Claire Philippat1, Antonia M Calafat2. 1. University Grenoble Alpes, Inserm, CNRS, Team of Environmental Epidemiology Applied to Reproduction and Respiratory Health, Institute for Advanced Biosciences (IAB), Grenoble, France. Electronic address: claire.philippat@inserm.fr. 2. Centers for Disease Control and Prevention, Atlanta, GA, USA.
Abstract
BACKGROUND: In biomarker-based studies, collecting repeated biospecimens per participant can decrease measurement error, particularly for biomarkers displaying high within-subject variability. Guidelines to combine such repeated biospecimens do not exist. AIMS: To compare the efficiency of several designs relying on repeated biospecimens to estimate exposure over 7 days. METHODS: We quantified triclosan and bisphenol A (BPA) in all urine voids (N = 427) collected over seven days from eight individuals. We estimated the volume-weighted concentrations for all urine samples collected during a week and compared these gold standards with the concentrations obtained for equal-volume pools (standardized or not for urine dilution), unequal-volume pools (based on sample volume or creatinine concentration), and for the mean of the creatinine-standardized concentrations measured in each spot sample. RESULTS: For both chemicals, correlations with gold standards were similar for equal- and unequal-volume pooling designs. Only for BPA, correlation coefficients were markedly lower after standardization for specific gravity or creatinine of concentrations estimated in equal-volume pools. Averaging BPA creatinine-standardized concentrations measured in each spot sample led also to lower correlations with gold standards compared to those obtained for unstandardized pooling designs. CONCLUSION: For BPA and triclosan, considering individual urine sample volume or creatinine concentrations when pooling is unnecessary because equal-volume pool adequately estimates concentrations in gold standards. Standardization for specific gravity or creatinine of the concentrations assessed in equal-volume pool as well as averaging creatinine-standardized concentrations measured in each individual spot sample are not suitable for BPA. These results provide a practical framework on how to combine repeated biospecimens in epidemiological studies.
BACKGROUND: In biomarker-based studies, collecting repeated biospecimens per participant can decrease measurement error, particularly for biomarkers displaying high within-subject variability. Guidelines to combine such repeated biospecimens do not exist. AIMS: To compare the efficiency of several designs relying on repeated biospecimens to estimate exposure over 7 days. METHODS: We quantified triclosan and bisphenol A (BPA) in all urine voids (N = 427) collected over seven days from eight individuals. We estimated the volume-weighted concentrations for all urine samples collected during a week and compared these gold standards with the concentrations obtained for equal-volume pools (standardized or not for urine dilution), unequal-volume pools (based on sample volume or creatinine concentration), and for the mean of the creatinine-standardized concentrations measured in each spot sample. RESULTS: For both chemicals, correlations with gold standards were similar for equal- and unequal-volume pooling designs. Only for BPA, correlation coefficients were markedly lower after standardization for specific gravity or creatinine of concentrations estimated in equal-volume pools. Averaging BPA creatinine-standardized concentrations measured in each spot sample led also to lower correlations with gold standards compared to those obtained for unstandardized pooling designs. CONCLUSION: For BPA and triclosan, considering individual urine sample volume or creatinine concentrations when pooling is unnecessary because equal-volume pool adequately estimates concentrations in gold standards. Standardization for specific gravity or creatinine of the concentrations assessed in equal-volume pool as well as averaging creatinine-standardized concentrations measured in each individual spot sample are not suitable for BPA. These results provide a practical framework on how to combine repeated biospecimens in epidemiological studies.
Authors: Holger M Koch; Lesa L Aylward; Sean M Hays; Roel Smolders; Rebecca K Moos; John Cocker; Kate Jones; Nicholas Warren; Len Levy; Ruth Bevan Journal: Toxicol Lett Date: 2014-06-20 Impact factor: 4.372
Authors: Joe M Braun; Amy E Kalkbrenner; Antonia M Calafat; Kimberly Yolton; Xiaoyun Ye; Kim N Dietrich; Bruce P Lanphear Journal: Pediatrics Date: 2011-10-24 Impact factor: 7.124
Authors: John D Meeker; David E Cantonwine; Luis O Rivera-González; Kelly K Ferguson; Bhramar Mukherjee; Antonia M Calafat; Xiaoyun Ye; Liza V Anzalota Del Toro; Noé Crespo-Hernández; Braulio Jiménez-Vélez; Akram N Alshawabkeh; José F Cordero Journal: Environ Sci Technol Date: 2013-03-19 Impact factor: 9.028
Authors: Daniel R S Middleton; Michael J Watts; R Murray Lark; Chris J Milne; David A Polya Journal: Environ Health Date: 2016-06-10 Impact factor: 5.984
Authors: Michiel A van den Dries; Alexander P Keil; Henning Tiemeier; Anjoeka Pronk; Suzanne Spaan; Susana Santos; Alexandros G Asimakopoulos; Kurunthachalam Kannan; Romy Gaillard; Mònica Guxens; Leonardo Trasande; Vincent W V Jaddoe; Kelly K Ferguson Journal: Environ Health Perspect Date: 2021-11-24 Impact factor: 9.031