Survey Design to Monitor Drug Efficacy for the Control of Soil-Transmitted Helminthiasis and Schistosomiasis
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Survey Design to Monitor Drug Efficacy for the Control of Soil-Transmitted Helminthiasis and Schistosomiasis. / Coffeng, Luc E.; Levecke, Bruno; Hattendorf, Jan; Walker, Martin; Denwood, Matthew J.
I: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, Bind 72, Nr. 3, 2021, s. S195-S202.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Survey Design to Monitor Drug Efficacy for the Control of Soil-Transmitted Helminthiasis and Schistosomiasis
AU - Coffeng, Luc E.
AU - Levecke, Bruno
AU - Hattendorf, Jan
AU - Walker, Martin
AU - Denwood, Matthew J.
N1 - Publisher Copyright: © The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America.
PY - 2021
Y1 - 2021
N2 - 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.
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.
KW - drug efficacy
KW - health economics
KW - schistosomiasis
KW - soil-transmitted helminthiasis
KW - survey design
U2 - 10.1093/cid/ciab196
DO - 10.1093/cid/ciab196
M3 - Journal article
C2 - 33906226
AN - SCOPUS:85108304207
VL - 72
SP - S195-S202
JO - Clinical Infectious Diseases
JF - Clinical Infectious Diseases
SN - 1058-4838
IS - 3
ER -
ID: 273297464