Abstract:The VWF multimer assay by Sebia is easy to perform and can be successfully implemented in any clinical laboratory for second-stage evaluation of VWD. The resolution power of multimer distribution is adequate to correctly classify VWD types 1, 2A, 2B, and 3.
“…On the other hand, Bowyer et al 17 and a recent report by Favaloro et al 39 published quantitative HMWM loss in some of the type 2M patients. However, Crist et al 18 and Pikta et al 19 do not mention type 2M VWD in their studies about H5/11VWM.…”
Background
Phenotypic von Willebrand disease (VWD) classification requires multiple tests including analysis of multimeric distributions von Willebrand factor (VWF) and evaluation of its structure. VWF multimer analysis is labor intensive, nonstandardized, and limited to specialized laboratories. A commercial semiautomatic assay, HYDRAGEL VW multimer assay (H5/11VWM, Sebia), has become available.
Objectives
Establishment of reference ranges for H5/11VWM to improve VWD classification.
Methods
Implementation validation, establishment and validation of normal and pathological reference intervals (NRIs/PRIs), comparison with in‐house method using 40 healthy volunteers and 231 VWD patients.
Results
Qualitative and quantitative validation of NRI obtained sensitivity of 88% and 79%, respectively, for type 2. Comparison of the two methods showed an overall concordance of 86% with major conflicting results in all atypical 2B (n = 7) and 50% 2M‐GPIb (n = 41) showing quantitative and qualitative multimeric loss, that was not detected with in‐house method. We were able to use established PRIs, with 73% validity in type 2 cases, to distinguish individual type 2A subtypes (IIA, IIC, IID, IIE) from 2M and 2B.
Conclusion
H5/11VWM could be used for all clinical purposes because its reliability and its rapid and accurate diagnostic ability and reduced observer bias. Although H5/11VWM cannot evaluate triplet structures, we were able to define 2A subtypes by stripping back to the percentage of intermediate/high‐molecular‐weight multimers. H5/11HWM could be an efficient and widely available alternative for the “gold standard” technique.
“…On the other hand, Bowyer et al 17 and a recent report by Favaloro et al 39 published quantitative HMWM loss in some of the type 2M patients. However, Crist et al 18 and Pikta et al 19 do not mention type 2M VWD in their studies about H5/11VWM.…”
Background
Phenotypic von Willebrand disease (VWD) classification requires multiple tests including analysis of multimeric distributions von Willebrand factor (VWF) and evaluation of its structure. VWF multimer analysis is labor intensive, nonstandardized, and limited to specialized laboratories. A commercial semiautomatic assay, HYDRAGEL VW multimer assay (H5/11VWM, Sebia), has become available.
Objectives
Establishment of reference ranges for H5/11VWM to improve VWD classification.
Methods
Implementation validation, establishment and validation of normal and pathological reference intervals (NRIs/PRIs), comparison with in‐house method using 40 healthy volunteers and 231 VWD patients.
Results
Qualitative and quantitative validation of NRI obtained sensitivity of 88% and 79%, respectively, for type 2. Comparison of the two methods showed an overall concordance of 86% with major conflicting results in all atypical 2B (n = 7) and 50% 2M‐GPIb (n = 41) showing quantitative and qualitative multimeric loss, that was not detected with in‐house method. We were able to use established PRIs, with 73% validity in type 2 cases, to distinguish individual type 2A subtypes (IIA, IIC, IID, IIE) from 2M and 2B.
Conclusion
H5/11VWM could be used for all clinical purposes because its reliability and its rapid and accurate diagnostic ability and reduced observer bias. Although H5/11VWM cannot evaluate triplet structures, we were able to define 2A subtypes by stripping back to the percentage of intermediate/high‐molecular‐weight multimers. H5/11HWM could be an efficient and widely available alternative for the “gold standard” technique.
“…We have previously reported on this multimer assay from the perspective of methodology validation, primarily via visual inspection of multimer patterns, but had not reported quantitative multimer separation vs quantitative VWF data. There have been few other reports on this method in the literature . Although some assessed multimer quantification according to manufacturer recommended groupings, none assessed this numerically in comparison with VWF activity/Ag ratios (as per our study), and none had assessed the chemiluminescence VWF procedures.…”
Introduction
Diagnosis of von Willebrand disease (VWD) is challenging due to heterogeneity of VWD and test limitations. Many von Willebrand factor (VWF) assays are utilized, including antigen (Ag), activity and multimer analysis. Activity assays include ristocetin cofactor using platelets (VWF:RCo) or other particles incorporating recombinant glycoprotein I (‘VWF:GPIbR’), or other GPI binding assays using gain‐of‐function mutations (‘VWF:GPIbM’), or collagen binding (VWF:CB).
