Imperial College London
Alternate

DrMartinWalker

Faculty of Medicine, School of Public Health

Honorary Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 3229m.walker06 CV

 
 
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Location

 

G2716 South Wharf RoadSt Mary's Campus

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Summary

 

Publications

Citation

BibTex format

@article{Coffeng:2021:cid/ciab196,
author = {Coffeng, LE and Levecke, B and Hattendorf, J and Walker, M and Denwood, MJ},
doi = {cid/ciab196},
journal = {Clinical Infectious Diseases},
pages = {S195--S202},
title = {Survey design to monitor drug efficacy for the control of soil-transmitted helminthiasis and schistosomiasis.},
url = {http://dx.doi.org/10.1093/cid/ciab196},
volume = {72},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - BACKGROUND: Control of soil-transmitted helminthiasis and schistosomiasis relies heavily on regular preventive chemotherapy. Monitoring drug efficacy is crucial to provide early warning of treatment failures. The World Health Organization (WHO) recommends a survey design in which only egg-positive individuals are retested after treatment. Although this practice makes more efficient use of resources, it may lead to biased drug efficacy estimates. METHODS: We performed a simulation study to assess the potential for bias when evaluating drug efficacy using the World Health Organization-recommended survey design, and to identify alternative designs for evaluating drug efficacy that are less affected by bias. These designs were also based on selection of egg-positive individuals, but involve retesting them a second time at baseline and up to 2 times at follow-up. The utility of the different designs was compared fairly by constraining them to the same budget. RESULTS: The standard procedure of selecting egg-positive individuals can introduce a substantial positive bias in drug efficacy due to regression toward the mean, particularly when infection levels or drug efficacy are low. This bias was completely eliminated by using a second baseline sample, conditionally on the first sample being excluded from analysis. Precision of estimates can be improved by increasing the number of thick smears and/or samples per person at follow-up, despite fewer individuals being tested within the same budget. CONCLUSIONS: We present optimized survey designs to monitor drug efficacy in field settings, which are highly relevant for sustained control of soil-transmitted helminths and schistosomiasis, as well as onchocerciasis and lymphatic filariasis.
AU  - Coffeng,LE
AU  - Levecke,B
AU  - Hattendorf,J
AU  - Walker,M
AU  - Denwood,MJ
DO  - cid/ciab196
EP  - 202
PY  - 2021///
SN  - 1058-4838
SP  - 195
TI  - Survey design to monitor drug efficacy for the control of soil-transmitted helminthiasis and schistosomiasis.
T2  - Clinical Infectious Diseases
UR  - http://dx.doi.org/10.1093/cid/ciab196
UR  - https://www.ncbi.nlm.nih.gov/pubmed/33906226
UR  - https://academic.oup.com/cid/article/72/Supplement_3/S195/6255959
UR  - http://hdl.handle.net/10044/1/104691
VL  - 72
ER  -
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