Zoster-associated pain: pretreatment time interval is inversely associated with pulsed radiofrequency effectiveness in a retrospective mono-institutional analysis.

Background: Pulsed radiofrequency (PRF) is an effective treatment for herpes zoster-associated pain (ZAP), the optimal time to perform the PRF treatment remains unclear. This study aimed to explore this relationship and determine the optimal timing for PRF intervention.

Methods: This research conduct a single-center retrospective cohort study in China. 303 patients who received PRF treatment for ZAP were followed up for 3 months. The primary endpoints were numerical rating scale (NRS) score and NRS reduction rate. Multiple assessment scales were used to evaluate pain and symptoms. Cox regression analysis and restricted cubic spline analysis were performed to examine the relationship between pre-treatment time interval (PTI) and outcomes.

Results: 69.9% achieved positive outcomes after PRF treatment. The incidence of positive outcomes decreased from 82.14% in the lowest PTI quartile to 48% in the highest. After adjusting for confounding factors, prolonged PTI was associated with an increased risk of negative PRF outcomes. Restricted Cube Spline (RCS) analysis revealed a non-linear relationship between PTI and treatment outcomes, with the risk of negative outcomes increasing rapidly initially before plateauing.

Conclusions: The optimal timing for PRF treatment was determined to be within 1.5 months of herpes onset. Single-center results may be influenced by institution-specific practices and physician-related biases, and longer follow-up period is necessary.