Systematic review and meta-analysis of pharmacological therapies for pain associated with post-herpetic neuralgia

A systematic review and meta-analysis was conducted to estimate of the relative efficacy of pharmacologic therapies for the treatment of post-herpetic neuralgia (PHN). The published literature was searched through June 2011 for randomized, blinded, controlled clinical trials of pharmacologic treatments for PHN reporting predefined efficacy and safety outcomes. Bayesian mixed-treatment comparison (MTC) methods were used to determine the relative efficacy and harms for all therapies. Data from 29 studies including 26 interventions across 4,375 patients were identified and included in the MTC. Most treatments were effective vs. placebo in reducing PHN pain however several treatments were studied in very few patients, contributing greater uncertainty to model estimates. Among guideline-recommended treatments studied in &ge50 patients, aggregated results of opioids (morphine and methodone) reported in one study was most effective on the numeric pain rating scale (0-none to 10-worst), (mean reduction = -1.70, 95% credible interval [CrI] = -2.22, -1.80). On the visual analog scale (0-none to 100-worst), only tramadol (-9.40, CrI: -11.54, -7.26) and gabapentin (-6.46, CrI: -7.25, -5.65) were more effective than placebo. Pregabalin &ge300mg/day was the most effective treatment in reducing pain by 50% and 30% (relative risk [RR] vs. placebo = 2.44 and 2.13, respectively). Mixed evidence was seen with discontinuation rates of tricyclic antidepressants vs. placebo. A study reporting aggregate results of nortriptyline and desipramine demonstrated more discontinuations than placebo (4.07, CrI: 1.37, 6.41); however, estimates of nortriptyline (0.66, CrI: 0.06, 2.17) obtained from other studies did not show statistically different discontinuations. All treatments had more adverse events than placebo except lidocaine 5% plaster (0.93, CrI: 0.52, 1.32), tramadol (0.95, CrI: 0.63, 1.27), and amitryptyline (1.38 CrI: 0.89, 1.69). These indirect comparisons of PHN treatments can help decision makers better understand the relative benefit of a given choice of therapy. This research was supported by Pfizer, Inc.