Definitions of the ratings of recommendations (A, B, C, U), translation of evidence to recommendations (A-C), and rating of therapeutic articles (Class I-IV) are provided at the end of the "Major Recommendations" field.
Recommendations
- Tricyclic antidepressants (amitriptyline, nortriptyline, desipramine, and maprotiline), gabapentin, pregabalin, opioids, and topical lidocaine patches are effective and should be used in the treatment of postherpetic neuralgia (Level A, class I and II). There is limited evidence to support nortriptyline over amitriptyline (Level B, single class II study) and the data are insufficient to recommend one opioid over another. Amitriptyline has significant cardiac effects in the elderly when compared to nortriptyline and desipramine.
- Aspirin in cream is possibly effective in the relief of pain in patients with postherpetic neuralgia (Level C, class II and III) but the magnitude of benefit is low, as is seen with capsaicin (Level A, class I and II).
- In countries where preservative-free intrathecal methylprednisolone is available, it may be considered in the treatment of postherpetic neuralgia (Level A, class I and II).
- Acupuncture, benzydamine cream, dextromethorphan, indomethacin, epidural methylprednisolone, epidural morphine sulfate, iontophoresis of vincristine, lorazepam, vitamin E, and zimelidine are not of benefit (Level B, class II).
- The effectiveness of carbamazepine, nicardipine, biperiden, chlorprothixene, ketamine, Helium:Neon (He:Ne) laser irradiation, intralesional triamcinolone, cryocautery, topical piroxicam, extract of Ganoderma lucidum, dorsal root entry zone lesions, and stellate ganglion block are unproven in the treatment of postherpetic neuralgia (Level U, single class II study and class IV studies).
- There is insufficient evidence at this time to make any recommendations on the long-term effects of these treatments.
Definitions:
Rating of Recommendation
A = Established as effective, ineffective, or harmful for the given condition in the specified population
B = Probably effective, ineffective, or harmful for the given condition in the specified population
C = Possibly effective, ineffective, or harmful for the given condition in the specified population
U = Data inadequate or conflicting. Given current knowledge, treatment is unproven
Translation of Evidence to Recommendations
Level A rating requires at least one convincing Class I study or at least two consistent, convincing Class II studies.
Level B rating requires at least one convincing Class II study or at least three consistent class III studies.
Level C rating requires at least two convincing and consistent Class III studies.
Rating of Therapeutic Article
Class I: Prospective, randomized, controlled clinical trial with masked outcome assessment, in a representative population. The following are required:
- Primary outcome(s) is/are clearly defined.
- Exclusion/inclusion criteria are clearly defined.
- Adequate accounting for dropouts and crossovers with numbers sufficiently low to have minimal potential for bias.
- Relevant baseline characteristics are presented and substantially equivalent among treatment groups, or there is appropriate statistical adjustment for differences.
Class II: Prospective matched group cohort study in a representative population with masked outcome assessment that meets a-d above OR a randomized, controlled trial in a representative population that lacks one criterion a-d
Class III: All other controlled trials (including well-defined natural history controls or patients serving as own controls) in a representative population, where outcome assessment is independent of patient treatment
Class IV: Evidence from uncontrolled studies, case series, case reports, or expert opinion