Effect of Epidural Block in the Incidence of Postherpetic Neuralgia: A Population-Based Matched-Cohort Study

BACKGROUND: Incidence of postherpetic neuralgia (PHN) increases with age. Epidural block in patients with herpes zoster (HZ) is expected to decrease the risk of PHN. The purpose of this study was to evaluate the effectiveness of epidural block on PHN incidence in a population-based study. METHODS: This was a retrospective matched cohort study and data were sourced from the Korean National Health Insurance Service. The study cohort comprised 427 patients diagnosed with HZ who received epidural block within 30 days after a diagnosis of HZ. The matched control cohort included 427 patients without epidural block and were randomly matched to the study cohort at a 1:1 ratio based on covariates such as sociodemographic factors. The log-rank test was used to assess differences in the incidence of PHN. Cox proportional hazards regression models were used to estimate the hazard ratio (HR) for subsequent PHN, while controlling for potential comorbidities. RESULTS: Among the 854 sampled patients, 30 (7.03%) from the study cohort and 18 (4.22%) from the match-control developed PHN during follow-up. There were no significant differences in the incidence of PHN between the two cohorts (p=0.08). Cox proportional hazard regressions showed that the HR for PHN in patients with epidural block was 1.66 (95% confidence interval, 0.91–3.02; p=0.10). CONCLUSION: Our study indicates that epidural block did not effectively prevent PHN. However, further studies are needed to determine the effect of epidural block in patients with HZ for the prevention of PHN.