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Cost-Effectiveness of Antivenoms for Snakebite Envenoming in 16 Countries in West Africa.

Hamza M, Idris MA, Maiyaki MB, Lamorde M, Chippaux JP, Warrell DA, Kuznik A, Habib AG - PLoS Negl Trop Dis (2016)

Bottom Line: We determined the cost-effectiveness of AV based on a decision-tree model from a public payer perspective.Therapy for SBE with AV in countries of WA is highly cost-effective at commonly accepted thresholds.Broadening access to effective AVs in rural communities in West Africa is a priority.

View Article: PubMed Central - PubMed

Affiliation: College of Health of Sciences, Bayero University, Kano, Nigeria.

ABSTRACT

Background: Snakebite poisoning is a significant medical problem in agricultural societies in Sub Saharan Africa. Antivenom (AV) is the standard treatment, and we assessed the cost-effectiveness of making it available in 16 countries in West Africa.

Methods: We determined the cost-effectiveness of AV based on a decision-tree model from a public payer perspective. Specific AVs included in the model were Antivipmyn, FAV Afrique, EchiTab-G and EchiTab-Plus. We derived inputs from the literature which included: type of snakes causing bites (carpet viper (Echis species)/non-carpet viper), AV effectiveness against death, mortality without AV, probability of Early Adverse Reactions (EAR), likelihood of death from EAR, average age at envenomation in years, anticipated remaining life span and likelihood of amputation. Costs incurred by the victims include: costs of confirming and evaluating envenomation, AV acquisition, routine care, AV transportation logistics, hospital admission and related transportation costs, management of AV EAR compared to the alternative of free snakebite care with ineffective or no AV. Incremental Cost Effectiveness Ratios (ICERs) were assessed as the cost per death averted and the cost per Disability-Adjusted-Life-Years (DALY) averted. Probabilistic Sensitivity Analyses (PSA) using Monte Carlo simulations were used to obtain 95% Confidence Intervals of ICERs.

Results: The cost/death averted for the 16 countries of interest ranged from $1,997 in Guinea Bissau to $6,205 for Liberia and Sierra Leone. The cost/DALY averted ranged from $83 (95% Confidence Interval: $36-$240) for Benin Republic to $281 ($159-457) for Sierra-Leone. In all cases, the base-case cost/DALY averted estimate fell below the commonly accepted threshold of one time per capita GDP, suggesting that AV is highly cost-effective for the treatment of snakebite in all 16 WA countries. The findings were consistent even with variations of inputs in 1-way sensitivity analyses. In addition, the PSA showed that in the majority of iterations ranging from 97.3% in Liberia to 100% in Cameroun, Guinea Bissau, Mali, Nigeria and Senegal, our model results yielded an ICER that fell below the threshold of one time per capita GDP, thus, indicating a high degree of confidence in our results.

Conclusions: Therapy for SBE with AV in countries of WA is highly cost-effective at commonly accepted thresholds. Broadening access to effective AVs in rural communities in West Africa is a priority.

