Accurate diagnosis of von Willebrand disease (VWD) depends on the quality, precision, and variability of the laboratory assays. The North American Specialized Coagulation Laboratory Association (NASCOLA) is a provider of external quality assessment (EQA) for approximately 60 specialized coagulation laboratories in North America. In this report, NASCOLA EQA data from 2010 to 2021 are reviewed for trends in methodology and precision among various assays. In particular, recent ASH ISTH NHF WFH (American Society of Hematology, International Society on Thrombosis and Haemostasis, National Hemophilia Foundation, and World Hemophilia Federation) guidelines for diagnosis of VWD are reviewed in light of EQA data. In contrast to other geographic regions, laboratories in North America predominantly use three-assay screening panels (antigen, platelet-binding activity, and factor VIII [FVIII] activity) rather than four-assay panels (antigen, platelet-binding activity, FVIII activity, and collagen-binding activity). They also use latex immunoassays rather than chemiluminescence immunoassays, and the classic ristocetin cofactor (VWF:RCo) assay and monoclonal antibody (VWF:Ab) assay to assess VWF platelet-binding activity over newer recommended assays (VWF:GPIbM and VWF:GPIbR). Factors that may be influencing these North American practice patterns include lack of Food and Drug Administration approval of the VWF:GPIbM, VWF:GPIbR, collagen binding assays, and chemiluminescence methodologies, and the influence of the 2008 National Heart, Lung, and Blood Institute guidelines on laboratory practice. Lastly, systems-based solutions are urgently needed to improve the overall accuracy of laboratory testing for VWD by minimizing preanalytical variables and adopting assay standardization.
Background Laboratory diagnosis of von Willebrand Disease (VWD) is complex. Reliance on laboratory testing can be problematic as different VWD screening panels, assays and methodologies can produce analytic variability in test results. Objectives To compare the degree of imprecision among the VWD assays and within the platelet binding activity (PBA) assays, to determine the consensus among the VWD assays for correct classification of sample results, and to determine consensus among laboratories’ von Willebrand factor (VWF) multimer interpretations and final interpretations of the VWD panels. Patients/Methods Proficiency testing results from the North American Specialized Coagulation Laboratory Association (NASCOLA) submitted by laboratories from 2010 to 2019 for all normal, type (T) 1 VWD and T2 VWD samples were analysed. Results and Conclusions Imprecision was lowest for VWF antigen and highest for collagen binding activity (CBA) with median coefficient of variation (CV) of 12% (interquartile range (IQR) 7%) and 23% (IQR 21%) respectively. Within the VWF PBA assays, the gain‐of‐function mutant GP1b binding (VWF: GP1bM) methods had the least imprecision (CV 9%, IQR 10%). All assays, including the various PBA methods had excellent consensus. The majority of laboratories agreed that normal (median consensus‐82%, IQR 16%) and T1 VWD (median consensus‐100%, IQR 9%) samples had normal multimer distribution. Consensus among laboratories for final interpretations was excellent for normal samples (median 81%, IQR 8%), good for T1 VWD samples (median 59%, IQR 9%), and fair for T2 VWD samples (median 44%, IQR 21%). Consensus on final interpretation decreased as sample complexity increased.
Background Iron deficiency (ID) is the most common and widespread nutritional deficiency in both developing and developed countries (Mei et al., 2011; World Health Organization, 2001). Women of childbearing potential are at highest risk of ID due to regular menstrual losses as well as the increased iron demands of pregnancy and lactation (Lynch, 2011; McMahon, 2010). During pregnancy, the risk for ID and iron deficiency anemia (IDA) increases due to the additional iron requirements to support expansion of blood volume/red cell mass and growth of the fetus and placenta (McMahon, 2010; Mei et al., 2011). Common symptoms of ID with or without anemia during pregnancy include fatigue, shortness of breath, difficulty concentrating, higher rates of preterm delivery, and red blood cell transfusions (World Health Organization, 2001). Poor prenatal iron status is also associated with diminished cognitive performance, language ability, and motor functions in the child (Tamura et al., 2002). Despite international recommendations and guidelines on the screening and management of ID in pregnancy, it remains a problem of epidemic proportions and is often left unrecognized and untreated. To increase recognition and appropriate management of ID and IDA in pregnancy, we developed and implemented a quality improvement project, the IRON Deficiency project in Pregnancy: Maternal Iron Optimization (IRON MOM). This project was implemented January 1st, 2017 at St. Michael's Hospital (SMH), an inner-city tertiary centre in Toronto, Canada. The IRON MOM included educational resources for clinicians and patients, standardized oral iron prescriptions, modified lab requisitions, and clinical pathways to guide the screening, diagnosis and management of ID for obstetricians. Objective The primary objective of this study was to assess the prevalence of ID and IDA in unselectively screened pregnant women after the implementation of the IRON MOM quality improvement project. Methods We performed a retrospective audit of administrative laboratory data collected from all obstetrical clinics between January 1 and December 31, 2017. ID was defined as a serum ferritin <50μg/L (Guyatt et al., 1992) . IDA was defined as a dual diagnosis of ID and anemia based on hemoglobin levels <110 g/L and ferritin levels <50μg/L. Descriptive statistics were used to calculate frequencies and proportions. SAS version 9.4 was used to perform the analyses. Results A total of 1830 pregnant women were screened for ID during their obstetrical visit. Of the 1830 pregnant women, 1307 had one ferritin test and 523 pregnant women had two or more tests. A total of 91.3% (1193/1307) of pregnant women were iron deficient (ferritin <50μg/L) where 31.5% (411/1307) had ferritin levels between 15-29μg/L, and 49.4% (645/1307) had severe ID (ferritin <15μg/L). For the women who had two or more ferritin tests, 78.6% (411/ 523) were iron deficient at the first visit which then increased to 96.2% (503/523) by their second visit. When ferritin and hemoglobin values were linked and measured on the same day, 25.9% (346/1336) of pregnant women had IDA over the course of their outpatient care. Conclusion After the implementation of the IRON MOM, we found an extremely high prevalence of ID in our pregnant patient population in the outpatient setting. This confirms that ID remains an underappreciated problem, even at a tertiary care centre. Our findings highlight a tremendous gap in awareness, which demands strategies to improve knowledge translation. Future directions include the simplification and digitization of IRON MOM to empower pregnant women to advocate for their care. Disclosures Sholzberg: Novartis: Honoraria; Amgen: Honoraria, Research Funding.
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