Cost-utility of tafenoquine vs. primaquine for the radical cure (prevention of relapse) of Plasmodium vivax malaria

Cost-Benefit Analysis of Tafenoquine for Radical Cure of Plasmodium vivax Malaria in Korea

BACKGROUND

Plasmodium vivax malaria has a persistent liver stage that causes relapse, and introducing tafenoquine to suppress relapse could aid in disease eradication. Therefore, we assessed the impact of tafenoquine introduction on P. vivax malaria incidence and performed a cost-benefit analysis from the payer's perspective.

METHODS

We expanded the previously developed P. vivax malaria dynamic transmission model and calibrated it to weekly civilian malaria incidences in 2014-2018. Primaquine and tafenoquine scenarios were considered by assuming different relapse probabilities, and relapse and total P. vivax malaria cases were predicted over the next decade for each scenario. We then estimated the number of cases prevented by replacing primaquine with tafenoquine. The cost and benefit of introducing tafenoquine were obtained using medical expenditure from a nationwide database, and a cost-benefit analysis was conducted. A probabilistic sensitivity analysis was performed to assess the economic feasibility robustness of tafenoquine introduction under uncertainties of model parameters, costs, and benefits.

RESULTS

Under 0.04 primaquine relapse probability, the introduction of tafenoquine with relapse probability of 0.01 prevented 129 (12.27%) and 35 (77.78%) total and relapse cases, respectively, over the next decade. However, under the same relapse probability as primaquine, introducing tafenoquine had no additional preventative effect. The 14-day primaquine treatment cost was $3.71. The tafenoquine and the glucose-6-phosphate dehydrogenase rapid diagnostic testing cost $57.37 and $7.76, totaling $65.13. The average medical expenditure per malaria patient was estimated at $1444.79. The cost-benefit analysis results provided an incremental benefit-cost ratio (IBCR) from 0 to 3.21 as the tafenoquine relapse probability decreased from 0.04 to 0.01. The probabilistic sensitivity analysis showed an IBCR > 1, indicating that tafenoquine is beneficial, with a probability of 69.1%.

CONCLUSION

Tafenoquine could reduce P. vivax malaria incidence and medical costs and bring greater benefits than primaquine.

Modelling in economic evaluations of medicines

Economic evaluation in health (also known as pharmacoeconomic in case of medicines) identifies, measures, and values costs and outcomes of alternative healthcare technologies, and can be performed alongside controlled clinical trials, but analytical modelling is usually used. Decision trees and Markov models are the two most common approaches used in economic evaluation. The biggest advantages of a decision tree are clarity, simplicity, and straightforwardness. On the other hand, the main advantage of the Markov model is its ability to incorporate complex events into the simulation, which is practically impossible to do with a decision tree. Reimbursement policy in Serbia mandatorily incorporates economic evaluations to promote availability and accessibility of the prescription medicines. To show current pharmacoeconomic value of a medicine, budget impact analysis and the cost-effectiveness analysis should be included. The latter should be conducted using appropriate modelling techniques. However, since no official methodological guidelines about the modelling and economic analysis exist, the submissions by marketing authorization holders vary greatly. The future of pharmacoeconomic modelling depends on the research area of interest, with new frameworks and approaches being developed.