Two-stage lot quality assurance sampling framework for monitoring and evaluation of neglected tropical diseases, allowing for imperfect diagnostics and spatial heterogeneity
Fig 9
The relative total survey cost of Kato-Katz thick smear with improved specificity.
The contour lines illustrate the total survey cost when applying a Kato-Katz thick smear with improved specificity KKsp(sekksp = 55%, and spkksp = 99%) with varying sample throughput and reagent cost to test one sample relative to the total cost of a survey based on the soil-transmitted helminths target product profiles diagnostic performance Dtpp1 (setpp1 = 60% and sptpp1 = 99%) with sample throughput (7 samples per hour per person) and cost characteristics (3 US$ reagent test cost). The dotted line indicates the maximum reagent cost per test for the improved Kato-Katz thick smear (1.85 US$) when the sample throughput was set at 7. The intra-cluster correlation ρi was set at 0.02 and the number of clusters at 10. The number of subjects per cluster was estimated as the required minimum number of subjects for adequate decision-making (Eovertreat = 25% and Eundertreat = 5%) around a program prevalence threshold of 2%, with the grey zone defined as T±50% (LL = 1%and UL = 3%). The total survey cost was defined as the minimal cost required. The graph was based on 10,000 Monte Carlo simulations.