Sperm chromatin structure assay as an independent predictor of fertility in vivo: a case-control study.

Standard sperm parameters have a limited power for prediction of the chance of natural conception. Recent studies have indicated that the sperm chromatin structure assay (SCSA) DNA fragmentation index (DFI), a measure for the fraction of sperms with DNA damage, is associated with fertility in vivo. The aim of this study was to evaluate the value of this parameter for prediction of infertility. One hundred and twenty-seven men from infertile couples with no known female factor and 137 men with proven fertility were included. Semen analysis was performed as recommended by the WHO. DFI was assessed using SCSA. Logistic binary regression was used to compute the odds ratios (OR) for infertility. As compared with men with a DFI <10%, men with a DFI between 10% and 20% had an increased risk for infertility (OR 2.5, 95% CI: 1.0-6.1). This was also true for men with a DFI >20% (OR 8.4; 95% CI: 3.0-23). In men with normal standard semen parameters (sperm concentration, motility and morphology) the OR for infertility was increased with DFI >20% (OR 5.1, 95% CI: 1.2-23), whereas if one of the standard semen parameters was abnormal, the OR for infertility was increased already at DFI above 10% (OR 16, 95% CI: 4.2-60). We conclude that SCSA DFI adds to the value of semen analysis in prediction of the chance of natural conception.