Table 1.
WHO and Swiss TPH guidelines for quality control of fecal egg counts based on Kato-Katz.
Fig 1.
Overview of the percentage and type of discrepancies observed during the quality control on fecal egg counts.
The proportion and type of discrepancies detected during quality control of duplicate Kato-Katz thick smears are grouped per helminth species. The type of discrepancy (type 1–3) is indicated by color code and is presented per country (BR: Brazil (n = 42); ET; Ethiopia (n = 216); LA: Lao PDR (n = 108); TA: Tanzania (n = 84)) and as a proportion across the four different studies (ALL: all countries combined; n = 450).
Table 2.
Prevalence of any infection and moderate-to-heavy intensity infections before and after quality control on fecal egg counts.
The prevalence of each soil-transmitted helminth in each study site was calculated based on the duplicate Kato-Katz results at baseline using both the original dataset (Pre-QC FEC dataset) as well as that dataset after adjusting for discrepancies detected during quality control (QC) on the fecal egg counts (Post-QC FEC dataset). The infection intensity in both datasets was classified into light and moderate-to-heavy intensity (MHI) according to the thresholds set by the World Health Organization [10]. Values that differ between both datasets are highlighted in bold font.
Table 3.
Egg reduction rates and drug efficacy classification before and after quality control on fecal egg counts.
Using the dataset from Ethiopia, Lao PDR and Tanzania, the egg reduction rates (ERRs) and 95% Confidence Interval (95% CI) were calculated based on the duplicate Kato-Katz data for each soil-transmitted helminth using both the original dataset (Pre-QC FEC) as well as the dataset after adjusting for discrepancies detected during quality control (QC) on the fecal egg counts (FECs) (Post-QC FEC). The ERRs were classified into satisfactory (green), doubtful (yellow) or reduced (red) according to albendazole efficacy thresholds set by the World Health Organization [2].
Table 4.
The number of discrepant data entries revealed by quality control on data entry.
Duplicate Kato-Katz results entered by the two data entry clerks were compared to the corrected dataset and the number of discrepancies were reported.
Table 5.
Prevalence of any infection and moderate-to-heavy intensity infections before and after quality control on data entry.
For each country and species of soil-transmitted helminth, the prevalence of any infection and moderate-to-heavy intensity (MHI) infections and the egg reduction rates (ERRs) following single albendazole treatment were calculated. This was done using the raw duplicate Kato-Katz data provided by data entry person 1 (P1), data entry person 2 (P2) and the dataset corrected for possible data entry errors (Corrected). The ERRs were classified into satisfactory (green), doubtful (yellow) or reduced (red) according to albendazole efficacy thresholds set by the World Health Organization [2]. Values that differ from the values obtained by analyzing the corrected database are highlighted in bold.