Impact of Racial and Socioeconomic Disparities on Access to Interspinous Spacer for Treatment of Lumbar Spinal Stenosis: A Nationwide Medicare Analysis

Abstract Background In mild to moderate lumbar spinal stenosis (LSS) where conservative care treatments fail, minimally invasive treatments, such as interspinous spacers without decompression or fusion (ISD), may be appropriate. While previous studies have demonstrated racial and socioeconomic disparities in the surgical treatment of LSS, there are limited data on how those factors impact accessibility to these procedures. This study explored demographic, socioeconomic, and geographic differences in the use of ISD. Methods Using the Medicare 100% files from 2017 through 2022, this retrospective claims analysis identified when and if patients diagnosed with LSS received ISD implantation. Cox proportional hazards regression was used to examine the association between racial and socioeconomic characteristics and the rate of ISD implantation, stratified by geographic region. Results A total of 1,316,622 individuals met the inclusion criteria; 4730 (0.4%) underwent ISD implantation, with a mean (standard deviation) time to treatment of 11.9 (13.2) months after diagnosis. The likelihood of ISD implantation was higher for older patients (except for the oldest group), males, those with lower disease burden, and White patients. Cox regression revealed that the associations of racial and socioeconomic factors with ISD implantation varied by U.S. region. In the Midwest and Northeast, lower median household income was associated with a decreased likelihood of ISD implantation regardless of race, while in the South, Black patients were less likely to undergo ISD implantation regardless of income. Conclusions The observed disparities in access to ISD implantation mirror existing trends in surgical interventions for LSS, suggesting further study and interventions are needed to address inequities.