Community-level Socioeconomic Status is a Poor Predictor of Outcomes Following Lumbar and Cervical Spine Surgery

Study design: Retrospective Cohort study.

Objective: Our objective was to compare 3 socioeconomic status (SES) indexes and evaluate associations with outcomes after anterior cervical discectomy and fusion (ACDF) or lumbar fusion.

Background data: Socioeconomic disparities affect patients' baseline health and clinical outcomes following spine surgery. It is still unclear whether community-level indexes are accurate surrogates for patients' socioeconomic status (SES) and whether they are predictive of postoperative outcomes.

Methods: Adult patients undergoing ACDF (N=1189) or lumbar fusion (N=1136) from 2014 to 2020 at an urban tertiary medical center were retrospectively identified. Patient characteristics, patient-reported outcomes (PROMs), and surgical outcomes (90-day readmissions, complications, and nonhome discharge) were collected from the electronic medical record. SES was extracted from 3 indexes (Area Deprivation Index, Social Vulnerability Index, and Distressed Communities Index). Patients were classified into SES quartiles for bivariate and multivariate regression analysis. We utilized Youden's index to construct receiver operating characteristic curves for all surgical outcomes using indexes as continuous variables.

Results: Preoperatively, lumbar fusion patients in the poorest ADI community exhibited the greatest ODI (P=0.001) and in the poorest DCI and SVI communities exhibited worse VAS back (P<0.001 and 0.002, respectively). Preoperatively, ACDF patients in the lowest DCI community had significantly worse MCS-12, VAS neck, and NDI, and in the poorest ADI community had worse MCS-12 and NDI. There were no differences in the magnitude of improvement for any PROM. All indexes performed poorly at predicting surgical outcomes (AUC: 0.467-0.636, all P>0.05).

Conclusions: Community-wide SES indexes are not accurate proxies for individual SES. While patients from poorer communities present with worse symptoms, community-level SES is not associated with overall outcomes following spine fusion. Patient-specific factors should be employed when attempting to stratify patients based on SES given the inherent limitations present with these indexes.

Level of evidence: Level III.