Evaluating the Effectiveness of Epidural Steroid Injections in Relieving Pain in a Single-Center Retrospective Cohort

Background Epidural steroid injections (ESIs) are a common conservative treatment for mitigating radicular pain and are often used to relieve pain, increase function, and improve mobility. However, their efficacy and duration of pain relief are relatively unclear because of the variability in clinical indications, injection techniques, injection mixtures, the number of allowable injections, and the lack of standard and objective outcome measures in the literature. Objectives This study aimed to characterize the effectiveness of ESIs in improving pain, measured with numerical rating scale (NRS) scores, and their relationship with subsequent lumbar spine surgery within a one-year period. Methods Patients who received a lumbar ESI from January 2018 to March 2022 in the Keck Medical Center of the University of Southern California were identified. Only patients with a one-year follow-up and no traumatic injuries were included. Exclusion criteria included a prior lumbar ESI within five years prior to January 2018. Demographics, comorbidities, injection information, and NRS scores were extracted. NRS score comparisons were analyzed with the Wilcoxon signed-rank test. Significance was defined at p ≤ 0.05. Results A total of 143 ESI patients were identified. The patient population consisted of 62 (43.36%) male, 81 (56.64%) female, and a median age of 63 years (IQR: 51,73). Patients who were one- and five-months post-ESI had the greatest median change in NRS of -3 (IQR: -7,0) (p < 0.05 for all). At one year post-ESI, there was a median decrease in NRS scores by 2 (IQR: 0,5). Of the cohort, only 28 (27.20%) patients went on to have lumbar spine surgery within a year. Conclusion The data suggests ESIs may be effective at relieving pain for at least one year. The data provides some evidence that ESIs are most reliable at relieving pain up to the five-month mark, after which their efficacy decreases.