Online Program Home
My Program

Abstract Details

Activity Number: 360 - Contributed Poster Presentations: ENAR
Type: Contributed
Date/Time: Tuesday, July 31, 2018 : 10:30 AM to 12:20 PM
Sponsor: ENAR
Abstract #328367
Title: Strategies for Adjusting for Urinary Creatinine or Serum Lipids When Exposure Is Measured on Pooled Specimens
Author(s): Min Shi* and Clarice Weinberg and David Umbach and Katie O'Brien
Companies: NIEHS and National Institute of Environmental Health Sciences and National Institute of Environmental Health Sciences and National Institute of Environmental Health Sciences
Keywords: pooling; case-control study; limit of detection; creatinine

Assays of biomarkers of exposure can sometimes be prohibitively expensive. For a case-control study, pooling equal aliquots of specimens before assay is an effective strategy with several important advantages. There is, however, a vexing problem with pooling: One would normally adjust individually-assayed urinary measurements for diluteness of the urine, typically by dividing by creatinine, and similarly adjust serum levels of a lipophyllic analyte by dividing by the serum total lipid level. Unfortunately, one cannot simply divide the analyte concentration measured in a pooled specimen by the creatinine (lipid) concentration found in the pool, because the ratio of means is not the same as the mean of the corresponding ratios. Our proposed remedy requires individual-specimen measurements for creatinine (lipid). One then either physically dilutes the specimens before pooling, to equalize creatinine or lipid levels across specimens in each pooling set, or pools together aliquots of algebraically-determined unequal volumes and then adjusts the pooled concentration using the individual-specimen creatinine (lipid) values. We assess performance of the approaches via simulations.

Authors who are presenting talks have a * after their name.

Back to the full JSM 2018 program