Social Vulnerability Index Provides Greater Granularity Compared to the Area Deprivation Index When Assessing Outcomes Following Elective Lumbar Fusion

Study Design. Retrospective review of a single institution cohort. Objective. To determine whether area deprivation index (ADI) or social vulnerability index (SVI) is more suitable for evaluating minimum clinically important difference (MCID) achievement following elective lumbar fusion as captured by the Patient-Reported Outcomes Measurement Information System (PROMIS). Summary of Background Data. A total of 182 patients who underwent elective one-level to two-level posterior lumbar fusion between January 2015 and September 2021. Materials and Methods. ADI and SVI values were calculated from patient-supplied addresses. Patients were grouped into quartiles based on values; higher quartiles represented greater disadvantage. MCID thresholds for Pain Interference (PI) and Physical Function (PF) were determined through a distribution-based method. Multivariable logistic regression was performed to identify factors impacting MCID attainment. Univariate logistic regression was performed to determine which themes comprising SVI values affected MCID achievement. Statistical significance was set at P <0.05. Results. Multivariable logistic regression demonstrated that ADI and SVI quartile assignment significantly impacted achievement of MCID for PI ( P =0.04 and 0.01, respectively) and PF ( P =0.03 and 0.02, respectively). Specifically, assignment to the third ADI and SVI quartiles were significant for PI (OR: 0.39 and 0.23, respectively), and PF (OR: 0.24 and 0.22, respectively). Race was not a significant predictor of MCID for either PI or PF. Univariate logistic regression demonstrated that among SVI themes, the socioeconomic status theme significantly affected achievement of MCID for PI ( P =0.01), while the housing type and transportation theme significantly affected achievement of MCID for PF ( P =0.01). Conclusion. ADI and SVI quartile assignment were predictors of MCID achievement. While ADI and SVI may both identify patients at risk for adverse outcomes following lumbar fusion, SVI offers greater granularity in terms of isolating themes of disadvantage impacting MCID achievement.