Cost effectiveness of a lidocaine 5% medicated plaster compared with pregabalin for the treatment of postherpetic neuralgia in the UK: a Markov model analysis.

backgroundPublished analyses have demonstrated that the lidocaine (lignocaine) plaster is a cost-effective treatment for postherpetic neuralgia (PHN) relative to gabapentin or pregabalin. However, these analyses have been based on indirect comparisons from placebo-controlled trials, and there is evidence of a discrepancy between the outcomes of direct and indirect analyses. Fortunately, recent publication of the results of a head-to-head trial comparing the lidocaine plaster and pregabalin in patients with PHN or diabetic polyneuropathy allows customization of the existing model to more accurately reflect the relative cost effectiveness of these two products.

objectiveTo assess the cost-effectiveness of the lidocaine 5% medicated plaster compared with pregabalin for the treatment of PHN in the UK primary-care setting.

methodsA Markov model has been developed to assess the costs and benefits of the lidocaine plaster and pregabalin over a 6-month time horizon for the treatment of patients with PHN who are intolerant to tricyclic antidepressants and in whom analgesics are ineffective or contraindicated. The model structure allows for differences in costs, utilities (derived from published data and from the head-to-head trial) and transition probabilities between the initial 30-day run-in period and maintenance therapy, and also takes account of add-in medication and drugs received by patients discontinuing therapy. The calculation was based on data from the recent head-to-head trial described above. Additional data sources included published literature, discussions with a Delphi panel, official price/tariff lists and national population statistics. The study was conducted from the perspective of the UK National Health Service (NHS).

resultsThe base-case analysis (1.71 lidocaine plasters per day used in the head-to-head trial for the PHN population) indicated that the total cost of treating PHN patients for 6 months with the lidocaine plaster was pound 980 per patient treated, compared with pound 784 for pregabalin (year of costing 2009). Costs for 1 month without pain and intolerable adverse events (AEs) (modified TWIST analysis) were pound 126 for the lidocaine plaster relative to pregabalin. The average patient treated with the lidocaine plaster experienced 0.321 quality-adjusted life-years (QALYs) over the 6-month period modelled compared with 0.254 QALYs for pregabalin. Quality-of-life benefits were attributed to the favourable AE profile of the lidocaine plaster. Subsequently, the lidocaine plaster cost pound 2925 per QALY gained relative to pregabalin. However, patient level longitudinal data have shown that the actual clinical usage of the lidocaine plaster is 1.1 plasters per day. If this more realistic assumption is used in the model, the total cost for a 6-month treatment period was pound 756 for the lidocaine plaster, which dominated treatment with pregabalin. Scenario analyses and sensitivity analyses had minimal impact on the results, confirming the robustness of the study. The incremental cost-effectiveness ratios for the lidocaine plaster remained well below pound 35,000 per QALY gained in all analyses.

conclusionThis analysis showed that the lidocaine 5% medicated plaster is a cost-effective method for obtaining sustained relief of localized neuropathic pain associated with PHN compared with pregabalin in a UK setting, in terms of both the cost per QALY gained and the cost per additional month without symptoms, when used for patients who do not experience sufficient pain relief from standard analgesics.