Mild and Severe Obesity Reduce the Effectiveness of Lumbar Fusions: 1-Year Patient-Reported Outcomes in 8171 Patients

Abstract

BACKGROUND: Elevated body mass index (BMI) is a well-known risk factor for surgical complications in lumbar surgery. However, its effect on surgical effectiveness independent of surgical complications is unclear. OBJECTIVE: To determine increasing BMI's effect on functional outcomes following lumbar fusion surgery, independent of surgical complications. METHODS: We retrospectively analyzed a prospectively built, patient-reported, quality of life registry representing 75 hospital systems. We evaluated 1- to 3-level elective lumbar fusions. Patients who experienced surgical complications were excluded. A stepwise multivariate regression model assessed factors independently associated with 1-yr Oswestry Disability Index (ODI), preop to 1-yr ODI change, and achievement of minimal clinically important difference (MCID). RESULTS: A total of 8171 patients met inclusion criteria: 2435 with class I obesity (BMI 30-35 kg/m2), 1328 with class II (35-40 kg/m2), and 760 with class III (≥40 kg/m2). Increasing BMI was independently associated with worse 12-mo ODI (t = 8.005, P