OBJECTIVE: To evaluate the impact of social determinants of health (race/ethnicity, household income, insurance) and hospital surgical volume on 30- and 90-day readmissions after lumbar spinal fusion surgery. METHODS: A retrospective review of the State Inpatient Databases (SID) Healthcare Cost and Utilization Project (HCUP) included all patients age ≥18 years who underwent an index lumbar spinal fusion procedure and met inclusion criteria in California (2007-2011), Maryland (2012-2014), Florida, and New York (2007-2014). Primary outcomes were unadjusted rates and adjusted odds of readmission at 30 and 90 days postoperatively. RESULTS: After assessing for exclusion criteria, 267,976 patients were included in analyses. The overall 30-day readmission rate was 7.5%, and the 90-day readmission rate was 11.6%. Black patients (odds ratio [OR] = 1.12, 95% confidence interval [CI] = 1.06-1.19) and patients with nonprivate insurance (Medicare OR = 1.44, 95% CI = 1.37-1.51; Medicaid OR = 1.46, 95% CI = 1.36-1.56; or uninsured OR = 1.16, 95% CI = 1.00-1.35) had higher odds of 30-day readmission, with comparable effects at 90 days. The three highest quartiles of hospital lumbar spine surgical volume had decreased odds for 30- and 90-day readmission when compared with the lowest quartile. Median income had no effect on readmission rates, save for the top quartile having lower odds of 90-day readmission than the bottom quartile. CONCLUSIONS: Sociodemographic disparities in primary insurance payer, race/ethnicity, and hospital surgical volume affect lumbar spinal fusion surgery readmission rates. Public health interventions may improve readmissions and clinical outcomes and reduce health care costs.
