Overestimation of school-based deworming coverage resulting from school-based reporting

Abstract

Background: Soil Transmitted Helminths (STH) infect over 1.5 billion people globally and are associated with anemia and stunting, resulting in an annual toll of 1.9 million Disability-Adjusted Life Years (DALYs). School-based deworming (SBD), via mass drug administration (MDA) campaigns with albendazole or mebendazole, has been recommended by the World Health Organization to reduce levels of morbidity due to STH in endemic areas. DeWorm3 is a cluster-randomized trial, conducted in three study sites in Benin, India, and Malawi, designed to assess the feasibility of interrupting STH transmission with community-wide MDA as a potential strategy to replace SBD. This analysis examines data from the DeWorm3 trial to quantify discrepancies between school-level reporting of SBD and gold standard individual-level survey reporting of SBD.

Methodology/principal findings: Population-weighted averages of school-level SBD calculated at the cluster level were compared to aggregated individual-level SBD estimates to produce a Mean Squared Error (MSE) estimate for each study site. In order to estimate individual-level SBD coverage, these MSE values were applied to SBD estimates from the control arm of the DeWorm3 trial, where only school-level reporting of SBD coverage had been collected. In each study site, SBD coverage in the school-level datasets was substantially higher than that obtained from individual-level datasets, indicating possible overestimation of school-level SBD coverage. When applying observed MSE to project expected coverages in the control arm, SBD coverage dropped from 89.1% to 70.5% (p-value < 0.001) in Benin, from 97.7% to 84.5% (p-value < 0.001) in India, and from 41.5% to 37.5% (p-value < 0.001) in Malawi.

Conclusions/significance: These estimates indicate that school-level SBD reporting is likely to significantly overestimate program coverage. These findings suggest that current SBD coverage estimates derived from school-based program data may substantially overestimate true pediatric deworming coverage within targeted communities.

Trial registration: NCT03014167.

Fig 1. Histograms of the distance between School Age Children (SAC) and their self-reported schools.

(A) Benin. (B) India. (C) Malawi. The left graph in each panel shows the distribution of the untransformed variable with distance measured in map units, on the right is the log-transformed variable.

Fig 2. Individual-Level Reporting of SBD in Intervention Clusters, by Study Site.

(A) Benin. (B) India. (C) Malawi. Mean SAC Deworming Coverage shown as a red slicer line. Y-Axis set to WHO target of 75% coverage for SAC and PSAC.

Fig 3. Comparison of cluster-level SAC SBD coverage from individual-level data collection to school-level SBD in intervention clusters, by site.

(A) Benin. (B) India. (C) Malawi.

Fig 4. Comparison of school-level SBD coverage estimates to projected SBD coverage estimates in control clusters if individual-level data had been available, by study site.

(A) Benin. (B) India. (C) Malawi.

Fig 5. Comparison of school-level average SBD coverage to average individual-level SBD coverage in control clusters after application of mean-squared error rates.

Fig 6. Catchment areas for each school by study area, created via QGIS Concave Hull (K-nearest neighbor) analysis.

(A) Benin. (B) India. (C) Malawi. The left side of each panel shows naïve catchment areas in semi-transparent pink created prior to removal of geographic outliers, while the right side shows catchment areas in semi-transparent green created after removal of geographic outliers. Both overlay original cluster boundaries in green. Figures created using QGIS 3.10.7 A Coruña.