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U.S. Department of Health and Human Services

Scientific Publications by FDA Staff

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J Urol 2013 May;189(5):1825-9

Variability of semen parameters with time in placebo treated men.

Jarow JP, Fang X, Hammad TA


PURPOSE: To describe the variability of semen parameters in normal men receiving placebo over time and the impact of season and geographic region, among other variables, on these parameters. MATERIALS AND METHODS: The data from the placebo arms of five randomized controlled trials were pooled. All of the trials set minimum standards for semen parameters as an eligibility criterion for entry. Semen parameters examined include volume, density, motility, total count, total motile count, and morphology. Mixed model repeated measure analysis was utilized for statistical analysis. Coefficients of variation for each semen parameter and percent change from baseline were calculated. RESULTS: The mean within-subject coefficient of variation for each semen parameter ranged from a low of 10% to a high of almost 50%. The contribution of season and region to variability was negligible. The reduction of variability with increasing number of samples per time point had diminishing returns beyond two samples. CONCLUSIONS: There is considerable variation in semen parameters over time within subjects receiving placebo that could not be attributed to either season or region. We observed a general negative trend for the semen parameters in this population selected for "normal" baseline semen parameters that is likely due to placebo response or regression toward the mean.

Category: Journal Article
PubMed ID: #23159587 DOI: 10.1016/j.juro.2012.11.077
Includes FDA Authors from Scientific Area(s): Drugs
Entry Created: 2012-11-21 Entry Last Modified: 2013-10-17