Introduction: Obesity, a growing global public health concern, has been linked to medical and surgical complications in orthopedics and traumatology. Existing evidence on the association of obesity and spinal surgery is inconsistent, highlighting the need for a pooled meta-analysis. This study aimed to assess the impact of obesity on incidence of spinal nonunion, patient-reported outcome measures (PROMs) and costs.
Methods: A systematic search was conducted in four databases. Studies comparing obesity versus non-obesity in patients undergoing spinal fusion surgeries were included. The primary outcomes of interest were the incidence of spinal non-union, PROMs and costs. Odds ratios (OR) were calculated for dichotomous variables and mean differences (MD) or standard mean differences (SMD) were calculated for continuous variables. Meta-analysis was performed using RevMan 5.4 software, with random effects applied in the presence of heterogeneity.
Results: 34 studies (n=433993) were included. Obesity (BMI≥30) was significantly associated with a higher nonunion frequency (OR 2.10, 95%CI 1.23-3.60; p=0.007). The ODI was significantly worse in the obesity group (MD 5.45, 95%CI 3.28 to 7.63). Pain measured by the VAS back pain and VAS leg pain scales, patients with obesity presented greater pain in the case of lumbar surgery: (MD 0.95, 95%CI 0.17 to 1.73) and (MD 0.94, 95%CI 0.68 to 1.20) respectively. The SF-36 PCS showed significantly worse outcomes in patients with obesity (MDS -0.46, 95%CI -0.82 to -0.09). Hospitalization costs were significantly higher in patients with obesity (MDS -0.09, 95%CI -0.12 to -0.07). Patients with obesity also had a significant increase in the cost per QALY (MDS -1.49, 95%CI -1.74 to -1.24).
Conclusion : This meta-analysis suggests obesity is significantly associated with higher nonunion rates, poorer PROMs including ODI, VAS, and SF-36 scores, increased hospitalization costs and higher cost per QALY following spinal fusion, confirming obesity as a factor impairing surgical outcomes.