Associations between Perfluoroalkyl Substances and Systemic Lupus Erythematosus in Gullah African Americans Open Access

Jacob Hojnacki (Spring 2018)

Permanent URL: https://etd.library.emory.edu/concern/etds/xp68kg28j?locale=en
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Abstract

Objective: To assess associations between perfluoroalkyl substances (PFAS) and systemic lupus erythematosus (SLE) incidence in Gullah African Americans.

 

Methods: We analyzed a cross-sectional sample of 42 prevalent SLE cases and 104 persons without SLE at time of enrollment in the Systemic Lupus Erythematosus in Gullah Health (SLEIGH) study as a nested case-control study, with some measurement error on historical exposures and confounders since measures were from a time period after the etiologically relevant time window. PFAS biomarkers, disease status, and potential confounders were measured at the SLEIGH baseline visit. Taking into consideration age at diagnosis, we re-conceptualized this cross-sectional sample as a cohort using age as our time axis, with follow-up of cases ending at age of SLE diagnosis, and disease-free participants’ follow-up censored at age at the SLEIGH baseline visit. We then used risk-set sampling of that cohort, matching 3 participants of the same sex as the case, who had not yet developed SLE (thus, older), to each case. We used conditional logistic regression to estimate the odds ratios of lupus as a function of each PFAS, controlling for baseline visit age, family history of SLE, ever/never smoking, educational attainment, and serum albumin. Conditioning on albumin was intended to block the path from disease to measured PFAS as surrogate of past PFAS. Baseline education was a proxy for unmeasured socioeconomic factors.

 

Results: A 1 ng/mL serum increase PFHxS was positively associated with lupus (Odds Ratio = 1.70, 95% Confidence Interval 1.00, 2.89), as was a 1 ng/mL serum increase in PFOA (OR=1.30, 95% CI 1.00, 1.68).

 

Conclusion: This observational study suggests that some PFAS may be positively associated with SLE incidence, after controlling for albumin and measured confounders, and making several strong assumptions. This analysis should be viewed as exploratory and tested for replication in a larger sample with prospective exposure assessment.

 

Table of Contents

INTRODUCTION.......................................................................................................... 1

METHODS.................................................................................................................. 4

SOURCE POPULATION........................................................................................................ 4

OUTCOME ASSESMENT......................................................................................................... 4

EXPOSURE ASSESMENT......................................................................................................... 5

DATA ON OTHER VARIABLES.......................................................................................................... 5

STUDY SAMPLE............................................................................................................... 5

STATISTICAL APPROACH........................................................................................................... 6

RESULTS................................................................................................................... 8

PARTICIPANT CHARACTERISTICS..................................................................................................... 8

ASSOCIATIONS OF PFAS WITH SLE.......................................................................................................................... 9

DISCUSSION............................................................................................................. 11

CONCLUSIONS .......................................................................................................................................... 15

SUPPLEMENTAL MATERIALS ............................................................................................................. 16

REFERENCES ............................................................................................................................................ 21

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