Objective: To examine the factors associated with increased deoxyribonucleic acid fragmentation index (DFI), evaluate the pregnancy outcomes of men with increased DFI, and compare three independent DFI assays.
Design: Secondary analysis.
Setting: Nine US-based fertility centers.
Patients: Infertile men (N = 147) with sperm concentration ≤15 × 106/mL, motility ≤40%, or normal morphology ≤4% were enrolled. The female partners were ovulatory, ≤40 years old, and had documented tubal patency.
Interventions: At a baseline visit, the men provided a semen sample. The couples attempted conception without assistance for 3 months and with ovarian stimulation and intrauterine insemination in the subsequent 3 months.
Main outcome measures: The DFI was analyzed using the sperm chromatin structure assay (SCSA) with increased DFI defined as >30%. The predictors of increased DFI were determined by a multivariable linear regression model. The pregnancy outcomes were compared using the χ2 test. The independent DFI assays (SCSA, deoxynucleotidyl transferase-mediated dUTP nick end labeling, and Comet) were compared with Pearson and Spearman correlations.
Results: The 19% of men with increased DFI were older (36.0 vs. 33.0 years) and had lower total sperm motility (38.2% ± 20.5% vs. 45.2% ± 15.6%). Increased male age was found to be a significant predictor of DFI (0.75, 95% confidence interval [0.06, 1.45]). Increased DFI was not associated with conception or live birth. There was a modest correlation of the deoxynucleotidyl transferase-mediated dUTP nick end labeling assay with the SCSA (r = 0.34) and Comet assay (r = 0.19).
Conclusions: Older age was associated with increased DFI among infertile men. The DFI assays were only weakly correlated, indicating a standard definition of DFI is needed to truly interrogate how sperm deoxyribonucleic acid fragmentation impacts male fertility.
Keywords: DNA fragmentation indexes; DNA sperm fragmentation; male factor infertility.
© 2021 The Authors.