Adverse Impact of Obesity on Lumbar Spine Fusion, Patient-Reported Outcomes and Costs: A Systematic Review and Meta-Analysis

John E O'Toole; Rick C Sasso; James S Harrop; Gonzalo Mariscal; Christopher D Chaput; Paul M Arnold; Christopher D Witiw; W Bradley Jacobs; Michael P Steinmetz

doi:10.1097/BRS.0000000000005395

Adverse Impact of Obesity on Lumbar Spine Fusion, Patient-Reported Outcomes and Costs: A Systematic Review and Meta-Analysis

Spine (Phila Pa 1976). 2025 May 28. doi: 10.1097/BRS.0000000000005395. Online ahead of print.

Authors

John E O'Toole¹, Rick C Sasso², James S Harrop³, Gonzalo Mariscal⁴, Christopher D Chaput⁵, Paul M Arnold⁶, Christopher D Witiw⁷, W Bradley Jacobs⁸, Michael P Steinmetz⁹

Affiliations

¹ Rush University Medical Center, Chicago, Illinois, US.
² Dept Orthopaedic Surgery, Indiana University School of Medicine, Indiana Spine Group, Carmel, Indiana, US.
³ Departments of Neurological and Orthopedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, US.
⁴ Institute for Research on Musculoskeletal Disorders, Valencia Catholic University, Valencia, ES.
⁵ Department of Orthopedics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, US.
⁶ Department of Neurological Surgery, Loyola University Chicago, Chicago, Illinois, US.
⁷ Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, CA.
⁸ Calgary Spine Program, Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, CA.
⁹ Neurological Institute, Department of Neurosurgery, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio, US.

PMID: 40433998
DOI: 10.1097/BRS.0000000000005395

Abstract

Study design: Systematic review and meta-analysis.

Purpose: The objective of this study is to determine the impact of obesity on three key lumbar spinal surgery outcomes: the incidence of spinal nonunion, patient-reported outcome measures (PROMs), and the associated healthcare costs.

Summary of background data: Obesity is a well-recognized risk factor in various medical fields, notably impacting outcomes in orthopedics and traumatology. While there is substantial documentation of the complications associated with obesity in general surgical procedures, the relationship between obesity and spinal surgery outcomes remains less clear. The inconsistency in the evidence presents a significant gap in our understanding of how obesity influences the results of spinal surgeries, particularly in terms of nonunion rates, patient-reported outcomes, and the associated healthcare costs.

Methods: A systematic search was conducted in PubMed, EMBASE, Scopus, and the Cochrane Library following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Studies comparing patients with or without obesity with lumbar spinal fusion were included. Comparative studies (cohort and case-control) were included. For dichotomous variables such as spinal nonunion, analysis was conducted using odds ratios (OR); for continuous variables such as PROMs (Oswestry Disability Index (ODI), Visual Analogue Scale (VAS), and 12/36-Item Short Form Survey (SF-12/36), and costs, analyses were performed using mean differences (MD) or standardized mean differences (SMD).

Results: Fifteen studies with a pool of 61341 patients were included. Obesity (BMI≥30) was significantly associated with a higher nonunion frequency (OR 2.10, 95%CI 1.23 to 3.60, P <0.01). The ODI was significantly worse in the obesity group (MD 6.29, 95% CI 4.71 to 7.88, P <0.001). Greater pain was measured by the VAS back pain (MD 0.95, 95% CI 0.17 to 1.73, P <0.05) and VAS leg pain (MD 0.94, 95% CI 0.68 to 1.20, P <0.001) scales for lumbar surgery patients with obesity. The SF-12/36 showed significantly worse outcomes in patients with obesity (SMD -0.46, 95%CI -0.82 to -0.09, P =0.01). Hospitalization costs were significantly higher in patients with obesity (SMD 0.09, 95%CI 0.05 to 0.12, P <0.001).

Conclusion: This meta-analysis suggests that obesity is significantly associated with higher nonunion rates, poorer patient-reported outcome measures including Oswestry Disability Index, Visual Analogue Scale, and 36-Item Short Form Survey, and higher hospitalization costs following lumbar spinal fusion.

Level of evidence: III.

Keywords: costs; meta-analysis; nonunion; obesity; patient-reported outcomes; spinal fusion.