Comparing the clinical outcomes of lumbar transforaminal vs interlaminar epidural steroid injections in a registry cohort

Background Transforaminal and interlaminar approaches are both common means of performing epidural steroid injection. Comparative effectiveness data on outcomes of these approaches is available but has yielded mixed results. Objective Compare the effect of transforaminal vs interlaminar delivery of epidural steroids on patient-reported pain severity. Design Retrospective Cohort Study. Methods A retrospective review of prospectively collected interventional spine procedure registry data between December 2011 and July 2017 from a single academic medical center. Those who received epidural steroid injections and had prospectively collected index pain data (11-point Numeric Rating Scale [NRS]) recorded in the patient's chart prior to the procedure and at a 3 month follow up appointment were included. The outcome of interest was ≥50% reduction in pain as measured using a NRS for back and/or leg pain. To evaluate true predictive odds of success, multivariable logistic regression modeling was used to determine the odds of achieving improved pain. Results Of the 73 patients included in the study, 61 (84%) reported radicular pain, 49 (67%) reported back pain, and eleven (15%) had symptoms consistent with claudication, pain characteristics were not mutually exclusive. Fifty-one (70%) underwent transforaminal epidural steroid injection, while 22 (30%) underwent interlaminar injection. When claudication and radicular pain groups were combined into a single “leg pain” category (n = 66), 26/46 (57% 95% CI 41–71%) patients undergoing transforaminal and 6/20 (30% 95% CI 12–54%) patients undergoing interlaminar injections achieved ≥50% leg pain reduction on NRS (p = 0.048). Transforaminal epidural steroid injections were associated with higher odds of ≥50% reduction in leg pain in both the unadjusted model (OR 3.2, p = 00.034) and after adjustment for presence of radicular pain on presentation and the type of steroid used (OR 3.6, p = 0.042). Conclusion In this clinical practice registry, patients treated with transforaminal epidural steroid injection were more likely to achieve ≥50% reduction in radicular or neurogenic/claudicatory leg pain compared to those treated with interlaminar epidural steroid injection.