Pruthi, Rajiv K.

Abstract Introduction Type 1 von Willebrand disease (VWD 1) accounts for ~75% of VWD. The National Heart, Lung, and Blood (NHLBI) VWD guidelines recommend VWF:Ag and VWF:RCo cut-off levels of <30 (IU/dL or %) for definite laboratory diagnosis of VWD 1. However, guidelines indicate that patients with "low VWF" (VWF:Ag and VWF:RCo in the 30-50 IU/dl range) could be candidates for agents to increase VWF levels if they are at risk for bleeding. Here we examine the diagnostic practices for VWD at Mayo Clinic Rochester by determining the proportion of patient currently classified as VWD 1 that meet NHLBI criteria for "low VWF". In addition, we assess changes in the laboratory phenotype of the aging population of patients with "low VWF" and VWD 1. Methods Patients with a diagnosis of VWD 1 at our institution were identified through our institutional hemophilia treatment center database (1986 to 2017). All available VWF:Ag and VWF activity (ristocetin cofactor assay [VWF:RCo] and latex immuno-activity assay [VWF:Ab]) levels performed at our institution and available in our electronic medical record (EMR) were recorded. Exclusion criteria included confounding variables known to effect VWF levels (eg,. hormonal therapy, pregnancy, desmopressin, or VWF/VIII concentrate administration) at the time of first laboratory assessment (VWF:Ag and VWF activity (by either VWF:Ab or VWF: RCo) at our institution. Bleeding score, retrospectively assessed using the MCMDM-1 VWD bleeding assessment tool (BAT), at the time of first clinical evaluation was recorded if enough information was available in the EMR. All VWF testing was recorded for comparative analysis between the first and the most recent measurements within the study period. Patients were not included in age-related analysis if the most recent laboratory values were obtained in the presence of the confounding variables noted above. Statistical analysis was performed using JMPfor paired t-tests and STATA for multilevel mixed-effects regression analysis. Results 78 patients (50 F) met study criteria. Median age at initial presentation at our institution was 27.5 (0-75) years. Medians (ranges) for VWF:Ag (n=78), VWF:Ab (n=41), and VWF:RCo (n=75) were 39 (5-60)%, 37 (19-53)%, and 36 (11-62)%, respectively (reference ranges 55-200% for VWF and factor VIII values). Coagulation factor VIII activity (FVIII:C) was 63 (10-122)% (n=78). Of 37 patient with available blood type results, 23 (62%) were blood group O. 56% of patients (n=44) met NHLBI criteria for classification as "low VWF" (Figure 1, Panel A). There was no difference in bleeding score between patients with VWD 1 (median bleeding score: 4 (0-14), n=22) compared to those with "low VWF" (median bleeding score: 4 (0-14), n=37). 54 patients had repeat laboratory testing at 4.5 (0-29) years after initial testing. VWF antigen and activity levels were compared in those who had repeat testing done >1 year (n=36) after initial lab testing at our institution. Median age of patients at time of most recent measurement was 42.5 (5-87) years compared to 35.5 (0-75) years at first measurement. VWF:Ag was significantly higher in the most recent measurement compared to the first measurement (p< 0.05, Figure 1, Panel B ). There was no statistically significant difference between VWF activity levels in the first versus the most recent measurement. There was a non-significant trend towards increasing VWF:Ag with increasing age; however when stratified into "low VWF" and VWD 1 disease groups, there was a significant relationship between VWF Ag and age in the "low VWF" group with mixed effects regression model (coefficient: 0.207, p:0.043). Conclusion Approximately 55% of patients with a clinical diagnosis for VWD 1 meet criteria for "low VWF." In our cohort, there was no difference in bleeding (BAT) scores between the two groups; however our analysis is limited by its retrospective nature. We also demonstrate a statistically significant increase in VWF:Ag with aging; however, with regression analysis, this change was only noted in those in the "low VWF" group. Larger prospective studies controlling for confounding factors are needed to further demonstrate the effect of age on VWF antigen and activity levels. Disclosures No relevant conflicts of interest to declare.

