Reproductive Medicine Centre, Skåne University Hospital, Lund University, SE- 205 02 Malmö, Sweden.
Hum Reprod. 2011 Dec;26(12):3244-8. doi: 10.1093/humrep/der328. Epub 2011 Oct 6.
The sperm chromatin structure assay (SCSA) is a valuable tool for prediction of fertility in vivo, with DNA fragmentation index (DFI) of 30% as a clinically useful cut-off level. Previous studies on fertile men have shown a high level of repeatability, with an intra-individual variability in DFI of ≈ 10%. However, conflicting data on how much the DFI fluctuates within individuals exist. The aim of the present study was to investigate the intra-individual variation of DFI in order to further evaluate the clinical use of SCSA.
Among 2409 consecutive men under infertility investigation, repeated SCSA analyses were performed on 616 samples from men between 18 and 66 years of age. The coefficient of variation (CV) for DFI was calculated. For each patient, we also analyzed whether the DFI value in tests I and II switched the category from <30 to >30%, or vice versa.
Mean CV for DFI for men with at least two SCSA analyses within a 30-month period was 30.1% (SD 21.5). Compared with the first test, 85% (95% confidence interval: 82-87%) of the men remained on the same side of the cut-off point of 30%.
Despite showing a high intra-individual CV for DFI, 85% of the men from infertile couples did not change category between tests, with respect to the cut-off level of 30%. Thus, using the previously established DFI cut-off value of 30%, a single SCSA analysis has a high predictive value for assessing fertility in vivo.
精子染色质结构分析（SCSA）是预测体内生育能力的一种有价值的工具，30%的 DNA 碎片指数（DFI）作为一个临床有用的截止值。先前对生育能力正常男性的研究表明，DFI 具有高度的可重复性，个体内的变异度约为 10%。然而，关于个体内 DFI 的波动程度存在相互矛盾的数据。本研究旨在调查 DFI 的个体内变异性，以进一步评估 SCSA 的临床应用。
在 2409 例连续进行不孕检查的男性中，对 18 至 66 岁的 616 例男性的样本进行了重复的 SCSA 分析。计算 DFI 的变异系数（CV）。对于每个患者，我们还分析了测试 I 和 II 中的 DFI 值是否将类别从<30%切换为>30%，或者反之亦然。
至少有两次 SCSA 分析的男性在 30 个月的时间内，DFI 的平均 CV 为 30.1%（SD 21.5）。与第一次测试相比，85%（95%置信区间：82-87%）的男性仍处于 30%截止点的同一侧。
尽管 DFI 个体内的 CV 较高，但 85%的不孕夫妇男性在两次测试之间并未改变类别，就 30%的截止值而言。因此，使用先前建立的 30%DFI 截止值，单次 SCSA 分析对评估体内生育能力具有较高的预测价值。
