Efficacy and Predictive Factors of Systemically Acting Diclofenac Sodium Patch for Chronic Low Back Pain: A Retrospective Observational Study

Abstract

Introduction: Chronic low back pain (CLBP) is a complex condition significantly impacting global health. While non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used for treatment, factors influencing their efficacy remain poorly understood. This study investigated the therapeutic effects of systemically acting diclofenac sodium patches in patients with CLBP and factors influencing their efficacy, focusing on psychiatric factors and neuropathic pain components in short-term (4 weeks) and long-term (12 weeks) outcomes.

Methods: This multicenter retrospective observational study included 196 patients with CLBP treated with diclofenac sodium patches (150 mg/day). The visual analog scale (VAS) evaluated the intensity of LBP. Psychiatric factors were assessed using the Brief Scale for Psychiatric Problems in Orthopedic Patients (BS-POP), and neuropathic pain was evaluated using the short form of the Spine painDETECT questionnaire (SF-SPDQ). Multiple regression analyses were performed to identify predictive factors.

Results: LBP VAS scores significantly improved from baseline (72.4±15.4) to 12 weeks (42.6±23.5). Among the participants, 112 (57.1%) had comorbid pain, defined as chronic musculoskeletal pain in sites other than low back and radiating leg pain. Multiple regression analysis revealed that psychiatric factors (BS-POP score; regression coefficient=−1.10, p=0.026) and presence of comorbid pain (regression coefficient=−9.50, p=0.021) were significant negative predictors at 4 weeks, with their impact increasing at 12 weeks (BS-POP score: regression coefficient=−2.51, p<0.001; comorbid pain: regression coefficient=−11.73, p=0.020). Neuropathic pain components negatively affected only short-term outcomes.

Conclusions: Psychiatric factors and comorbid pain significantly influence the efficacy of diclofenac sodium patches in CLBP treatment, with their impact increasing over time. These findings emphasize the importance of comprehensive patient assessment before initiating NSAID treatment and suggest the need for early multifaceted intervention in patients with psychiatric factors and comorbid pain.