Abstract Background An increasing number of patients (pts) requiring anticoagulation are treated with oral factor Xa inhibitors (DOAC) as an alternative to vitamin K antagonists. Prior to the recent approval of coagulation factor Xa (recombinant), inactivated-zhzo in May 2018, four factor prothrombin complex concentrates (4PCC) have been used to reverse the effects of DOACs. We retrospectively analyzed our institutional experience with 4 PCC for reversal of apixaban and rivaroxaban to determine the indications for 4PCC use and outcomes. Methods After IRB approval, pts receiving 4PCC, from Feb 2016 to January 2018 were identified from our pharmacy database and pts receiving PCC for reversal of apixiban and rivaroxaban were selected. Consenting pts medical records (MR) were reviewed for demographics and indications for DOAC and 4PCC as well as outcomes of 4PCC use. Pts were excluded if they had discontinued DOAC greater than 7 days before receiving 4PCC or if they were started on alternative forms of anticoagulation at a therapeutic dose prior to receiving PCC. Primary endpoint was clinical efficacy (clinical improvement or stability) or ability to undergo required procedure) and secondary endpoint was safety (thromboembolism and death) up to 35 days post-infusion of 4PCC. Stability for intracranial hemorrhages (ICH) was determined by clinical improvement and if head imaging performed, no change in head CT or MRI scan, whereas stability for other bleeds was determined by hemoglobin stability and opinions of providers in the MR. Primary efficacy outcome for pts undergoing surgery was based on MR comments by the performing surgeon and use of other hemostatic agents and red blood cell transfusions. Results 49 (32 male) pts, median age of 74 (31-95) years, met our study criteria and received 4PCC for reversal of apixaban (n=29) and rivaroxaban (n=20). Indications for anticoagulation were atrial fibrillation (n=35) and thrombosis (n=14). Of the 14 pts with thrombosis, 11 had deep vein thrombosis while 3 had thrombosis at other sites (arterial graft thrombus, aortic thrombus, and portal vein thrombosis). 4PCC was administered in the emergency department (n=36), intensive care unit (n=10), or the general medical wards (n=3). Indications for 4PCC included bleeding (n=40), procedure/surgery (n=6), and hemodynamic instability with clinical suspicion for bleeding (n=3). Bleeding location is reported in table 1. All procedure/surgery performed for clinical symptoms not related to hemorrhage were non-elective procedures and included exploratory laparotomy (n=4), laparoscopic cholecystectomy (n=1), and incision and drainage of abdominal wall abscess (n=1). Median PCC dose was 42 (10.3-63.3) IU/kg. Outcomes 32/40 (80%) pts had stability or an improvement in bleeding, while 5 pts had bleeding that did not improve. 3 pts, all with ICH, had a bleed that worsened 8 (6-8) hours after PCC but then spontaneously stabilized 24 (8-24) hours later. Of those presenting with clinical bleeding, 3 pts received FFP within 3 hours prior to treatment with 4PCC, 2 pts received FFP within 12 hours after 4PCC, and 2 pts received FFP within 3 hours before and 12 hours after 4PCC. Of 40 pts receiving PCC for bleeding, 14 also had a procedure to help achieve hemostasis (Table 2). All 6 pts were able to undergo procedure/surgery. 5/6 patients achieved adequate hemostasis. One pt had no mention of unanticipated bleeding in the MR but received 8 units of FFP intraoperatively after 4PCC. 6/49 (12%) pts had a thrombotic complication within 35 days of receiving PCC (median 4 days; (range 1-31) including arterial graft thrombus (n=1), superficial venous thrombus (n=1), bilateral soleal vein thrombosis (n=1), internal jugular vein and innominate vein thrombosis (n=1) stroke (n=1), and progression of preexisting portal vein thrombosis (n=1). All-cause mortality was 20%. 3/10 deaths were in pts who never achieved neurologic recovery after ICH and one pt had stroke-like symptoms leading to death 30 days after 4PCC (administered for ICH). Conclusion In this cohort, 80% of pts demonstrated clinical stability/improvement of hemorrhage. All pts were able to undergo surgical procedures; however 17% required additional FFP to achieve hemostasis. Thromboembolism occurred in 12% of patients. No deaths could definitely be attributed to 4PCC; however, 30% of deaths could be attributable to the underlying hemorrhagic episode. