Analyzing the relationship between the social vulnerability index and 90-day elective lumbar fusion outcomes

The social vulnerability index (SVI) is a centers for disease control and prevention (CDC) census data tool to identify populations that are susceptible to hazards and health emergencies. Higher scores indicate more socioeconomic vulnerability. There is a scarcity of studies investigating the relationship of SVI on spine surgery outcomes.

To determine an association between overall SVI scores and postoperative outcomes with elective lumbar fusions.

Retrospective review.

A total of 1,064 adults aged 18 to 85 years who underwent elective lumbar fusion surgery between January 1, 2013, and June 30, 2023, at a Level 1 trauma center in Southern California. Patients were categorized into low, moderate, and high social vulnerability groups based on their SVI.

Ninety-day outcome measures were categorized by systemic outcomes, infectious complications, pulmonary complications, and cardiac complications. Systemic outcomes measured were length of stay and readmission. Infectious complications measured were sepsis, urinary tract infection, and surgical site infection. Pulmonary complications measured were mechanical ventilation, respiratory failure, and pneumonia. Cardiac complications measured were cardiac arrest, cerebrovascular event, deep vein thrombosis, hemodynamic instability, and need for transfusion.

Demographic and clinical outcomes were obtained and reviewed by an analytics team utilizing CPT/ICD codes corresponding to diagnoses or outcomes found in each patient's chart. SVI was obtained using the CDC census tract data available on the CDC website. Patients were categorized into 3 cohorts based on their overall SVI scores-Low (<16th percentile), Moderate (16th to 84th percentile), and High (>84th percentile). Statistical analyses across the 3 SVI cohorts were conducted using chi-square and Fisher's exact tests for categorical variables and Kruskal-Wallis test for continuous variables. Posthoc, inter-SVI group statistics were run with Dunn's test with Bonferroni correction for continuous variables and pairwise Chi-square tests with Bonferroni correction for categorical variables.

A total of 1,064 patients were included for analysis. Demographically, White or Caucasian ethnicity (p=.004) is correlated with the lower SVI group, while Hispanic ethnicity is correlated with higher SVI scores (p<.001). Alcohol use was associated with lower SVI (p=.015), while drug use trended with higher SVI, but was not significant (p=.071). Clinically, patients in the high SVI group had significantly longer lengths of stay (p=.001), and potentially higher rates of respiratory failure (p=.011), and more cardiac arrests (p=.011). Compared to the medium SVI group, the high SVI group showed a trend toward increased pulmonary complications after posthoc correction (p=.077).

Higher SVI scores are significantly associated with adverse postoperative outcomes following elective lumbar fusion surgery. Specifically, increased SVI scores correlate with prolonged hospitalization and may also lead to a higher incidence of pulmonary complications and cardiac arrest. These findings highlight the clinical relevance of incorporating SVI assessments into preoperative risk evaluations, emphasizing the need for targeted interventions and resource allocation strategies tailored toward socially vulnerable populations. By addressing these socioeconomic disparities proactively, healthcare providers can enhance patient care, reduce postoperative complications, and improve overall healthcare equity in spine surgery populations.