Cost and cost-effectiveness of attractive targeted sugar baits (ATSB) in the context of a phase III cluster randomized control trial in Western Province, Zambia.

backgroundVector control is the most important malaria prevention strategy in Zambia. Attractive Targeted Sugar Baits (ATSB) are a potential new tool for vector control in this setting, which, if efficacious, would be intended to supplement insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS). ATSBs target and kill sugar feeding mosquitoes, potentially limiting the spread of malaria. No information on the cost or cost-effectiveness of deployment of ATSB stations is currently available.

methodsA cluster randomized control trial (cRCT) was carried out in Western Province, Zambia to assess the efficacy of Sarabi v.1.2 ATSB stations in a highly malarious setting. Costs associated with the procurement, distribution, maintenance, and disposal of the ATSB stations were collected over a two-year period. These costs were assessed alongside the main trial efficacy outcomes to determine cost-effectiveness and potential budget impact on the deployment of ATSB stations in this setting. Total costs, incremental costs, incremental cost-effectiveness ratios (ICER) and budget impact were estimated using trial data. One-way, scenario and probabilistic sensitivity analysis were performed to further determine the impact of assumptions and uncertainty on cost-effectiveness estimates, and the potential cost implications of alternative deployment scenarios. Sub-group analysis was performed to determine the impact of deployment in settings with the most favorable effect scenarios.

resultsThe total cost of the intervention in the context of the cRCT was USD 1,261,515. ATSB cost accounted for 46% of the total cost followed by personnel (25%), supplies and transport (13% each), equipment (2%) and storage (1%). Over the two year (14-month intervention) this resulted in an estimated ICER of USD 79 per malaria incident case averted or USD 919 per disability-adjusted life year (DALY) averted and USD 10.08 per person-year protected. In a subset of high-density ATSB clusters ICER was USD 42 per incident case averted and USD 493 per DALY averted and USD 4.35 per person-year protected. Probabilistic sensitivity analysis indicated that deployment in areas with higher structure density may be more cost-effective, especially if potential cost-savings are considered. However, effect estimates in this subgroup were highly uncertain and not statistically significant. While the scenario appeared more cost-effective than the base case on the cost-effectiveness acceptability curve (CEAC), the probability of cost-effectiveness reached only around 70%, falling short of the commonly used 80% threshold and remaining relatively weak.

conclusionsATSB Sarabi v.1.2 as deployed in western Zambia were not likely to be cost -effective. ATSB would need to demonstrate higher or more certain efficacy along with affordable alternative distribution strategies prior to any deployment at scale. Trial registration The trial is registered on clinicaltrials.gov under registration number: NCT04800055.