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Related in: MedlinePlus

Tornado diagrams assessing the impact of changes in envenoming/antivenom and cost parameters on the incremental cost-effectiveness ratio (ICER) per DALY for antivenom use in Guinea Bissau (L) and Senegal (R).Diagram parameter definitions: c20WBCTest = cost of 20 minutes Whole Blood Clotting Test on 10 occassions over 7 days at diagnoses and monitoring; cAntivenom = Cost of Antivenom; cFeed_Transp = Cost of transporation and stay in Hospital for 7days; cRefrg_Transp = Cost of shipping and refrigeration; cNoAntivenom = Cost of management without effective antivenoms either traditional/herbal care or other alternatives; cSupp_care = Cost of supportive care. All costs are in US$. Antivenomeff = Effectiveness of antivenom to prevent death; pEARmono = probability of early adverse reactions with monospecific antivenom; pEARpoly = probability of early adverse reactionswith polyspecific antivenom; pEARmort = probability of dying following effective antivenom and early adverse reactions; pCVmort = probability of dying following carpet viper envenoming; pNCVmort = probability of dying following non-carpet viper envenoming; pCV = proportion of envenoming due to carpet viper; pDisabl = probability of disability.
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pntd.0004568.g002: Tornado diagrams assessing the impact of changes in envenoming/antivenom and cost parameters on the incremental cost-effectiveness ratio (ICER) per DALY for antivenom use in Guinea Bissau (L) and Senegal (R).Diagram parameter definitions: c20WBCTest = cost of 20 minutes Whole Blood Clotting Test on 10 occassions over 7 days at diagnoses and monitoring; cAntivenom = Cost of Antivenom; cFeed_Transp = Cost of transporation and stay in Hospital for 7days; cRefrg_Transp = Cost of shipping and refrigeration; cNoAntivenom = Cost of management without effective antivenoms either traditional/herbal care or other alternatives; cSupp_care = Cost of supportive care. All costs are in US$. Antivenomeff = Effectiveness of antivenom to prevent death; pEARmono = probability of early adverse reactions with monospecific antivenom; pEARpoly = probability of early adverse reactionswith polyspecific antivenom; pEARmort = probability of dying following effective antivenom and early adverse reactions; pCVmort = probability of dying following carpet viper envenoming; pNCVmort = probability of dying following non-carpet viper envenoming; pCV = proportion of envenoming due to carpet viper; pDisabl = probability of disability.

Mentions: The findings from the analyses were also consistent to variations of inputs in 1-way sensitivity and scenario analyses as depicted (Table 3 and Fig 2). The individual countries’ model results were most sensitive to effectiveness of antivenom in decreasing mortality, natural (unattended) mortality, costs of antivenoms and types of snake causing envenoming (Fig 2). Results were not sensitive to antivenom associated EAR or the cost of managing it. Varying the cost of antivenom from $125 to two times for victims who may require two doses, i.e. $306, still yielded ICER estimates that remain cost-effective. The ICERs rose when the frequency of snakebite envenomation due to saw-scaled viper was reduced to 0% except in Benin and Guinea Conakry where Antivipmyn antivenom is used and is effective even against elapids (Table 3) [42].


Cost-Effectiveness of Antivenoms for Snakebite Envenoming in 16 Countries in West Africa.

Hamza M, Idris MA, Maiyaki MB, Lamorde M, Chippaux JP, Warrell DA, Kuznik A, Habib AG - PLoS Negl Trop Dis (2016)

Tornado diagrams assessing the impact of changes in envenoming/antivenom and cost parameters on the incremental cost-effectiveness ratio (ICER) per DALY for antivenom use in Guinea Bissau (L) and Senegal (R).Diagram parameter definitions: c20WBCTest = cost of 20 minutes Whole Blood Clotting Test on 10 occassions over 7 days at diagnoses and monitoring; cAntivenom = Cost of Antivenom; cFeed_Transp = Cost of transporation and stay in Hospital for 7days; cRefrg_Transp = Cost of shipping and refrigeration; cNoAntivenom = Cost of management without effective antivenoms either traditional/herbal care or other alternatives; cSupp_care = Cost of supportive care. All costs are in US$. Antivenomeff = Effectiveness of antivenom to prevent death; pEARmono = probability of early adverse reactions with monospecific antivenom; pEARpoly = probability of early adverse reactionswith polyspecific antivenom; pEARmort = probability of dying following effective antivenom and early adverse reactions; pCVmort = probability of dying following carpet viper envenoming; pNCVmort = probability of dying following non-carpet viper envenoming; pCV = proportion of envenoming due to carpet viper; pDisabl = probability of disability.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814077&req=5

