Estimating intervention effectiveness in trials of malaria interventions with contamination

Multerer, L. and Vanobberghen, F. and Glass, T. R. and Hiscox, A. and Lindsay, S. W. and Takken, W. and Tiono, A. and Smith, T.. (2021) Estimating intervention effectiveness in trials of malaria interventions with contamination. Malar J, 20. p. 413.

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Background In cluster randomized trials (CRTs) or stepped wedge cluster randomized trials (SWCRTs) of malaria interventions, mosquito movement leads to contamination between trial arms unless buffer zones separate the clusters. Contamination can be accounted for in the analysis, yielding an estimate of the contamination range, the distance over which contamination measurably biases the effectiveness. Methods A previously described analysis for CRTs is extended to SWCRTs and estimates of effectiveness are provided as a function of intervention coverage. The methods are applied to two SWCRTs of malaria interventions, the SolarMal trial on the impact of mass trapping of mosquitoes with odor-baited traps and the AvecNet trial on the effect of adding pyriproxyfen to long-lasting insecticidal nets. Results For the SolarMal trial, the contamination range was estimated to be 146 m (95% credible interval [0.052,0.923] km), together with a 31.9% (95% credible interval [15.3,45.8]%) reduction of Plasmodium infection, compared to the 30.0% reduction estimated without accounting for contamination. The estimated effectiveness had an approximately linear relationship with coverage. For the AvecNet trial, estimated contamination effects were minimal, with insufficient data from the cluster boundary regions to estimate the effectiveness as a function of coverage. Conclusions The contamination range in these trials of malaria interventions is much less than the distances Anopheles mosquitoes can fly. An appropriate analysis makes buffer zones unnecessary, enabling the design of more cost-efficient trials. Estimation of the contamination range requires information from the cluster boundary regions and trials should be designed to collect this.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Former Units within Swiss TPH > Infectious Disease Modelling > Epidemiology and Transmission Dynamics (Smith)
UniBasel Contributors:Multerer, Lea and Vanobberghen, Fiona and Glass, Tracy and Smith, Thomas A.
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:20 Dec 2022 14:28
Deposited On:20 Dec 2022 14:28

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