Summary of main findings through recent EQA exercises6,9
| Main finding . |
|---|
| The least variable platelet-dependent VWF activity assay (with the lowest quantification limit) was VWF:GPIbR performed by CLIA procedure on the ACL AcuStar instrument, followed by VWF:GPIbR performed by LIA, VWF:GPIbM (LIA), and VWF:RCo (Figure 1A) |
| CLIA was by far the least variable method overall, which was true for VWF:Ag, VWF:GPIbR, and VWF:CB, as compared with other comparative methodologies (Figure 1A) |
| In terms of associated diagnostic errors between identification of type 1 vs type 2A/B VWD samples, the most problematic platelet-dependent VWF activity assay was VWF:RCo (responsible for 26.7% of such errors), followed in order by VWF:GPIbM (22.2%) and VWF:GPIbR (LIA; 3.7%) |
| The least problematic VWF activity assay overall was VWF:CB (1.5% of errors), especially if performed by CLIA (no errors) |
| A standard 3-test panel, as recommended in the recent guidelines,1 was associated with a twofold error rate compared with a 4-test panel incorporating VWF:CB, as recommended by UK guidelines4 |
| No single universal cutoff value (eg, 0.5 or 0.7) for activity/Ag is sufficiently robust to effectively identify/exclude type 2 VWD, with cutoff values being somewhat method specific (Figure 1B); if a universal cutoff is required, perhaps 0.6, in line with the recommendations of the UK Haemophilia Doctors organization,4 could be favored (supplemental Figure 1) |
| The best type 1 vs 2A/2B discrimination was seen using CLIA methods (ie, GPIbR/Ag or CB/Ag), followed by GPIbR/Ag using LIA; other methods, including RCo/Ag and GPIbM/Ag, showed substantial overlap in ratios between type 1 vs 2A/2B VWD (Figure 1B) |
| The composite of these data favors CLIA methodology over all other methodologies; for the platelet-binding activity assays, VWF:GPIbR is favored over both VWF:GPIbM and VWF:RCo |
| Main finding . |
|---|
| The least variable platelet-dependent VWF activity assay (with the lowest quantification limit) was VWF:GPIbR performed by CLIA procedure on the ACL AcuStar instrument, followed by VWF:GPIbR performed by LIA, VWF:GPIbM (LIA), and VWF:RCo (Figure 1A) |
| CLIA was by far the least variable method overall, which was true for VWF:Ag, VWF:GPIbR, and VWF:CB, as compared with other comparative methodologies (Figure 1A) |
| In terms of associated diagnostic errors between identification of type 1 vs type 2A/B VWD samples, the most problematic platelet-dependent VWF activity assay was VWF:RCo (responsible for 26.7% of such errors), followed in order by VWF:GPIbM (22.2%) and VWF:GPIbR (LIA; 3.7%) |
| The least problematic VWF activity assay overall was VWF:CB (1.5% of errors), especially if performed by CLIA (no errors) |
| A standard 3-test panel, as recommended in the recent guidelines,1 was associated with a twofold error rate compared with a 4-test panel incorporating VWF:CB, as recommended by UK guidelines4 |
| No single universal cutoff value (eg, 0.5 or 0.7) for activity/Ag is sufficiently robust to effectively identify/exclude type 2 VWD, with cutoff values being somewhat method specific (Figure 1B); if a universal cutoff is required, perhaps 0.6, in line with the recommendations of the UK Haemophilia Doctors organization,4 could be favored (supplemental Figure 1) |
| The best type 1 vs 2A/2B discrimination was seen using CLIA methods (ie, GPIbR/Ag or CB/Ag), followed by GPIbR/Ag using LIA; other methods, including RCo/Ag and GPIbM/Ag, showed substantial overlap in ratios between type 1 vs 2A/2B VWD (Figure 1B) |
| The composite of these data favors CLIA methodology over all other methodologies; for the platelet-binding activity assays, VWF:GPIbR is favored over both VWF:GPIbM and VWF:RCo |
CLIA, chemiluminescence immunoassay; LIA, latex immunoassay.