Sensitivity analysis for unobserved confounding of direct and indirect effects using uncertainty intervals. (20th February 2018)

• Record Type: Journal Article
• Authors: Lindmark, Anita; de Luna, Xavier; Eriksson, Marie
• Is Part Of: Statistics in medicine. Volume 37:Number 10(2018)
• Page Start: 1744
• Page End: 1762
• Publication Date: 2018-02-20
• Subjects: direct effects -- indirect effects -- mediation -- sensitivity analysis -- sequential ignorability -- unmeasured confounding; Medical statistics -- Periodicals; Statistique médicale -- Périodiques; Statistiques médicales -- Périodiques; 610.727
• DOI: 10.1002/sim.7620
• Languages: English
• ISSNs: 0277-6715

Abstract

Abstract : To estimate direct and indirect effects of an exposure on an outcome from observed data, strong assumptions about unconfoundedness are required. Since these assumptions cannot be tested using the observed data, a mediation analysis should always be accompanied by a sensitivity analysis of the resulting estimates. In this article, we propose a sensitivity analysis method for parametric estimation of direct and indirect effects when the exposure, mediator, and outcome are all binary. The sensitivity parameters consist of the correlations between the error terms of the exposure, mediator, and outcome models. These correlations are incorporated into the estimation of the model parameters and identification sets are then obtained for the direct and indirect effects for a range of plausible correlation values. We take the sampling variability into account through the construction of uncertainty intervals. The proposed method is able to assess sensitivity to both mediator‐outcome confounding and confounding involving the exposure. To illustrate the method, we apply it to a mediation study based on the data from the Swedish Stroke Register (Riksstroke). An R package that implements the proposed method is available.