The misdiagnosed mediator: Estimating the effect of maternal age on preterm birth risk in the presence of misclassified gestational hypertension

Music City Center 

The risk of preterm birth increases with maternal age, and it is possible that hypertensive disorders, like gestational hypertension, mediate this maternal age-preterm birth relationship. Previous studies, however, have found low diagnostic accuracy of gestational hypertension. Thus, any mediation analysis conducted with this potentially misclassified binary mediator variable may be severely biased. This bias is especially challenging to address when the misclassification is covariate-dependent and when no gold standard measures are available. In this study, we develop methods to handle misclassification in the gestational hypertension mediator variable by modelling misdiagnosis based on patient-level factors. We present an expectation-maximization algorithm to estimate the model and provide an R package to implement the proposed methods. Using these methods, we assess the misclassification-corrected effect of maternal age on preterm birth risk, while simultaneously estimating misclassification rates of gestational hypertension.

mediation analysis

bias-correction

label switching

EM algorithm

predictive value weighting

causal effects