Aim
To comparatively evaluate modern contemporary VWF activity assays vs VWF multimer analysis using modern contemporary methods.
Materials and methods
Several VWF activity assays (VWF:RCo, VWF:GPIbR, VWF:GPIbM, VWF:CB) assessed (typically as a ratio against VWF:Ag) against a new semi‐automated procedure for different types of VWD (1, 3, 2A, 2B, 2M), plus control material (n = 580). The evaluation also focussed on relative loss of high and very high molecular weight multimers (HMWM and VHMWM) by densitometric scanning.
Results
All evaluated VWF activity/Ag ratios showed high correlation to the presence/absence of HMWM and VHMWM, although VWF:CB/Ag and VWF:GPIbR/Ag ratios using an automated chemiluminescence method yielded highest correlation coefficients (r = .909 and .874, respectively, for HMWM). Use of the investigative procedure (VHMWM) identified fewer false positives for ‘loss’ in type 1 VWD.
Conclusions
This comparative investigation identified that new automated chemiluminescence VWF activity assays best identified relative loss or presence of HMWM and VHMWM according to activity to Ag ratios and an alternative investigative method for identifying VHMWM in multimer testing for a new commercial multimer method may lead to fewer false identifications of HMW loss in type 1 VWD.
“…4 Multimer profiles Historically, VWF multimer assays were complex, time-consuming, required specialised equipment and expertise, 10 and often evidenced poor performance in EQA. [18][19][20] More modern semi-automated assays are technically straightforward and reproducible [21][22][23][24]35 with the potential to also improve EQA performance; however, even these are not without limitations that may restrict contributions to diagnostics. The limitations of the Sebia methodology, as demonstrated here, are consistent with those described for the five-lane gel [21][22][23][24] and include lack of demonstrable triplet multimer patterns (due to single gel type provided; 2% agarose), poor discrimination of bands with VWF:Ag levels <20 U/dL, even when using manufacturer recommended adjusted sample dilutions, and limitations in comparative densitometry (maximum of two lanes), as well as restricted format of densitometry graphics ( Figure 1A-F).…”
Section: Discussionmentioning
confidence: 99%
“…Both offer same day qualitative assessment of size and distribution of VWF multimers, and several reports on the Hydragel-5 system have suggested this as an alternative to traditional in-house multimer methods and a useful screen in VWD diagnosis. [21][22][23][24] The main purpose of the current study was to validate the Hydragel-11 system, which to our knowledge has not yet been published. Nevertheless, we also generally report on further validation of the Hydragel-5.…”
Introduction: Accurate diagnosis of von Willebrand disease (VWD) enables effective patient management. von Willebrand factor (VWF) multimer analysis provides useful information regarding VWF multimer structure, thereby aiding VWD subtyping and management; however, historically technically challenging assays have had limited utility. This study evaluates the Sebia Hydrasys Hydragel-11 semi-automated VWF multimer assay and further validates the Hydragel-5 gel system, as primarily pertaining to VWD diagnostics and monitoring of therapy.
Methods: Provisionally diagnosed (via a reference assay test panel) archived patientsamples and prospective test patient samples, including those undergoing desmopressin trial or therapy monitoring, along with commercial and in-house control material and various external quality assessment (EQA) samples, were analysed. VWF multimers were evaluated for presence, loss or partial loss of high molecular weight (HMWM) and intermediate molecular weight (IMWM) multimers by both visual inspection and densitometric scanning, and comparison with reference assay results.
Results: All anticipated multimer patterns were reproduced, with patients generally showing multimer profiles matching expected patterns according to VWD type based on reference test panel 'diagnosis'. Occasional discrepancies were resolved by retesting. The increase in plasma VWF following desmopressin therapy was also clearly demonstrated. Multimer profiles of EQA samples complemented reference test panel results and matched EQA targets. There were some 'technical' limitations noted. Conclusion: This easy to use, standardised, semi-automated multimer analysis system can demonstrate the multimer profile of VWD patients, thus representing an additional laboratory tool for improved diagnosis, thereby facilitating appropriate patient management. K E Y W O R D S desmopressin, Hydragel, Multimers, von Willebrand disease, von Willebrand factor | 763 OLIVER Et aL.
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