Statistical Methods For Assessing The Health Of Sperm

Environmental Health Sciences

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Abstract

We are developing improved methods for assessing the health of sperm, both for application to reproductive toxicology studies and for development of improved biomarkers for human male fertility. Work has progressed in the development of methods for assessing treatment effects on multiple measures of sperm motility, including both the proportion of motile sperm in a sample and the movement characteristics of the individual motile sperm. Proper characterization of the motion of sperm is needed to detect and interpret effects of male exposures to reproductive toxicants. Large numbers of sperm can be individually tracked using computer-assisted semen analysis (CASA), which records X-Y coordinates of the planar projection of the sperm's path over approximately one second, and outputs seven summary measures describing that track. A method we developed previously summarizes the motion of an individual sperm using three measures. In the presence of an effect of a toxicant on sperm survival, assessments based on the motility of the surviving sperm may be biased, since sperm that do not survive may have had low motility in the absence of exposure. We have developed a general approach for jointly assessing effects on survival and the motility of the survivors.