Cost-effectiveness of intermittent preventive treatment of malaria in pregnancy in southern Mozambique

Abstract

Background: Malaria in pregnancy is a public health problem for endemic countries. Economic evaluations of malaria preventive strategies in pregnancy are needed to guide health policies.

Methods and findings: This analysis was carried out in the context of a trial of malaria intermittent preventive treatment in pregnancy with sulphadoxine-pyrimethamine (IPTp-SP), where both intervention groups received an insecticide treated net through the antenatal clinic (ANC) in Mozambique. The cost-effectiveness of IPTp-SP on maternal clinical malaria and neonatal survival was estimated. Correlation and threshold analyses were undertaken to assess the main factors affecting the economic outcomes and the cut-off values beyond which the intervention is no longer cost-effective. In 2007 US$, the incremental cost-effectiveness ratio (ICER) for maternal malaria was 41.46 US$ (95% CI 20.5, 96.7) per disability-adjusted life-year (DALY) averted. The ICER per DALY averted due to the reduction in neonatal mortality was 1.08 US$ (95% CI 0.43, 3.48). The ICER including both the effect on the mother and on the newborn was 1.02 US$ (95% CI 0.42, 3.21) per DALY averted. Efficacy was the main factor affecting the economic evaluation of IPTp-SP. The intervention remained cost-effective with an increase in drug cost per dose up to 11 times in the case of maternal malaria and 183 times in the case of neonatal mortality.

Conclusions: IPTp-SP was highly cost-effective for both prevention of maternal malaria and reduction of neonatal mortality in Mozambique. These findings are likely to hold for other settings where IPTp-SP is implemented through ANC visits. The intervention remained cost-effective even with a significant increase in drug and other intervention costs. Improvements in the protective efficacy of the intervention would increase its cost-effectiveness. Provision of IPTp with a more effective, although more expensive drug than SP may still remain a cost-effective public health measure to prevent malaria in pregnancy.

Trial registration: ClinicalTrials.gov NCT00209781.

Figure 1. Maternal malaria: acceptability curve of the cost-effectiveness ratio of IPTp-SP^a vs hypothetical willingness to pay^b.

^a Intermittent preventive treatment of malaria in pregnancy with sulphadoxine-pyrimethamine. ^b Acceptability curves were constructed by plotting the cumulative distribution of ICER of IPTp-SP per DALYs averted. The Y axis can be interpreted as probability that the intervention is cost-effective for every level of policy makers' ability or willingness to pay for each DALY averted (X axis). * 36 US$ per DALY averted = threshold of highly cost-effective intervention; 129 US$ per DALY averted = threshold of cost-effective intervention.

Figure 2. Correlation of cost-effectiveness ratios, savings, and input variables (Spearman's Rank).

^a Intermittent preventive treatment of malaria in pregnancy with sulphadoxine-pyrimethamine. ^bAntenatal Clinic (ANC) attendance at least twice during pregnancy. ^c Rate per person-year at risk in the placebo group. ^d Drug costs for inpatients refers to intravenous quinine. ^e Drug costs for outpatients are relative to artesunate plus SP. ^f It indicates the proportion of pregnant women with symptoms of malaria who seek formal health care.

Figure 3. Threshold analysis of the cost-effectiveness of IPTp-SP^a.

^a Intermittent preventive treatment of malaria in pregnancy with sulphadoxine-pyrimethamine ^b 129 US$/DALY averted. ^c 36 US$/DALY averted. Within the simulation ranges of each variable: * a threshold of 92.92 US$ was reached only. † a threshold of 96.79 US$ was reached only. ‡ a threshold of 85.99 US$ was reached only. ^ξ a threshold of 97.25 US$ was reached only.

Figure 4. Neonatal mortality: acceptability curve of the cost-effectiveness ratio of IPTp-SP^a vs hypothetical willingness to pay^b.

^a Intermittent preventive treatment of malaria in pregnancy with sulphadoxine-pyrimethamine. ^b Acceptability curves were constructed by plotting the cumulative distribution of ICER of IPTp-SP per DALYs averted. The Y axis can be interpreted as probability that the intervention is cost-effective for every level of policy makers' ability or willingness to pay for each DALY averted (X axis).