Cargando…
Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs
BACKGROUND: The fecal egg count reduction test (FECRT) is recommended to monitor drug efficacy against soil-transmitted helminths (STHs) in public health. However, the impact of factors inherent to study design (sample size and detection limit of the fecal egg count (FEC) method) and host-parasite i...
Autores principales: | , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2011
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3236725/ https://www.ncbi.nlm.nih.gov/pubmed/22180801 http://dx.doi.org/10.1371/journal.pntd.0001427 |
_version_ | 1782218774095593472 |
---|---|
author | Levecke, Bruno Speybroeck, Niko Dobson, Robert J. Vercruysse, Jozef Charlier, Johannes |
author_facet | Levecke, Bruno Speybroeck, Niko Dobson, Robert J. Vercruysse, Jozef Charlier, Johannes |
author_sort | Levecke, Bruno |
collection | PubMed |
description | BACKGROUND: The fecal egg count reduction test (FECRT) is recommended to monitor drug efficacy against soil-transmitted helminths (STHs) in public health. However, the impact of factors inherent to study design (sample size and detection limit of the fecal egg count (FEC) method) and host-parasite interactions (mean baseline FEC and aggregation of FEC across host population) on the reliability of FECRT is poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: A simulation study was performed in which FECRT was assessed under varying conditions of the aforementioned factors. Classification trees were built to explore critical values for these factors required to obtain conclusive FECRT results. The outcome of this analysis was subsequently validated on five efficacy trials across Africa, Asia, and Latin America. Unsatisfactory (<85.0%) sensitivity and specificity results to detect reduced efficacy were found if sample sizes were small (<10) or if sample sizes were moderate (10–49) combined with highly aggregated FEC (k<0.25). FECRT remained inconclusive under any evaluated condition for drug efficacies ranging from 87.5% to 92.5% for a reduced-efficacy-threshold of 90% and from 92.5% to 97.5% for a threshold of 95%. The most discriminatory study design required 200 subjects independent of STH status (including subjects who are not excreting eggs). For this sample size, the detection limit of the FEC method and the level of aggregation of the FEC did not affect the interpretation of the FECRT. Only for a threshold of 90%, mean baseline FEC <150 eggs per gram of stool led to a reduced discriminatory power. CONCLUSIONS/SIGNIFICANCE: This study confirms that the interpretation of FECRT is affected by a complex interplay of factors inherent to both study design and host-parasite interactions. The results also highlight that revision of the current World Health Organization guidelines to monitor drug efficacy is indicated. We, therefore, propose novel guidelines to support future monitoring programs. |
format | Online Article Text |
id | pubmed-3236725 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2011 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-32367252011-12-16 Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs Levecke, Bruno Speybroeck, Niko Dobson, Robert J. Vercruysse, Jozef Charlier, Johannes PLoS Negl Trop Dis Research Article BACKGROUND: The fecal egg count reduction test (FECRT) is recommended to monitor drug efficacy against soil-transmitted helminths (STHs) in public health. However, the impact of factors inherent to study design (sample size and detection limit of the fecal egg count (FEC) method) and host-parasite interactions (mean baseline FEC and aggregation of FEC across host population) on the reliability of FECRT is poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: A simulation study was performed in which FECRT was assessed under varying conditions of the aforementioned factors. Classification trees were built to explore critical values for these factors required to obtain conclusive FECRT results. The outcome of this analysis was subsequently validated on five efficacy trials across Africa, Asia, and Latin America. Unsatisfactory (<85.0%) sensitivity and specificity results to detect reduced efficacy were found if sample sizes were small (<10) or if sample sizes were moderate (10–49) combined with highly aggregated FEC (k<0.25). FECRT remained inconclusive under any evaluated condition for drug efficacies ranging from 87.5% to 92.5% for a reduced-efficacy-threshold of 90% and from 92.5% to 97.5% for a threshold of 95%. The most discriminatory study design required 200 subjects independent of STH status (including subjects who are not excreting eggs). For this sample size, the detection limit of the FEC method and the level of aggregation of the FEC did not affect the interpretation of the FECRT. Only for a threshold of 90%, mean baseline FEC <150 eggs per gram of stool led to a reduced discriminatory power. CONCLUSIONS/SIGNIFICANCE: This study confirms that the interpretation of FECRT is affected by a complex interplay of factors inherent to both study design and host-parasite interactions. The results also highlight that revision of the current World Health Organization guidelines to monitor drug efficacy is indicated. We, therefore, propose novel guidelines to support future monitoring programs. Public Library of Science 2011-12-13 /pmc/articles/PMC3236725/ /pubmed/22180801 http://dx.doi.org/10.1371/journal.pntd.0001427 Text en Levecke et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. |
spellingShingle | Research Article Levecke, Bruno Speybroeck, Niko Dobson, Robert J. Vercruysse, Jozef Charlier, Johannes Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs |
title | Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs |
title_full | Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs |
title_fullStr | Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs |
title_full_unstemmed | Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs |
title_short | Novel Insights in the Fecal Egg Count Reduction Test for Monitoring Drug Efficacy against Soil-Transmitted Helminths in Large-Scale Treatment Programs |
title_sort | novel insights in the fecal egg count reduction test for monitoring drug efficacy against soil-transmitted helminths in large-scale treatment programs |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3236725/ https://www.ncbi.nlm.nih.gov/pubmed/22180801 http://dx.doi.org/10.1371/journal.pntd.0001427 |
work_keys_str_mv | AT leveckebruno novelinsightsinthefecaleggcountreductiontestformonitoringdrugefficacyagainstsoiltransmittedhelminthsinlargescaletreatmentprograms AT speybroeckniko novelinsightsinthefecaleggcountreductiontestformonitoringdrugefficacyagainstsoiltransmittedhelminthsinlargescaletreatmentprograms AT dobsonrobertj novelinsightsinthefecaleggcountreductiontestformonitoringdrugefficacyagainstsoiltransmittedhelminthsinlargescaletreatmentprograms AT vercruyssejozef novelinsightsinthefecaleggcountreductiontestformonitoringdrugefficacyagainstsoiltransmittedhelminthsinlargescaletreatmentprograms AT charlierjohannes novelinsightsinthefecaleggcountreductiontestformonitoringdrugefficacyagainstsoiltransmittedhelminthsinlargescaletreatmentprograms |