Evaluation of an automated method for measuring von <scp>W</scp>illebrand factor activity in clinical samples without ristocetin
Bibliographic record
Abstract
INTRODUCTION: The development of an automated, von Willebrand factor (VWF) activity assay, Innovance(®) VWF Ac (VWF:Ac), which measures VWF binding to the platelet receptor glycoprotein Ibα without ristocetin, led us to evaluate the assay for diagnosing von Willebrand disease (VWD) and monitoring therapy. METHODS: After validating that the assay could be performed on an instrument from a different manufacturer, we compared VWF:Ac to VWF ristocetin cofactor activity (VWF:RCo) findings, including ratios of activity/antigen, for 100 healthy controls and 262 consecutive clinical samples from 217 patients (197 adults, 64 children, n = 1 age unknown) referred for VWF testing. RESULTS: There was excellent correlation (R(2) = 0.96) between VWF:Ac results run at two different sites on two different instruments. VWF:Ac had greater precision and sensitivity to low levels of VWF than the VWF:RCo method. Although there was good correlation between VWF:Ac and VWF:RCo results among healthy controls and patient subjects, VWF:Ac results were undetectable and/or significantly lower than VWF:RCo among patients who had types 2A, 2B, or 2M VWD. Additionally, a higher proportion of patient samples were classified as showing qualitative defects using the VWF:Ac compared with VWF:RCo method. While most samples drawn on VWD therapy had similar VWF levels by VWF:Ac and VWF:RCo, a type 2B VWD subject on replacement had much lower activity estimated by VWF:Ac. CONCLUSION: We conclude that Innovance(®) VWF Ac is suitable for the diagnosis, classification, and monitoring of VWD, and that it has a number of advantages over VWF:RCo method.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".