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Gastric cancer is one of the most pro-thrombotic tumor types, and after accounting for prevalence, it may be responsible for a significant burden of cancer-associated venous thromboembolism (VTE). Patients with gastric cancer are also at high risk for gastrointestinal bleeds (GIB), making primary thromboprophylaxis and anticoagulation an ongoing treatment challenge. Due to these competing risks, patients with gastric cancer may not be eligible for clinical trials of thromboprophylaxis and treatment of cancer-associated VTE. Additional information regarding the severity and outcomes of both gastrointestinal hemorrhage and VTE in patients with gastric cancer would be useful to guide clinical decision-making. Aim: To determine the annual rates, inpatient mortality, length of stay and cost of VTE- and GIB-related admissions in patients with gastric cancer. Methods: We queried the 2009-2014 Nationwide Inpatient Sample (NIS) database, a nationally weighted hospital admissions database developed for the Healthcare Cost and Utilization Project, to identify adults (age ≥ 18 years) hospitalized with gastric cancer. Hospitalizations in which VTE or GIB were among the top-five discharge diagnoses, were considered an admission complicated by one of these events. In-hospital outcomes of patients with VTE were compared to those with GIB. We used linear regression models to analyze trends in outcomes over time and binary logistic regression with forward modeling to identify predictors of inpatient mortality. All statistical analyses were conducted with SPSS, version 24 (IBM, Armonk, NY). Results: Among a total of 253,680 admissions with gastric cancer, 17,831 (6.7%) experienced a GIB whereas 10,992(4.2%) had VTE. Of those patients who experienced VTE, the majority (49.7%) developed pulmonary embolism, followed by lower extremity deep vein thrombosis (41.8%) and upper extremity deep vein thrombosis (8.54%). The patients included in this study were mainly white (53.7%) men (63.6%) with a median age of 67 (IQR:20) years; and a mean of 6 (SD: 2.83) chronic medical conditions. The annual GI bleed rate remained stable during the study period (16% in 2009 to 17.2% in 2014: p = 0.67) with a significant downtrend in inpatient mortality (18.8% in 2009 to 13.7% in 2014: p <0.01). In contrast, the annual rates of VTE-related admissions showed a small but significant uptrend (15% in 2009 to 18.1% in 2014: p <0.01) and an uptrend in the inpatient mortality during the study period (15.7% in 2009 to 19.2% in 2014: p <0.01). The overall inpatient mortality was higher among patients with VTE than with GI bleeds (10.2% vs 6.5%, p < 0.01; OR univariate: 1.51, CI: 1.42 - 1.61, p < 0.01). The negative effect of VTE on inpatient mortality persisted after adjusting for possible confounders such as metastatic disease, several comorbidities and demographics (OR: 1.39, CI: 1.30 - 1.49, p < 0.01). The VTE-associated admissions had a slightly longer length of stay (median, 6 vs 4 days, p < 0.01) with a significantly higher cost compared to GI bleed ($45,599 vs $31,219, respectively, p < 0.01). Conclusion: In this NIS cohort of hospitalized patients with gastric cancer, GIB was more frequently observed than VTE, but those with VTE had higher inpatient mortality, longer length of stay, and higher hospital costs. Clinicians should be aware of patient-specific risk factors for both VTE and GI bleed and take these factors into account when discussing VTE prophylaxis and treatment with patients. Future studies should look to identify those patients with gastric cancer who would benefit most from primary VTE prophylaxis as well as identify ideal agents for the treatment of gastric cancer-associated VTE. Figure. Figure. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction Heparin induced thrombocytopenia (HIT) is often not considered as a potential etiology of thrombocytopenia. The gradual 5 to 14 day decline in platelet count (PC) may not be easily recognized by busy clinicians. The life-threatening complications of HIT are potentially preventable with prompt recognition and management. Implementation of computer-based clinical decision support systems (CDSS) may aid in addressing these issues. Such systems have shown promise in increasing provider recognition, appropriate testing, and management of a variety of conditions. Methods We developed, implemented and evaluated a CDSS designed to identify patients at risk for HIT. The CDSS was integrated into the electronic medical record (Centricity Enterprise, GE) at Mayo Clinic Rochester. The CDSS identified inpatients with recent or active use of heparin medications, who experienced a 50% PC drop. For such patients, the system generated an electronic message alerting their care team of the 50% PC drop and asked them to consider the possibility of HIT. A link to a website with recommendations for the diagnosis and management of HIT was included with the alert. Providers were encouraged to assess for HIT using the 4Ts Score and, if indicated, the anti-heparin/platelet factor 4 (PF4) antibody assay. We performed a retrospective chart review of consecutive patients identified by the system and equal number of randomly generated controls that did not trigger alerts. The accuracy of the algorithm was assessed and errors were analyzed for clinical significance. Patient risk of HIT was evaluated by using the 4Ts Score and the HIT Expert Probability (HEP) Score. Alert effect was classified as: Results Over the study period, 2,785 patients had a total of 37,060 PC (13.31 PC/patient) and the CDSS triggered a total of 124 alerts. About 10% of alerted clinicians reviewed the website with recommendations on the management of HIT. A total of 117 patients generating alerts were compared to 124 controls. Demographics between the two groups were similar. The CDSS had a 95% sensitivity for accurately detecting a 50% platelet drop for inpatients on heparin. The specificity was 74%. The Objective alert effect was found in 21% of the cases (16% of providers changed their management and 5% documented that HIT was felt to be unlikely). The most common actions taken after receiving the alert were obtaining a HIT antibody assay, withholding heparin, consulting a subspecialty service, and/or changing anticoagulants. The Probable alert effect was 14% of the cases. HIT had been considered before the alert was sent in 11% of patients. Alert effect was classified as None for the remaining 54% of patients. Anti-heparin/PF4 testing for HIT was ordered for 25% of the intervention patients compared to 3% of controls. For the intervention group, PF4 was negative for 86% of tested patients, equivocal for 10%, and positive in 3%. All PF4 tests were negative in the control group. 4Ts score was greater than or equal to 4 in 38% of patients and averaged 3.1 (range 7 to 0). HEP score averaged 4 (range 14 to -4). Risk calculations showed a trend to higher risk with therapeutic heparin compared to prophylactic heparin preparations. HIT risk scores were comparable by admitting service and diagnosis. Conclusions Our CDSS successfully identified upwards of 95% of inpatients at risk for HIT. However, approximately 26% of the alerts were false positives. Only a small proportion of clinicians accessed the website with recommendations for the diagnosis and management of HIT but patients with a suspected HIT were managed appropriately. Of the patients triggering a HIT alert, 38% had an intermediate or high clinical probability of HIT based on the 4Ts Score that would be an indication for further testing. This result highlights the success of the CDSS in identifying patients needing further evaluation but also the difficulties of a computer-based CDSS in representing all the important clinical criteria for the diagnosis of HIT. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction: Differences in coagulation assay reagents may lead to variable results for some extended-half-life (EHL) recombinant factor VIII (rFVIII) products, with the potential to adversely affect patient care. Laboratories assessing EHL-rFVIII activity can choose from many available one-stage assay and chromogenic assay reagents. A field study was conducted to evaluate the ability of clinical laboratories to accurately measure FVIII activity in plasma samples spiked with BAY 94-9027, an EHL rFVIII, when using diverse assay reagents and when guided in the choice of reagent. In a regional subanalysis, BAY 94-9027 field study results from clinical laboratories in the United States and Canada were compared with those from Europe and Israel. Methods: In this 2-part study, a broad range of laboratories in the United States, Canada, Europe (Austria, Germany, Italy, Romania, Spain, Switzerland, United Kingdom), and Israel were provided samples containing defined concentrations of BAY 94-9027 or an unmodified rFVIII (antihemophilic factor [recombinant] plasma/albumin-free method [rAHF-PFM]) as a control. In part 1, each laboratory measured FVIII activity using their routine methods (one-stage assay, chromogenic assay, or both); laboratories that had ≥2 routine one-stage assays were asked to perform sample testing with one of the less commonly used assays in the laboratory to ensure that part 1 captured both the prevalence and heterogeneity of one-stage assays used in the geographic regions studied. In part 2, laboratories used one-stage assays with SynthASil and Pathromtin SL reagents provided by Bayer; SynthASil and Pathromtin SL have previously been shown to accurately measure BAY 94-9027 and full-length rFVIII products. The field study data were analyzed to identify the most commonly used reagents in the 2 regions (United States/Canada and Europe/Israel) and to assess if regional differences resulted in differences in accuracy of FVIII activity measurement. Results: 52 laboratories (US/Canada, n=25; Europe/Israel, n=27) participated in the field study. The one-stage reagent SynthASil was commonly used in all countries (n=15) in part 1, but differences were seen in the frequency of use of other reagents. PTT-A (n=6) and Actin FSL (n=5) were frequently used in the US/Canada and Actin FS (n=6) and Pathromtin SL (n=6) in Europe/Israel. Regional differences in the choice of assay, with US/Canada more likely to use assays that did not accurately measure BAY 94-9027, affected the ability of laboratories to accurately