Cost-Effectiveness Analysis of Sex-Stratified Plasmodium vivax Treatment Strategies Using Available G6PD Diagnostics to Accelerate Access to Radical Cure.

David J Price,Ric N Price,Angela Devine,Benedikt Ley,Sabine Dittrich,Rosalind E Howes,Kerryn A Moore,Julie A Simpson

doi:10.4269/ajtmh.19-0943

Abstract

.Tafenoquine has been licensed for the single-dose radical cure of Plasmodium vivax in adults; however, it is only recommended in patients with > 70% of normal glucose-6-phosphate dehydrogenase (G6PD) activity. Because this may hinder widespread use, we investigated sex-based treatment strategies in which all adult patients are tested with a qualitative G6PD rapid diagnostic test (RDT). Glucose-6-phosphate dehydrogenase normal males are prescribed tafenoquine in all three strategies, whereas G6PD normal females are prescribed either a low-dose 14-day primaquine regimen (PQ14, total dose 3.5 mg/kg) or a high-dose 7-day primaquine regimen (PQ7, total dose 7 mg/kg), or referred to a healthcare facility for quantitative G6PD testing before prescribing tafenoquine. Patients testing G6PD deficient are prescribed a weekly course of primaquine for 8 weeks. We compared the cost-effectiveness of these three strategies to usual care in four countries using a decision tree model. Usual care in Ethiopia does not include radical cure, whereas Afghanistan, Indonesia, and Vietnam prescribe PQ14 without G6PD screening. The cost per disability-adjusted life-year (DALY) averted was expressed through incremental cost-effectiveness ratios (ICERs). Compared with usual care, the ICERs for a sex-based treatment strategy with PQ7 for females from a healthcare provider perspective were $127 per DALY averted in Vietnam, $466 in Ethiopia, $1,089 in Afghanistan, and $4,443 in Indonesia. The PQ14 and referral options cost more while averting fewer DALYs than PQ7. This study provides an alternative cost-effective mode of rolling out tafenoquine in areas where initial testing with only a G6PD RDT is feasible.

Highlights

Outside sub-Saharan Africa, Plasmodium vivax is a common cause of human malaria, with an estimated 14.3 million cases in 2017.1 The only available drugs that kill the dormant liver stages of P. vivax are the 8-aminoquinoline compounds primaquine and tafenoquine
Tafenoquine has been licensed for the single-dose radical cure of Plasmodium vivax in adults; it is only recommended in patients with > 70% of normal glucose-6-phosphate dehydrogenase (G6PD) activity
The incremental cost-effectiveness ratios (ICERs) for the PQ7 option ranged from $127 in Vietnam to $4,443 in Indonesia when compared with usual care

Summary

Introduction

Outside sub-Saharan Africa, Plasmodium vivax is a common cause of human malaria, with an estimated 14.3 million cases in 2017.1 The only available drugs that kill the dormant liver stages (hypnozoites) of P. vivax are the 8-aminoquinoline compounds primaquine and tafenoquine. The current WHO treatment guidelines recommend that primaquine is administered as a 14-day regimen at a total dose of 3.5 mg/kg (PQ14); a higher dose (total dose 7 mg/kg) is recommended in areas with a high risk of recurrence.[2] The prolonged treatment course extends long after symptomatic recovery and in practice is associated with poor patient adherence and low effectiveness.[3,4] Clinical trials have explored ways of shortening the course of primaquine without compromising safety or efficacy. For the purpose of this study, PQ14 corresponds to the low-dose regimen and PQ7 to the high-dose regimen

Methods

Results

Conclusion