Rice O, Patt JC, Asher AL, et al. - we aim to determine whether increasing BMI is associated with worse functional outcomes independent of surgical complications. Researchers retrospectively examined a prospective, nationwide, patient-reported quality-of-life registry to ascertain whether increasing BMI is associated with worse functional outcomes independent of surgical complications. They applied a stepwise multivariate regression model to evaluate patient-specific factors independently correlated with outcome measures defined below. A prospective, nationwide, patient-reported quality-of-life registry representing 75 hospital systems was examined for patients who received elective 1- to 3-level lumbar fusion for stenosis and spondylolisthesis. Factors independently associated with 12-month Oswestry Disability Index (ODI) score, preop to 12-month ODI change score, and achievement of MCID (14.3-point ODI improvement) were evaluated by using a stepwise multivariate regression model The study population consisted of 8,171 patients. The results demonstrate that elevating BMI was independently correlated with a worse pain-related disability and decreased effectiveness of surgery despite lack of surgical complication one year after elective 1- to 3-level lumbar fusion. It was shown that BMI 30-35 was also associated with reduced surgical effectiveness, while the effectiveness of surgery was significantly reduced in Class 3 obesity (BMI ≥ 40.0). The outcomes revealed that BMI as low as 30-35 may represent a modifiable risk factor for decreased effectiveness/value of lumbar fusion.