measure FVIII activity in the spiked samples (Figure). In part 1 of the study, regional differences in median recovery of BAY 94-9027 were seen among laboratories when using their own in-house one-stage assays. These differences were not seen in part 2 of the study when laboratories used provided reagents (SynthASil and Pathromtin SL), despite using the same instrumentation as used in part 1. Regional differences in part 1 might have been exacerbated by use of less common, and potentially inappropriate, one-stage assay reagents, affecting the accuracy of BAY 94-9027 measurement. Chromogenic assay use was more common in Europe/Israel (n=11) than US/Canada (n=5). No regional differences in chromogenic assay results were observed. Conclusions: Most clinical laboratories were able to accurately measure BAY 94-9027 activity using their in-house assays. However, regional differences in the accurate measurement of BAY 94-9027 activity were influenced by regional choice of one-stage reagents used in part 1 of the study; the activity and accuracy differences were eliminated when all laboratories used the same provided one-stage reagents with their in-house instruments (part 2 of study). Therefore, standardization of laboratory procedures and use of newer, more accurate one-stage assay reagents should improve measurement of FVIII activity with EHL products. Figure. Figure. Disclosures Castellone: Bayer: Membership on an entity's Board of Directors or advisory committees; Wilmer-Hale: Consultancy. Church:Bayer: Employment. Leong:Bayer: Employment. Kitchen:Bayer: Consultancy, Other: travel reimbursement, Speakers Bureau.

Abstract Background: Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are screening tests of hemostasis commonly ordered for anticoagulant therapy monitoring, evaluation of bleeding, screening for acquired or inherited deficiencies of coagulation factors, and preoperative screening. Evaluation of a prolonged PT/aPTT is best accomplished in an algorithmic fashion consisting of mixing studies and factors assays or inhibitor testing as indicated. However, there is little data available on frequency of conditions that may result in abnormalities of PT/aPTT. The Special Coagulation Laboratory (SCL) at our institution offers an algorithmic approach termed Prolonged PT/aPTT Profile (PT/aPTT profile). Aim: To review our institutional experience with PT/aPTT profile testing (indications and outcomes), and to provide clinical correlation of abnormal PT/aPTT tests on patients seen at our institution in an effort to explain common causes of altered hemostatic testing in outpatient clinical practice. Methods: In this retrospective study, following IRB approval, we reviewed the medical records of patients who underwent outpatient PT/aPTT profile testing in the SCL at Mayo Clinic in Rochester, Minnesota between 2010 and 2017. Data abstracted included patient demographics and clinical presentation, indications for testing, use of anticoagulants, medical diagnoses which could potentially influence coagulation, and results of hemostatic testing (Table 1). Statistical analyses were completed using SAS 9.4 (SAS Institute Inc., Cary, North Carolina). Continuous variables are presented as median (range) while discrete variables are summarized as frequency (percentage). Comparisons of clinical characteristics between groups are made using the rank-sum test for continuous variables. Statistical significance is defined as a 2-tailed P value of less than 0.05. Results: A total of 107 patients met our study criteria, 58 (54 %) male, median age 55 years (range 1-89). Indications for testing included prior prolongation of PT (48%), PTT (29%), PT and aPTT (8%) on outside coagulation testing performed in a non-SCL setting, clinical bleeding episodes (10%) and preoperative screening (5%). Patients with established medical diagnoses known to influence coagulation testing including solid tumors, hematologic malignancies, liver disease, renal disease, autoimmune and rheumatologic conditions and pregnancy were documented along with other baseline patient characteristics (Table 1). SCL PT/aPTT profile testing revealed normal results in 29 of 107 (27%) patients on repeat testing while 78 patients warranted further evaluation of which 27 (35%) had an isolated prolonged PT, 28 (36%) had a prolonged APTT and 23 (29%) had prolongations of both PT and aPTT. After further workup and clinical correlation, causes of abnormal outpatient PT/aPTT profile testing were found to be related to an underlying congenital condition in 16 (21%) patients - most commonly factor VII deficiency (9%) and factor VIII deficiency (4%) - acquired conditions in 53 (68%) patients - most commonly anticoagulant therapy effects (31%) and liver disease (21%) - and of unclear etiology in 7 (9%) cases (Table 2). Specifically, the most common cause of an isolated prolonged PT in our study was found to be vitamin K deficiency (37%) whereas elevations