Pain Phenotypes and Hematological Inflammatory Indices as Predictors of Transforaminal Epidural Steroid Injection...

Background and Objectives: Predicting treatment response following transforaminal epidural steroid injection (TFESI) in older adults with lumbar radicular pain (LRP) remains challenging. Hematological inflammatory indices have been proposed as accessible biomarkers; however, their clinical utility remains uncertain. This study aimed to evaluate the predictive value of preprocedural hematological inflammatory indices and determine whether clinical variables provide a more clinically relevant framework for predicting TFESI outcomes. Materials and Methods: This retrospective observational study included 190 patients aged ≥65 years who underwent TFESI for LRP. Pain intensity was assessed using the Numeric Rating Scale (NRS) at baseline and after 3 months. Treatment response was defined as a ≥50% reduction in the NRS (meaningful pain response, [MPR-50]). Pre-procedural hematological parameters and derived indices, including the neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), systemic inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI), were calculated. The pain phenotype was categorized as nociceptive, neuropathic, or mixed using the Douleur Neuropathique 4 (DN4) scale. Univariate and multivariable logistic regression analyses were performed, and receiver operating characteristic (ROC) analysis was used to assess the discriminative performance. Results: A meaningful pain response was achieved in 61.1% of the patients. Lymphocyte and monocyte counts were higher in responders; however, effect sizes were small. Importantly, patients with neuropathic pain exhibited significantly higher monocyte counts, SIRI, and AISI, indicating an association between pain phenotype and systemic inflammatory burden; however, these markers were not associated with treatment response. Furthermore, isolated inflammatory indices demonstrated limited standalone discriminative performance in the ROC analysis. In the adjusted hematological model, NLR demonstrated a modest statistical association with MPR-50; however, this association weakened in the final integrated model. Conclusion: Inflammatory indices and pain phenotypes may reflect biological and clinical heterogeneity in older adults with LRP; however, their standalone predictive value for TFESI outcomes appears limited. TFESI responsiveness is likely multifactorial and may be better evaluated using an integrated clinical framework.