The influence of body mass index obesity status on vascular surgery 30-day morbidity and mortality

Daniel L. Davenport, Eleftherios S. Xenos, Patrick Hosokawa, Jacob Radford, William G. Henderson, Eric D. Endean

Research output: Contribution to journalArticlepeer-review

201 Scopus citations

Abstract

Objective: Mild obesity may have a protective effect against some diseases, termed an "obesity paradox." This study examined the effect of body mass index (Kg/m2 BMI) on surgical 30-day morbidity and mortality in patients undergoing vascular surgical procedures. Methods: As part of the National Surgical Quality Improvement Program (NSQIP), demographic and clinical risk variables, mortality, and 22 defined complications (morbidity) were obtained over three years from vascular services at 14 medical centers. At each medical center, patients from the operative schedule were prospectively and systematically enrolled according to NSQIP protocols. Outcomes and risk variables were compared across NIH-defined obesity classes (underweight [BMI≤18.5], normal [18.5<BMI<25], overweight [25<BMI≤30], obese I [30<BMI≤35], obese II [35<BMI≤40], and obese III [BMI>40]) using analysis of variance and means comparisons. Logistic regression was used to control for other risk factors. Results: Vascular procedures in 7,543 patients included lower extremity revascularization (24.6%), aneurysm repair (17.4%), cerebrovascular procedures (17.3%), amputations (9.4%), and "other" procedures (31.3%). In the entire cohort, there were 1,659 (22.0%) patients with complications and 295 (3.9%) deaths. Risk factors of hypertension and diabetes increased with BMI (analysis of variance [ANOVA] P < .05) as expected; smoking, disseminated cancer, and stroke decreased (ANOVA P < .01). Twenty other risk factors, as well as mortality and morbidity, had "U" or "J"-shaped distributions with the highest incidence in underweight and/or obese class III extremes but reduced minimums in overweight or obese I classes (ANOVA P < .05). After controlling for age, gender, and operation type, mortality risk remained lowest in obese class I patients (Odds ratio [OR] 0.63, P = .023) while morbidity risk was highest in obese class III patients (OR 1.70, P = .0003), due to wound infection, thromboembolism, and renal complications. Conclusion: Underweight patients have poorer outcomes and class III obesity is associated with increased morbidity. Mildly obese patients have reduced co-morbid illness, surprisingly even less than normal-class patients, with correspondingly reduced mortality. Mild obesity is not a risk factor for 30-day outcomes after vascular surgery and confers an advantage.

Original languageEnglish
Pages (from-to)140-147.e1
JournalJournal of Vascular Surgery
Volume49
Issue number1
DOIs
StatePublished - Jan 2009

Bibliographical note

Funding Information:
The data used in this study were generated by the “Reporting System to Improve Patient Safety in Surgery Study” funded by the U.S. Agency for Healthcare Research and Quality, Rockville, MD, under Grant #5U18HS011913.

ASJC Scopus subject areas

  • Surgery
  • Cardiology and Cardiovascular Medicine

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