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Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela
BACKGROUND: The ability of cluster-randomized trials to capture mass or indirect effects is one reason for their increasing use to test interventions against vector-borne diseases such as malaria and dengue. For the same reason, however, the independence of clusters may be compromised if the distanc...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7494074/ https://www.ncbi.nlm.nih.gov/pubmed/32881865 http://dx.doi.org/10.1371/journal.pntd.0008576 |
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author | Alexander, Neal Lenhart, Audrey Anaya-Izquierdo, Karim |
author_facet | Alexander, Neal Lenhart, Audrey Anaya-Izquierdo, Karim |
author_sort | Alexander, Neal |
collection | PubMed |
description | BACKGROUND: The ability of cluster-randomized trials to capture mass or indirect effects is one reason for their increasing use to test interventions against vector-borne diseases such as malaria and dengue. For the same reason, however, the independence of clusters may be compromised if the distances between clusters is too small to ensure independence. In other words they may be subject to spillover effects. METHODS: We distinguish two types of spatial spillover effect: between-cluster dependence in outcomes, or spillover dependence; and modification of the intervention effect according to distance to the intervention arm, or spillover indirect effect. We estimate these effects in trial of insecticide-treated materials against the dengue mosquito vector, Aedes aegypti, in Venezuela, the endpoint being the Breteau index. We use a novel random effects Poisson spatial regression model. Spillover dependence is incorporated via an orthogonalized intrinsic conditional autoregression (ICAR) model. Spillover indirect effects are incorporated via the number of locations within a certain radius, set at 200m, that are in the intervention arm. RESULTS: From the model with ICAR spatial dependence, and the degree of surroundedness, the intervention effect is estimated as 0.74—favouring the intervention—with a 95% credible interval of 0.34 to 1.69. The point estimates are stronger with increasing surroundedness within intervention locations. CONCLUSION: In this trial there is some evidence of a spillover indirect effect of the intervention, with the Breteau index tending to be lower in locations which are more surrounded by locations in the intervention arm. |
format | Online Article Text |
id | pubmed-7494074 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-74940742020-09-18 Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela Alexander, Neal Lenhart, Audrey Anaya-Izquierdo, Karim PLoS Negl Trop Dis Research Article BACKGROUND: The ability of cluster-randomized trials to capture mass or indirect effects is one reason for their increasing use to test interventions against vector-borne diseases such as malaria and dengue. For the same reason, however, the independence of clusters may be compromised if the distances between clusters is too small to ensure independence. In other words they may be subject to spillover effects. METHODS: We distinguish two types of spatial spillover effect: between-cluster dependence in outcomes, or spillover dependence; and modification of the intervention effect according to distance to the intervention arm, or spillover indirect effect. We estimate these effects in trial of insecticide-treated materials against the dengue mosquito vector, Aedes aegypti, in Venezuela, the endpoint being the Breteau index. We use a novel random effects Poisson spatial regression model. Spillover dependence is incorporated via an orthogonalized intrinsic conditional autoregression (ICAR) model. Spillover indirect effects are incorporated via the number of locations within a certain radius, set at 200m, that are in the intervention arm. RESULTS: From the model with ICAR spatial dependence, and the degree of surroundedness, the intervention effect is estimated as 0.74—favouring the intervention—with a 95% credible interval of 0.34 to 1.69. The point estimates are stronger with increasing surroundedness within intervention locations. CONCLUSION: In this trial there is some evidence of a spillover indirect effect of the intervention, with the Breteau index tending to be lower in locations which are more surrounded by locations in the intervention arm. Public Library of Science 2020-09-03 /pmc/articles/PMC7494074/ /pubmed/32881865 http://dx.doi.org/10.1371/journal.pntd.0008576 Text en https://creativecommons.org/publicdomain/zero/1.0/ This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 (https://creativecommons.org/publicdomain/zero/1.0/) public domain dedication. |
spellingShingle | Research Article Alexander, Neal Lenhart, Audrey Anaya-Izquierdo, Karim Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela |
title | Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela |
title_full | Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela |
title_fullStr | Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela |
title_full_unstemmed | Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela |
title_short | Spatial spillover analysis of a cluster-randomized trial against dengue vectors in Trujillo, Venezuela |
title_sort | spatial spillover analysis of a cluster-randomized trial against dengue vectors in trujillo, venezuela |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7494074/ https://www.ncbi.nlm.nih.gov/pubmed/32881865 http://dx.doi.org/10.1371/journal.pntd.0008576 |
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