BMI and Patient-Reported Outcomes Following Spinal Surgery: A Retrospective Review.

OBJECTIVE

Body mass index (BMI) plays an important role in surgical outcomes following spinal fusion surgery, with increasing BMI linked to greater risk of post-operative complications. However, the relationship between BMI and long-term patient-reported outcome measures (PROMs) lacks investigation. This study aims to evaluate the association between patient BMI and PROMs in patients undergoing spinal fusion surgery.

METHODS

A retrospective analysis was conducted on patients who underwent spinal fusion surgery at a single academic institution between 2016 and 2024. Demographic, surgical, and PROM data were extracted from existing medical records. Multivariable linear regression models were implemented to control for potential confounders.

RESULTS

A total of 1471 patients undergoing spinal fusion were included. Obese patients were younger and had a higher prevalence of diabetes and hypertension compared with other BMI groups. Mean ODI, NDI, VAS Neck, VAS Back, and PROMIS Pain scores differed significantly across BMI categories over 12 months, whereas VAS Arm and VAS Leg did not. In multivariable linear models adjusting for time, demographics, surgical factors, and comorbidities, obesity independently predicted worse ODI, VAS Arm, and VAS Leg scores, and overweight status predicted worse VAS Leg scores. However, BMI was not a consistent independent predictor of MCID achievement across PROMs. Time from surgery, female sex, longer operative duration, greater number of levels fused, and revision status were more robust predictors of both absolute PROM scores and MCID achievement than BMI category.

CONCLUSIONS

In this large ERAS-based spinal fusion cohort, elevated BMI was associated with significantly worse mean pain and disability scores but did not consistently predict clinically meaningful improvement. Recovery was more strongly influenced by time from surgery, surgical complexity, and demographic factors rather than BMI alone. These findings suggest BMI should not be used in isolation to determine postoperative expectations and support individualized perioperative optimization.