Principal investigator: Enrique F. Schisterman, Ph.D.
New biomarkers of exposure and disease status are being developed daily for clinical and research purposes. However, the considerable monetary cost of evaluating some of these new and very promising biomarkers has led investigators to restrict their choice of which biomarkers are going to be evaluated. Their decision is usually based on a small dataset and laboratory costs. If a biomarker could be shown to have a strong discriminating power or is strongly related to disease status, the development of less expensive measurement techniques of this marker would be encouraged or the use of more resources to examine this hypothesis would be justified. Pooling biological specimens of different individuals and testing only groups is a cost-saving alternative for screening and exposure assessment. Umbach and Weinberg introduced pooling as a means to improve efficiency in case-control studies to estimate odds ratios. This research examined the effect of pooling on the efficiency of the estimation of the area under the ROC curve, a measure of discriminating power. Also, researchers extended this work and developed a method to compare the areas under the ROC curve for several markers, the optimal cut point, the evaluation of distributional assumptions, and sample size calculation formulas for the design of new studies.
 
DESPR Collaborators

· Aiyi Liu, Ph.D.
· Neil Perkins, Ph.D.
 
Selected Publications

Vexler A, Schisterman EF, & Liu A. (2008). Estimation of ROC curves based on stably distributed biomarkers subject to measurement error and pooling mixtures. Statistics in Medicine, 27(2):280-296. [Abstract]

Vexler A, Liu A, & Schisterman EF. (2006). Efficient design and analysis of biospecimens with measurements subject to detection limit. Biometrical Journal, 48:780-91.  [Abstract]

Mumford SL, Schisterman EF, Vexler A, & Liu A. (2006). Pooling biospecimens and limits of detection: effects on ROC curve analysis. Biostatistics, 7:585-598. [Abstract]

Schisterman EF, Vexler A, Whitcomb BW, & Liu A. (2006). The limitations due to exposure detection limits for regression models. American Journal of Epidemiology, 163:374-383. [Abstract]

Bondell H, Liu A, & Schisterman EF. (2007). Statistical inference based on pooled data: a moment-based estimating equation approach. Journal of Applied Statistics, 34: 129-140.

Schisterman EF, Perkins N, Liu A, & Bondell H. (2005). Optimal cut-point and its corresponding Youden Index to discriminate individuals using pooled blood samples. Epidemiology, 16(1):73-81. [Abstract]

Liu A, Schisterman EF, & Theo E. (2004). Sample size and power calculation in comparing diagnostic accuracy of biomarkers with pooled assessments. Journal of Applied Statistics, 31:49-59. (Authorship in alphabetical order)

Faraggi D, Reiser B, & Schisterman EF. (2003). ROC curve analysis for biomarkers based on pooled assessments. Statistics in Medicine, 22:2515-2527. (Authorship in alphabetical order) [Abstract]

Liu A & Schisterman EF. (2003). Comparison of diagnostic accuracy of biomarkers with pooled assessments. Biometrical Journal, 45:631-644. (Authorship in alphabetical order)