Quality of semen: a 6-year single experience study on 5680 patients

BACKGROUND: The aim of our study was to evaluate the quality of semen of a large sample from general healthy population living in Italy, in order to identify possible variables that could influence several parameters of spermiogram. METHODS: We conducted a cross-sectional study from February 2010 to March 2015, collecting semen samples from the general population. Semen analysis was performed according to the WHO guidelines. The collected data were inserted in a database and processed using the software Stata 12. The Mann-Whitney Test was used to assess the relationship of dichotomus variables with the parameters of the spermiogram; Kruskal-Wallis Test for variables with more than two categories. We used also Robust regression and Spearman correlation to analyze the relationship between age and the parameters. RESULTS: We collected 5680 samples of semen. The mean age of our patients was 41.4 years old. Mann-Whitney Test showed that the citizenship (codified as "Italian/Foreign") influences some parameters: pH. vitality, number of spermatozoa, sperm concentration, with worse results for the Italian group. Kruskal-Wallis Test showed that the single nationality influences pH, volume, sperm motility A-B-C-D. vitality, morphology, number of spermatozoa, sperm concentration. Robust regression showed a relationship between age and several parameters: volume (P=0.04, R-2=0.0007 beta: -0.06); sperm motility A (P<0.01; R-2=0.0051;beta=0.02); sperm motility B (P<0.01; R-2=0.02; beta=-0.35); sperm motility C (P<0.01; R-2=0.01; beta=0.12); sperm motility D (P<0.01; R-2=0.006; beta=0.2); vitality (P<0.01; R-2=0.011; beta=-0.32) ; sperm concentration (P=0.01; R-2=0.001;beta=0.19). CONCLUSIONS: Our patients had spenniogram's results quite better than the standard guidelines. Our study showed that the country of origin could be a factor influencing several parameters of the spermiogram in healthy population and through robust regression confirmed a strict correlation between age and these parameters.