Table 2. Summary of intra-laboratory and inter-laboratory correlation coefficients (r), coefficient of variation (CV), and intra- and inter-observer variation (%) for SDF assays.
| Method | Intra-lab (r) | Intra-lab (CV) | Inter-lab (r) | Inter-lab (CV) | Intra-observer variation (%) | Inter-observer variation (%) | Study |
|---|---|---|---|---|---|---|---|
| TUNEL; benchtop flow cytometer | 0.75–0.956 | 0.1–5.7% | 0.83–0.937 | 0.2–5.2% | NR | NR | Ribeiro et al., 2017 |
| TUNEL; benchtop flow cytometer | NR | NR | NA | NA | ≤3%4 | ≤1.7%5 | Sharma et al., 2016 |
| TUNEL; standard flow cytometry | NR | NR | NA | NA | 3.2%2 | 4%3 | Sharma et al., 2010 |
| SCD* | 0.91 | NR | NA | NA | 1%9 | 0.21%10 | McEvoy et al., 2014 |
| SCD | NR | NR | NA | NA | 6–12%8 | 6–12%8 | Fernandez et al., 2005 |
| SCSA | NA | NA | 0.90 | ≤1% | NA | NA | Giwercman et al., 2003 |
| NR | 1.0–9.1%1 | NA | NA | NA | NA | Giwercman et al., 1999 |
*, Halosperm G2 test kit; 1, intra-assay CV varied between 1.0% and 9.1%, and the corresponding values for the inter-assay CV was 5.2% and 8.6%; 2, when absolute values were calculated, 80.0% of individual TUNEL measurement differed from the final designated values by no more than 3.2% (absolute difference); 57.1% of individual measurements in these data had a percentage difference less than 10% of the assigned value; 3, the absolute difference between an observer’s designated value and the mean among 2 observers was within 4.0% in 83.3% of specimens; in 83.3% of the specimens, the percentage difference between an individual observer’s designated TUNEL value and the 2 observers’ average value was within 15%; 4, a single TUNEL measurement from a given observer was within that observer’s average measurement by an absolute difference of 3% or less in 90% of cases; 5, the average TUNEL measurement from a given observer was within the two observers’ average measurements with an absolute difference of 1.73% or less in 80% of cases; 6, correlation between duplicate readings obtained in each laboratory (results from two participating laboratories); 7, correlation coefficient between two participating laboratories reading the same set of specimens; 8, coefficient of variation for the estimated percentage of spermatozoa with fragmented DNA; 9, the average difference in the values of SDF between the two replicates was 1.02%±0.55% (absolute variation); the average percentage difference between the two replicates for each sample was 4.16%; 10, the average difference in the values of SDF between two technicians for each sample was 0.21%±0.57% (absolute difference); the average percentage difference between the two technicians for each sample was 9.56%. SDF, sperm DNA fragmentation; TUNEL, terminal deoxyribonucleotide transferase-mediated dUTP nick-end labeling assay; SCD, sperm chromatin dispersion test; SCSA, sperm chromatin structure assay; NR, not reported; NA, not applicable; CV, coefficient of variation.