An Empirical Validation of the Within-subject Biospecimens Pooling Approach to Minimize Exposure Misclassification in Biomarker-based Studies

• Published in: Epidemiology (Cambridge, Mass.) Vol. 30; no. 5; p. 756
• Main Authors: Vernet, Céline, Philippat, Claire, Agier, Lydiane, Calafat, Antonia M, Ye, Xiaoyun, Lyon-Caen, Sarah, Hainaut, Pierre, Siroux, Valérie, Schisterman, Enrique F, Slama, Rémy
• Format: Journal Article
• Language: English
• Published: United States 01.09.2019
• Subjects: Adult; Bias; Biomarkers - urine; Environmental Exposure - analysis; Environmental Monitoring - methods; Environmental Pollutants - urine; Epidemiologic Research Design; Female; Follow-Up Studies; Humans; Phenols - urine; Pregnancy; Reproducibility of Results
• ISSN: 1531-5487
• DOI: 10.1097/EDE.0000000000001056

Within-subject biospecimens pooling can theoretically reduce bias in dose-response functions from biomarker-based studies when exposure assessment suffers from classical-type error. However, collecting many urine voids each day is cumbersome. We evaluated the empirical validity of a within-subject pooling approach and compared several options to avoid sampling each void. In 16 pregnant women who collected a spot of each urine void over several nonconsecutive weeks, we compared concentrations of 10 phenols in daily, weekly, and pregnancy within-subject pools. We pooled either three or all daily samples. In a simulation study using these data, we quantified bias in dose-response functions when using one to 20 urine samples per subject to assess methylparaben (a compound with moderate within-subject variability) and bisphenol A (high variability) exposures. Correlations between exposure estimates from pools of all and of only three voids per day were above 0.80 for all time windows and compounds, except for benzophenone-3 and triclosan in the daily time window (correlations, 0.57-0.68). With one spot sample to assess pregnancy exposure, correlations were all below 0.74. Using only one biospecimen led to attenuation bias in the dose-response functions of 29% (methylparaben) and 69% (bisphenol A); four samples for methylparaben and 18 for bisphenol A decreased bias to 10%. For nonpersistent chemicals, collecting and pooling three samples per day instead of all daily samples efficiently estimates exposures over a week or more. Collecting around 20 biospecimens can strongly limit attenuation bias for nonpersistent chemicals such as bisphenol A.