Multiple exposure distributed lag models with variable selection

TL;DR

This paper introduces a Bayesian distributed lag model with variable selection to identify critical windows and interactions among multiple environmental exposures affecting health outcomes, demonstrated on air pollution and birthweight data.

Contribution

It develops a novel Bayesian approach with spike-and-slab priors for variable and interaction selection in distributed lag models for environmental exposures.

Findings

Identified key air pollutants affecting birthweight during pregnancy.

Detected interactions between exposures influencing health outcomes.

Extended model improves power to find harmful exposures.

Abstract

Distributed lag models are useful in environmental epidemiology as they allow the user to investigate critical windows of exposure, defined as the time period during which exposure to a pollutant adversely affects health outcomes. Recent studies have focused on estimating the health effects of a large number of environmental exposures, or an environmental mixture, on health outcomes. In such settings, it is important to understand which environmental exposures affect a particular outcome, while acknowledging the possibility that different exposures have different critical windows. Further, in the studies of environmental mixtures, it is important to identify interactions among exposures, and to account for the fact that this interaction may occur between two exposures having different critical windows. Exposure to one exposure early in time could cause an individual to be more or less susceptible to another exposure later in time. We propose a Bayesian model to estimate the temporal effects of a large number of exposures on an outcome. We use spike-and-slab priors and semiparametric distributed lag curves to identify important exposures and exposure interactions, and discuss extensions with improved power to detect harmful exposures. We then apply these methods to estimate the effects of exposure to multiple air pollutants during pregnancy on birthweight from vital records in Colorado.