Multivariate discriminate analysis of the relationship between the hypo‐osmotic swelling test and the in‐vitro fertilizing capacity of human sperm

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Abstract
Summary: Multivariate discriminant analysis was used to evaluate the usefulness of routine semen parameters and the hypo‐osmotic swelling test (HOST) as predictors of the in‐vitro fertilizing capacity of human sperm as assessed by the zona‐free hamster egg penetration assay (HEPA). Eighty‐eight semen samples from untreated patients attending an infertility clinic were analysed. Semen samples were classified into the following three groups before statistical analysis: group l—positive sperm penetration (≥10%, >n = 39); group 2—rderline penetration rates for HEPA (>0 but n= 39) and group 3—gative sperm penetration (0, n= 10). The percentage of sperm with normal morphology and sperm count were found to be significant in discriminating between semen samples exhibiting different in‐vitro fertilizing capacity. These two discriminating variables in combination gave an overall correct classification rate of 45.5%. The multivariate discriminant analysis was also performed after excluding the data of group 2 semen samples (n= 39), which exhibited borderline sperm penetration rates. As a result, three discriminating variables including semen volume, sperm count and the percentage of sperm with normal morphology were selected. These three variables in combination could accurately predict whether a semen sample would exhibit positive sperm penetration (group 1) or negative sperm penetration (group 3) with an overall accuracy of 75.5%. The percentage of swollen sperm after hypo‐osmotic treatment was not related to the HEPA result, as determined by linear correlation and multiple regression analyses, and did not give additional information about the in‐vitro fertilizing capacity of sperm as evaluated by multivariate discriminant analysis.