Spatial regression and spillover effects in cluster randomized trials with count outcomes

Karim Anaya-Izquierdo, Neal Alexander

Research output: Contribution to journalArticlepeer-review

2 Citations (SciVal)

Abstract

This paper describes methodology for analyzing data from cluster randomized trials with count outcomes, taking indirect effects as well spatial effects into account. Indirect effects are modelled using a novel application of a measure of depth within the intervention arm. Both direct and indirect effects can be estimated accurately even when the proposed model is misspecified. We use spatial regression models with Gaussian random effects, where the individual outcomes have distributions overdispersed with respect to the Poisson, and the corresponding direct
and indirect effects have a marginal interpretation. To avoid spatial confounding, we use orthogonal regression, in which random effects represent spatial dependence using a homoscedastic and dimensionally-reduced modification
of the intrinsic conditional autoregression (ICAR) model. We illustrate the methodology using spatial data from a pair-matched cluster randomized trial against the dengue mosquito vector Aedes aegypti, done in Trujillo, Venezuela
Original languageEnglish
Pages (from-to)490-505
JournalBiometrics
Volume77
Issue number2
Early online date18 Jun 2020
DOIs
Publication statusPublished - 1 Jun 2021

Bibliographical note

Funding Information:
This work was supported by the United Kingdom Medical Research Council (MRC) via Grant Reference G7508177, also by MRC and the UK Department for International Development (DFID), MRC Grant References MR/K012126/1 and MR/R010161/1, awards jointly funded by the MRC and DFID under the MRC/DFID Concordat agreement and also part of the EDCTP2 programme supported by the European Union. We also thank Christian Bottomley for helpful suggestions, Valeria Simoncini for guidance on iterative projection algorithms, and anonymous referees for useful suggestions.

Publisher Copyright:
© 2020 The Authors. Biometrics published by Wiley Periodicals, LLC on behalf of International Biometric Society.

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