A Multicountry Comparison of Three Coverage Evaluation Survey Sampling Methodologies for Neglected Tropical Diseases.

Coverage evaluation surveys (CESs) are an important complement to routinely reported drug coverage estimates following mass drug administration for neglected tropical diseases (NTDs). Although the WHO recommends the routine use of CESs, they are rarely implemented. Reasons for this low uptake are multifaceted; one is uncertainty on the best sampling method. We conducted a multicountry study to compare the statistical characteristics, cost, time, and complexity of three commonly used CES sampling methods: the Expanded Program on Immunization's (EPI's) 30 × 7 cluster survey, a stratified design with systematic sampling within strata to enable lot quality assurance sampling (S-LQAS) decision rules, and probability sampling with segmentation (PSS). The three CES methods were used in Burkina Faso, Honduras, Malawi, and Uganda, and results were compared across the country sites. All three CES methods were found to be feasible. The S-LQAS approach took the least amount of time to complete and, consequently, was the least expensive; however, all three methods cost less than $5,000 per district. The PSS design resulted in an unbiased, equal-probability sample of the target populations. By contrast, the EPI approach had inherent bias related to the selection of households. Because of modifications needed to maintain feasibility, the S-LQAS method also resulted in a non-probability sample with less precision than the other two methods. Given the comparable cost and time of the three sampling methods and the statistical advantages of the PSS method, the PSS method was deemed to be the best for CESs in NTD programs.

Ruling out early trimester pregnancy when implementing community-based deworming programs.

BACKGROUND: Large-scale deworming programs have, to date, mostly targeted preschool- and school-age children. As community-based deworming programs become more common, deworming will be offered to women of reproductive age. The World Health Organization recommends preventive chemotherapy be administered to pregnant women only after the first trimester. It is therefore important for deworming programs to be able to identify women in early pregnancy. Our objective was to validate a short questionnaire which could be used by deworming program managers to identify and screen out women in early pregnancy. METHODOLOGY/PRINCIPAL FINDINGS: In May and June 2018, interviewers administered a questionnaire, followed by a pregnancy test, to 1,203 adult women living in the Peruvian Amazon. Regression analyses were performed to identify questions with high predictive properties (using the pregnancy test as the gold standard). Test parameters were computed at different decision tree nodes (where nodes represented questions). With 106 women confirmed to be pregnant, the positive predictive value of asking the single question 'Are you pregnant?' was 100%, at a 'cost' of a false negative rate of 1.9% (i.e. 21 women were incorrectly identified as not pregnant when they were truly pregnant). Additional questions reduced the false negative rate, but increased the false positive rate. Rates were dependent on both the combination and the order of questions. CONCLUSIONS/SIGNIFICANCE: To identify women in early pregnancy when deworming programs are community-based, both the number and order of questions are important. The local context and cultural acceptability of different questions should inform this decision. When numbers are manageable and resources are available, pregnancy tests can be considered at different decision tree nodes to confirm pregnancy status. Trade-offs in terms of efficiency and misclassification rates will need to be considered to optimize deworming coverage in women of reproductive age.