Article type
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Abstract
Background: Lyme disease (LD) is the most frequently reported tick-borne disease in the U.S., with an overall incidence of 6.2 cases per 100,000, costing approximately 2.5 billion dollars for the prevention of 55,626 cases of LD sequelae over a five-year period. The value of the FDA approved vaccine for LD is controversial given the high curability of LD and low incidence rate in most geographic areas. Our aim was to determine if the LD vaccine is cost-effective and assess the parameters that influence its cost-effectiveness.
Methods: We constructed a Markov decision model to compare a vaccine strategy to a no vaccine strategy (DATA 3.0 software by TreeAge). We modeled presentation with LD in either early (erythema migrans +/- flu-like symptoms, 76% of cases) or late stages (24% of cases). Treatment options were oral antibiotics initially, except for severe late stage manifestations, which were treated with intravenous (IV) antibiotics. Failure of oral antibiotic treatment (5% of cases,30% of arthritis cases) resulted in treatment with IV antibiotics. Probabilities and direct medical costs of treatment and sequelae were obtained from published studies. Vaccine efficacy was incorporated in a time-dependent manner with efficacy of 49% in the first-year and 76% thereafter. Yearly and three-year booster regimens were analyzed.. The risk and costs of antibiotic reactions were also included in the analysis. Effectiveness was measured in cases of LD averted and overall direct costs of each strategy.
Results: In our preliminary analysis, results were sensitive to the annual incidence of LD, the number of years over which the analysis was run, and the level of protection in future years after immunization. Using the national incidence of the risk of developing LD, the vaccine strategy was more costly and only marginally more effective, with an incremental cost-effectiveness (C/E) ratio of $250,000 per case averted. However, at an annual incidence of 1%, the incremental C/E ratio was $1500 after ten years. The vaccine strategy with yearly boosters dominated at an annual incidence of approximately 5%.
Conclusion: Since the reported rate of LD approaches 1% in some geographic areas, the vaccine may be cost-effective only in selected, high risk populations. Given the societal anxiety surrounding this illness, our results may clarify an important source of confusion.
Methods: We constructed a Markov decision model to compare a vaccine strategy to a no vaccine strategy (DATA 3.0 software by TreeAge). We modeled presentation with LD in either early (erythema migrans +/- flu-like symptoms, 76% of cases) or late stages (24% of cases). Treatment options were oral antibiotics initially, except for severe late stage manifestations, which were treated with intravenous (IV) antibiotics. Failure of oral antibiotic treatment (5% of cases,30% of arthritis cases) resulted in treatment with IV antibiotics. Probabilities and direct medical costs of treatment and sequelae were obtained from published studies. Vaccine efficacy was incorporated in a time-dependent manner with efficacy of 49% in the first-year and 76% thereafter. Yearly and three-year booster regimens were analyzed.. The risk and costs of antibiotic reactions were also included in the analysis. Effectiveness was measured in cases of LD averted and overall direct costs of each strategy.
Results: In our preliminary analysis, results were sensitive to the annual incidence of LD, the number of years over which the analysis was run, and the level of protection in future years after immunization. Using the national incidence of the risk of developing LD, the vaccine strategy was more costly and only marginally more effective, with an incremental cost-effectiveness (C/E) ratio of $250,000 per case averted. However, at an annual incidence of 1%, the incremental C/E ratio was $1500 after ten years. The vaccine strategy with yearly boosters dominated at an annual incidence of approximately 5%.
Conclusion: Since the reported rate of LD approaches 1% in some geographic areas, the vaccine may be cost-effective only in selected, high risk populations. Given the societal anxiety surrounding this illness, our results may clarify an important source of confusion.