Primary Care Access as a Predictor of Poor Outcomes Following Lumbar Spinal Fusion: A Novel Mechanism of Disparity

Introduction: Lumbar fusion is a common intervention for treatment of certain spinal pathologies. Disparities in lumbar fusion outcomes based on socioeconomic status have been demonstrated in literature, but the underlying mechanisms remain unclear. We hypothesize that healthcare access may be significantly associated with poor spine surgery outcomes. We sought to assess the association of low access to primary health care services and readmissions, reoperations, and complications following spinal fusion.

Methods: We retrospectively reviewed all adult patients at a single institution from 2011 to 2023 who underwent open and minimally invasive lumbar spine fusion using CPT and ICD9/10 codes. Patient addresses underwent geospatial analysis to retrieve census tract codes. Medically underserved Area(MUA) designations for census tracts were made according to the Health Resources Services Administration(HRSA). MUA designation is calculated based on access to primary care services in a designated census tract. Propensity score matching and multivariate analyses were performed to assess the effect of residence in a MUA and other variables on outcomes.

Results: We identified 2070 patients who met the inclusion criteria. The median age at time of operation was 64(IQR 56-71) and 362(9.5%) resided in a MUA. The overall 30-day readmission rate was 2.6%, with 41% of those patients having infection requiring reoperation. In multivariate regression adjusting for clinical and other socioeconomic variables, low access to care was associated with increased odds of 30-day (OR 3.29, 95% CI 1.59–6.40,p < 0.001) and 90-day readmissions(OR 2.41, 95%CI 1.35–4.11,p=0.002). Low access to care was also associated with increased odds of readmission due to infection within one year of index surgery (OR 2.81, 95%CI 1.22–5.91,p=0.009). After propensity-score matching by age, race, and comorbidity burden, patients with low access to care had increased rates of reoperation within 30 days (3.6% vs 1.0%, p=0.048), 90-day readmission (9.1% vs 4.3%,p=0.019), one-year readmission (14% vs 7.9%, p=0.015), and pseudoarthrosis (19% vs 13%,p=0.034) following index operation.

Conclusion : Our results strongly suggest that access to post-operative care may be an underlying driver of disparities in lumbar fusion surgery complications. Residence in a low access to care tract may be a novel risk factor useful for preoperative optimization and potential intervention to minimize complications.