The Influence of Hospital Type, Insurance Type, and Patient Income on 30-Day Complication and Readmission Rates Following Lumbar Spine Fusion
Authors: Chen Matthew , Ton Andy , Shahrestani Shane , Chen Xiao , Ballatori Alexander , Wang Jeffrey C , Buser Zorica 
Published: December 2023

Background Context Several studies have shown that factors such as insurance type and patient income are associated with different readmission rates following certain orthopaedic procedures. The literature, however, remains sparse with regard to these demographic characteristics and their associations to perioperative lumbar spine fusion outcomes. Purpose The purpose of this study was to assess the associations between hospital type, insurance type, and patient median income to both 30-day complication and readmission rates following lumbar spine fusion. Patient Sample Patients who underwent primary lumbar spine fusion (n = 596,568) from 2010-2016 were queried from the National Readmissions Database (NRD). Outcome Measures Incidence of 30-day complication and readmission rates Methods All relevant diagnoses and procedures were identified using International Classification of Disease, 9th and 10th Edition (ICD-9, 10) codes. Hospital types were categorized as metropolitan non-teaching (n = 212,131), metropolitan teaching (n = 364,752), and rural (n = 19,685). Insurance types included: Medicare (n = 213,534), Medicaid (n = 78,520), private insurance (n = 196,648), and out-of-pocket (n = 45,025). Patient income was divided into the following quartiles: Q1 (n = 112,083), Q2 (n = 145,755), Q3 (n = 156,276), and Q4 (n = 147,289), wherein quartile 1 corresponded to lower income ranges and quartile 4 to higher ranges. Statistical analysis was conducted in R. Kruskal-Wallis tests with Dunn’s pairwise comparisons were performed to analyze differences in 30-day readmission and complication rates in patients who underwent lumbar spine fusion. Complications analyzed included infection, wound injury, hematoma, neurological injury, thromboembolic event, and hardware failure. Results 30-day readmission was significantly higher in metropolitan teaching hospitals compared to metropolitan non-teaching hospitals and rural hospitals ( P < .05). Patients from metropolitan teaching hospitals had significantly higher rates of infection ( P < .001), wound injury ( P < .001), hematoma ( P = .018), and hardware failure ( P < .002) compared to those treated at metropolitan non-teaching hospitals. Privately insured patients were significantly less likely to be readmitted at 30 days than those paying with Medicare or Medicaid ( P < .01). Patients with private insurance also experienced significantly lower rates of hematoma formation than Medicare beneficiaries and out-of-pocket payers ( P < .01), postoperative wound injury compared to Medicaid patients and out-of-pocket payers ( P < .005), and infection compared to all other groups ( P < .001). Patients in Quartile 4 experienced significantly greater rates of hematoma formation compared to those in Quartiles 1 and 2 and were more likely to experience a thromboembolic event compared to all other groups. Conclusion Patients undergoing lumbar spine fusion at metropolitan non-teaching hospitals and paying with private insurance had significantly lower 30-day readmission rates than their counterparts. Complications within 30 days following lumbar spine fusion were significantly higher in patients treated at metropolitan teaching hospitals and in Medicare and Medicaid beneficiaries. Aside from a few exceptions, however, patient income was generally not associated with differential complication rates.