Predictors of response in patients with traumatic peripheral neuropathic pain treated with the 8% capsaicin patch.

Abstract

Background and objectives: Neuropathic pain (NP) is a widespread, complex disorder that responds differently to pharmacological treatment. The aim of this study was to identify the baseline characteristics of good response to capsaicin 8% patch in patients with trauma-induced peripheral neuropathic pain (PNP).

Materials and methods: We performed a prospective, longitudinal, open-label study in 31 patients with PNP treated with 1-3 applications of the capsaicin 8% patch for 52 weeks. Response to treatment was defined as a reduction in the Visual Analogue Scale (VAS) score compared to baseline. Data from responders and non-responders were compared at the start (month 1) and end (month 12) of treatment. Logistic regression was used to identify predictors of treatment response.

Results: At month 1, responders (n = 17) had significantly larger treatment areas (155.18 cm² vs. 59.21 cm²; p = 0.004) and reported greater pain relief with treatments received in the previous week in the brief pain questionnaire (34.7% vs. 14.3%; p = 0.023). At month 12, significant predictors included cold allodynia (OR 8; p = 0.030), positive for painful cold in the DN4 questionnaire (OR 7.936; p = 0.019), no penetrating pain (OR 16.800; p = 0.009), and pain interference with work score <7.5 (OR 7.917; p = 0.019).

Conclusions: This study makes a significant contribution to the management of post-traumatic peripheral neuropathic pain by providing tools to personalise treatment and optimize available resources.