in aPTT and both PT/aPTT were most frequently attributed to the effects of anticoagulant therapy (29% and 52% respectively). Other causes of prolongation on PT/aPTT profile testing following clinical correlation were also identified (Table 2). Discussion: While PT and aPTT are commonly ordered tests, there is little evidence regarding epidemiology of testing indications, distribution of test results, and the clinical correlation of test results. Our study demonstrates that abnormalities in hemostatic testing can be attributed to a wide range of causes including artefactual prolongation influenced by pretest variables or marked abnormalities in secondary hemostasis due to inherited and acquired conditions. Strengths of this study include the SCL algorithmic approach to testing to further elucidate coagulation cascade abnormalities to properly characterize conditions that pose severe hemostatic risk while limitations of this study reflect the experience of a single institution and possible referral bias. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction Varied presentations of vitamin B12 (B12) deficiency include hematologic (megaloblastic anemia) and neurologic (myelopathy, peripheral neuropathy). Delayed recognition and treatment may have serious consequences. Assessing B12 status can be challenging due to diverse laboratory assays and thresholds, resulting in a wide range of reported prevalence of B12 deficiency from 3-26%. Comorbidities may also spuriously elevate or suppress B12 levels. Methylmalonic acid (MMA) level, often used as a companion test to assess for B12 deficiency, may also be affected by differing laboratory thresholds and other medical comorbidities, such as renal dysfunction. Our institutional approach to B12 assessment, termed the pernicious anemia (PA) cascade, consists of reflexive testing to 1) document low B12 stores (B12 levels with or without MMA), and 2) diagnose pernicious anemia (intrinsic factor binding antibody [IFBA] with or without gastrin assay). In this study, our objectives were: (1) assess the usefulness of our B12 testing algorithm and associated laboratory thresholds for identifying B12 deficiency, and (2) evaluate clinical follow-up of test results as part of a quality project. Methods In this retrospective study, adult (age ≥18 years) inpatients who had B12 testing from 2007 to 2013 were identified. Medical records for those patients with B12 levels 150-400 ng/L were reviewed. Data abstracted included patient demographics, indication for B12 testing, B12 levels, results for MMA, IFBA, gastrin, serum creatinine, complete blood count, and clinical outpatient follow-up. The PA cascade algorithm is as follows: 1) for B12 <150 ng/L, IFBA is performed; 2) if IFBA is negative or indeterminate, then gastrin is performed; 3) for B12 150-400 ng/L, MMA is performed; 4) if MMA is >0.40 nmol/mL, then IFBA is performed. Reference range for B12 is 180-914 ng/L. Patients were determined to be B12 deficient if B12 level was <180 ng/L, or if B12 was 150-400 ng/L with elevated MMA and macrocytosis in the absence of significant renal dysfunction, defined as serum creatinine ≥2.0 mg/dL. Results Records of 326 patients (150 female) were reviewed. Indications for B12 testing were: hematologic, 175 patients (53.7%); neurologic, 127 patients (39.0 %), psychiatric, 18 patients (5.5%); other, 4 patients (1.2%). Fifty-nine of 326 (18.1%) patients were B12 deficient, of whom 17 of 59 (28.8%) had PA. There were 54 cases of elevated MMA, >0.40 nmol/mL, of which 30 cases had mildly elevated MMA, >0.40 nmol/mL and ≤0.60 nmol/mL, considered to be the MMA "gray zone". Thirty-two of the total 326 patients had serum creatinine ≥2.0 mg/dL, of which 23 patients also had elevated MMA. Elevated MMA in 13 of these 23 patients was more likely due to renal dysfunction than to B12 deficiency. B12 testing results were not mentioned in hospital discharge summaries for 173 patients, including 8 patients with B12 deficiency. For 22 B12-deficient patients, there was no documentation of B12 replacement. Conclusions The PA cascade detected B12 deficiency in a significant number of inpatients with low-normal B12 levels that might have otherwise been missed; 28.8% of this group had PA for whom long-term B12 replacement is indicated. As treatment for B12 deficiency is inexpensive, non-toxic, and non-invasive, it is reasonable to evaluate B12 status by cascade testing which may provide additional diagnostic data beyond B12 level. Notable clinical practice findings from this study include the lack of B12 results in 173 of 326 discharge summaries, and no record of B12 supplementation in 22 of 59 patients with B12 deficiency. These gaps in documentation and follow-up may be associated with the relatively long turnaround time of MMA testing. Efforts at improving documentation, communication, and treatment of B12 deficiency are ongoing. Disclosures No relevant conflicts of interest to declare.

