Diagnóstico da doença de von Willebrand: comparação entre metodologia semi-automatizada (VWF:RCo) versus automatizada (VWF:GPIbM).

Abstract

The measurement of von Willebrand Factor (VWF) activity has been a major challenge, impacting the correct classification of von Willebrand Disease (vWD) and, consequently, its management and treatment. The new 2021 ISTH guidelines for the diagnosis of vWD recommend the use of newer (automated) assays to measure VWF activity, replacing the semi-automated Ristocetin Cofactor (VWF:RCo) assay. In this context, the fully automated INNOVANCE VWF Ac kit emerges, with the potential for innovation and adaptation to the new recommendations and requirements imposed for the investigation and monitoring of patients with vWD. Therefore, the objective of this study was to compare the analytical performance of the INNOVANCE VWF Ac kit (automated method) with that of VWF:RCo (semiautomated method). A total of 104 plasma samples from patients with vWD were used, in addition to 20 samples from eligible blood donors (controls) from the Hemominas Foundation, Brazil. Participant data, including sex, age, race, and ABO blood group, were obtained. The methods used to measure VWF were VWF:RCo by aggregometry, INNOVANCE VWF Ac Kit, and von Willebrand Factor Antigen (VWF:Ag), both by turbidimetry. The study was approved by the Ethics Committee of the Hemominas Foundation. Spearman's correlation revealed a strong association between the INNOVANCE VWF Ac and VWF:RCo methods (r=0.944; p<0.05). The INNOVANCE VWF Ac and VWF:RCo methods demonstrated excellent analytical agreement (ICC = 0.953; 95% CI = 0.900–0.974). INNOVANCE VWF Ac showed a significantly higher median functional activity (71.15% vs. 64.00%; p < 0.0001) and an activity/VWF:Ag ratio close to 1, suggesting better correspondence with antigen concentration. INNOVANCE VWF Ac reproducibility was superior, with lower coefficients of variation in normal (1.94%) and pathological (4.67%) controls compared to VWF:RCo (9.54% and 12.66%, respectively). The results support the adoption of the INNOVANCE VWF Ac/VWF:Ag ratio cutoff point of 0.7, as it confers greater diagnostic specificity and reinforces the analytical superiority of the automated method. Therefore, replacing the conventionally used method by a modern and automated system is justified.