Surgery and Surgical Critical Care, Massachusetts General Hospital, 165 Cambridge Street, Suite 810, Boston, MA 02114; email:

Winner of the Massachusetts Committee on Trauma (COT) Resident Trauma Paper Competition (oral presentation, November 2018).

Winner of the Region 1 COT Resident Trauma Paper Competition (oral presentation, December 2018).

Poster of Distinction at the 65th Annual Meeting during the Massachusetts Chapter of the American College of Surgeons (December 2018).

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© 2019 Lippincott Williams & Wilkins, Inc.