Abstract Accurate measurement of plasma von Willebrand factor (VWF) activity is essential for the laboratory diagnosis and treatment monitoring of von Willebrand disease (VWD). Currently available VWF activity assays include VWF ristocetin cofactor activity by manual light transmission platelet aggregometry (VWF:RCo–Agg) or flow cytometry (VWF:RCo–FL), collagen I and III binding activity (VWF:Co–I and –III) (Technozym), and platelet activity by latex agglutination (VWF:Lx) (Instrumental Laboratory). In this study we evaluated and compared the accuracy and precision of these 5 assay methods. Plasma samples from 11 normal donors and 41 patients categorized as type 1 (n=20) or type 2 (n=21) VWD based on clinical evaluation, fVIII:C activity, VWF:RCo–Agg, VWF antigen (VWF:Ag) level and plasma VWF multimer analysis by agarose gel electrophoresis were assayed for VWF activity by VWF:RCo–FL, VWF:Co–I, VWF:Co–III and VWF:Lx methods. The VWF:Ag/VWF activity ratio by VWF activity assay method was calculated for each sample. For normal donors and type I VWD patients, VWF:RCo–FL and VWF:Lx correlated well with VWF:RCo–Agg (R2=0.87, and 0.97, respectively), while VWF:Co–I and –III were lower compared to VWF:RCo-Agg. For type 2 VWD patients, different VWF:Ag/VWF activity ratio cutoffs (range 0.3–0.7) were used (Figure). Both VWF:RCo–Agg and –FL were sensitive (95%) and specific (97%) for type 2 VWD while the VWF:Lx was slightly less sensitive (81%) but was very specific (100%). VWF:Co–I and –III were the least sensitive (<90%) and specific (<90%); both methods had high false positive and negative rates for type 2 VWD. In Summary, for normals and type 1 VWD patients, VWF:RCo–FL and VWF:Lx correlate well with VWF:RCo–Agg and have similar sensitivities and specificities for type 2 VWD. VWF:Co–I and –III are unreliable for assessing plasma VWF activity.

