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.