pntd.0004568.g002: Tornado diagrams assessing the impact of changes in envenoming/antivenom and cost parameters on the incremental cost-effectiveness ratio (ICER) per DALY for antivenom use in Guinea Bissau (L) and Senegal (R).Diagram parameter definitions: c20WBCTest = cost of 20 minutes Whole Blood Clotting Test on 10 occassions over 7 days at diagnoses and monitoring; cAntivenom = Cost of Antivenom; cFeed_Transp = Cost of transporation and stay in Hospital for 7days; cRefrg_Transp = Cost of shipping and refrigeration; cNoAntivenom = Cost of management without effective antivenoms either traditional/herbal care or other alternatives; cSupp_care = Cost of supportive care. All costs are in US$. Antivenomeff = Effectiveness of antivenom to prevent death; pEARmono = probability of early adverse reactions with monospecific antivenom; pEARpoly = probability of early adverse reactionswith polyspecific antivenom; pEARmort = probability of dying following effective antivenom and early adverse reactions; pCVmort = probability of dying following carpet viper envenoming; pNCVmort = probability of dying following non-carpet viper envenoming; pCV = proportion of envenoming due to carpet viper; pDisabl = probability of disability.
Mentions: The findings from the analyses were also consistent to variations of inputs in 1-way sensitivity and scenario analyses as depicted (Table 3 and Fig 2). The individual countries’ model results were most sensitive to effectiveness of antivenom in decreasing mortality, natural (unattended) mortality, costs of antivenoms and types of snake causing envenoming (Fig 2). Results were not sensitive to antivenom associated EAR or the cost of managing it. Varying the cost of antivenom from $125 to two times for victims who may require two doses, i.e. $306, still yielded ICER estimates that remain cost-effective. The ICERs rose when the frequency of snakebite envenomation due to saw-scaled viper was reduced to 0% except in Benin and Guinea Conakry where Antivipmyn antivenom is used and is effective even against elapids (Table 3) [42].

Bottom Line: We determined the cost-effectiveness of AV based on a decision-tree model from a public payer perspective.Therapy for SBE with AV in countries of WA is highly cost-effective at commonly accepted thresholds.Broadening access to effective AVs in rural communities in West Africa is a priority.

View Article: PubMed Central - PubMed

Affiliation: College of Health of Sciences, Bayero University, Kano, Nigeria.

ABSTRACT

Background: Snakebite poisoning is a significant medical problem in agricultural societies in Sub Saharan Africa. Antivenom (AV) is the standard treatment, and we assessed the cost-effectiveness of making it available in 16 countries in West Africa.

Methods: We determined the cost-effectiveness of AV based on a decision-tree model from a public payer perspective. Specific AVs included in the model were Antivipmyn, FAV Afrique, EchiTab-G and EchiTab-Plus. We derived inputs from the literature which included: type of snakes causing bites (carpet viper (Echis species)/non-carpet viper), AV effectiveness against death, mortality without AV, probability of Early Adverse Reactions (EAR), likelihood of death from EAR, average age at envenomation in years, anticipated remaining life span and likelihood of amputation. Costs incurred by the victims include: costs of confirming and evaluating envenomation, AV acquisition, routine care, AV transportation logistics, hospital admission and related transportation costs, management of AV EAR compared to the alternative of free snakebite care with ineffective or no AV. Incremental Cost Effectiveness Ratios (ICERs) were assessed as the cost per death averted and the cost per Disability-Adjusted-Life-Years (DALY) averted. Probabilistic Sensitivity Analyses (PSA) using Monte Carlo simulations were used to obtain 95% Confidence Intervals of ICERs.

Results: The cost/death averted for the 16 countries of interest ranged from $1,997 in Guinea Bissau to $6,205 for Liberia and Sierra Leone. The cost/DALY averted ranged from $83 (95% Confidence Interval: $36-$240) for Benin Republic to $281 ($159-457) for Sierra-Leone. In all cases, the base-case cost/DALY averted estimate fell below the commonly accepted threshold of one time per capita GDP, suggesting that AV is highly cost-effective for the treatment of snakebite in all 16 WA countries. The findings were consistent even with variations of inputs in 1-way sensitivity analyses. In addition, the PSA showed that in the majority of iterations ranging from 97.3% in Liberia to 100% in Cameroun, Guinea Bissau, Mali, Nigeria and Senegal, our model results yielded an ICER that fell below the threshold of one time per capita GDP, thus, indicating a high degree of confidence in our results.

Conclusions: Therapy for SBE with AV in countries of WA is highly cost-effective at commonly accepted thresholds. Broadening access to effective AVs in rural communities in West Africa is a priority.

Show MeSH
Related in: MedlinePlus