Causal inference for the effect of environmental chemicals on chronic kidney disease

There is evidence from a limited number of statistical and animal studies that suggest that perfluoroalkyl acids (PFAs) are linked to a decline in kidney function. Thus, PFA exposure may be a modifiable risk factor for chronic kidney disease (CKD). As PFA is pervasive throughout our environment, determining its health effects is an important public health concern. We examined cross-sectional data from the 2009-2010 cycle of NHANES using generalized propensity score (GPS) analysis and univariate and multivariate ordinary least squares (OLS) regression to determine the link between urinary PFA concentration and estimated glomerular filtration rate (eGFR). GPS estimation methods used were Hirano-Imbens, additive spline, and a generalized additive model. Each of the statistical models used associated an increase in PFA concentration with a decline in eGFR, though the eGFR fit using the multivariate regression model were consistently higher than from the other four models. We conclude that PFA is a modifiable risk factor for CKD and GPS analysis produces credible results in estimating the effect of chemical exposures on continuous measure of kidney functions such as eGFR. Graphical abstract