Efficacy of Pain Relief in Different Postherpetic Neuralgia Therapies: A Network Meta-Analysis

Background: Postherpetic neuralgia (PHN) is a nerve pain disease usually controlled by different therapies, i.e., topical therapies, antiepileptics, analgesics, antipsychotics, antidepressants, anti-dementia drugs, antivirals, amitriptyline, fluphenazine, and magnesium sulfate. It is believed that different therapies may lead to different levels of pain relief. Objectives: We proposed this study to compare the efficacy of PHN treatments. Study Design: We conducted a systematic review of the current literature. All relevant studies were retrieved from online databases. The standardized mean difference (SMD) was used for pain relief measurement in different PHN therapies. Setting: A conventional meta-analysis and a network meta-analysis (NMA) were carried out together with the surface under the cumulative ranking curve (SUCRA) for each therapy calculated regarding their efficacy. Results: A pairwise meta-analysis suggested that 4 treatment classes, including topical therapies, antiepileptics, analgesics, and antidepressants, exhibited better pain relief results than placebo. Likewise, a NMA suggested that patients with 4 treatment classes exhibited significant improvements in pain scores compared to those with placebo. Limitations: There is a lack of direct head-to-head comparisons of some treatments, especially for antivirals, anti-dementia drugs, and magnesium sulfate. Secondly, the specific agents belonging to the same class of therapies might exhibit different effects (gabapentin and carisbamate) with different mechanisms (opioids and ketamine) on reducing pain, and some agents were hard to find in literatures and were not involved in our study, which may influence our results. Conclusions: Analgesics were preferable to other treatments with respect to pain relief for PHN, while antivirals appeared to be less effective than other therapies. Key words: Postherpetic neuralgia, topical agents, antiepileptics, analgesics, antipsychotics, antidepressants