Reanalysis of cluster randomised trial data to account for exposure misclassification using a per-protocol and complier-restricted approach

Abstract

ABSTRACTThe intention-to-treat (ITT) analysis of the ApplyingWolbachiato Eliminate Dengue (AWED) trial estimated a protective efficacy of 77.1% for participants resident in areas randomised to receive releases ofwMel-infectedAedes aegyptimosquitoes, an emerging dengue preventive intervention. The limiting assumptions of ITT analyses in cluster randomised trials and the mobility of mosquitoes and humans across cluster boundaries indicate the primary analysis is likely to underestimate the full public health benefit. Using spatiotemporally-resolved data on the distribution ofWolbachiamosquitoes and on the mobility of AWED participants (n = 6,306), we perform complier-restricted and per-protocol re-examinations of the efficacy of theWolbachiaintervention. Increased intervention efficacy was estimated in all analyses by the refined exposure measures. The complier-restricted analysis returned an estimated efficacy of 80.7% (95% CI: 65.9, 89.0) and the per-protocol analysis estimated 82.7% (71.7, 88.4) efficacy when comparing participants with an estimatedwMel exposure of≥80% compared to those with<20%. These reanalyses demonstrate how human and mosquito movement can lead to underestimation of intervention effects in trials of vector interventions and indicate that the protective efficacy ofWolbachiais even higher than reported in the primary trial results.