Abstract Background Acquired factor X (FX) deficiency is associated with immunoglobulin light chain (AL) amyloidosis and may be accompanied by hemorrhage. There are limited data on the effects of autologous stem cell transplant (ASCT) on FX deficiency. We reviewed hemorrhagic complications and the effect of high dose melphalan (HDM) and ASCT on FX levels in AL amyloidosis patients with FX deficiency. Methods We conducted a retrospective chart review of patients with AL amyloid with FX levels below 60%, not on chronic anti-coagulation who underwent HDM/ASCT at the Mayo Clinic, Rochester, MN between 1995 and 2011. Results Forty-one of 358 patients (11%) met our study criteria. Median pre-ASCT FX was 45% (range: 2%, 59%). The most common bleeding complication was central line associated n=15 (37%) followed by gastrointestinal n=10 (24%) and genitourinary n=9 (22%). The most frequent and severe bleeding complications occurred in patients with FX levels less than 10%. Four patients required emergent splenectomy owing to splenic rupture; one of these patients died from hemorrhagic shock. Periprocedural prophylaxis included activated recombinant Factor VII (rFVIIa) infusions, fresh frozen plasma (FFP) infusions and platelet transfusions. rFVIIa was efficacious in controlling bleeding during splenectomy (n=5) and, in conjunction with arterial embolization, for retroperitoneal bleed (n=1). Elective splenectomy for FX deficiency (n=1) resulted in only transient improvement in FX level. No relationship between the degree of pre-ASCT FX deficiency and other laboratory values (alkaline phosphatase, AST, total bilirubin, serum albumin, total serum protein, serum creatinine, total urine protein, beta2 microglobulin, troponin T) was found. Post-ASCT FX levels were determined in seventeen patients. In four of these patients, post-ASCT FX levels were determined in the acute/subacute phase of ASCT before steady state FX levels could be achieved; the median change in FX for these patients was -6.5% (range: -19%, 3%). In the remaining thirteen patients, who were between 99 and 1920 days from ASCT, FX improved by median 26% (range: -15%, 92%). Overall post-ASCT FX increased in twelve of thirteen (92%) patients. The improvement in FX correlated with improvement in the degree of proteinuria (p = 0.04) and showed a trend towards significant correlation with improvement in serum alkaline phosphatase (p = 0.06). Conclusions Hemorrhagic complications are most frequent and severe for FX levels below 10%. rFVIIa infusions, FFP and platelets were effective prophylactic agents. In the single patient who underwent elective splenectomy, a transient improvement in FX level was seen. Splenectomy was otherwise reserved for patients with splenic rupture/hematoma. Post-ASCT FX levels increased in twelve (92.3%) of the remaining thirteen patients; five of the patients (38.5%) were no longer FX deficient after ASCT. The degree of improvement in FX levels was correlated with improvement in markers of renal or hepatic involvement by amyloid. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding.

Abstract Introduction Hereditary antithrombin (AT) deficiency is an autosomal dominant thrombophilia. It is classified into type 1 (quantitative) or type 2 (qualitative) deficiency based on the AT antigen and activity levels (Haemophilia 2008:14; 1229). The goal of this study was to correlate clinical phenotype with AT molecular defects. Methods After IRB approval, patients with a diagnosis of hereditary AT deficiency established at the Mayo Clinic, Rochester, were identified from the clinical database (1997-2012). AT activity was assayed by a chromogenic Factor Xa assay and AT antigen level was assayed by latex immunoassay. Peripheral blood leukocyte genomic DNA was extracted using standard methods. PCR-amplification and ABI BigDye Terminator cycle sequencing kit was performed for all SERPINC1 exons, intronic splicing regions and the 3’UTR. SERPINC1 sequence was analyzed using Mutation Surveyor software (SoftGenetics). Clinical data were obtained from patient interview and medical record review. An event was defined as an episode of venous thromboembolism (VTE), including deep vein thrombosis and/or pulmonary embolism; arterial thrombosis, including cerebrovascular event and/or myocardial infarction, and an obstetric event, including miscarriages and/or spontaneous abortions. Statistical analysis was performed with SAS 9.1.3 (SAS Institute Inc. Cary, NC). Results Of 30 patients with hereditary AT deficiency; sequence data was available on 22. Twenty-nine (97%) patients were white, and 19 (63%) were females. Six patients (20%) were smokers and 9 (30%) had a body mass index of >30. Based on the AT activity and antigen levels, 18 (81%) had type 1 AT deficiency, while the remainder had type 2. Eleven patients were heterozygous for six novel (all type 1) mutations. One patient was also a homozygous carrier for the Factor V Leiden mutation. The median age at first thrombotic event was 24.4 years (range, 16.2-70.7), and the median age at diagnosis of AT deficiency was 40.7 years (range, 17.8-76). Both, the median ages at first thrombotic event and at diagnosis were comparable in type 1 versus type 2 AT deficiency patients (P=0.52 and 0.97 respectively). Thirteen patients (43%) had unprovoked thrombotic events. Majority had VTE (n=21, 70%), which included one patient each with splanchnic venous thrombosis, and cerebral venous sinus thrombosis. At last follow up, twenty-one patients (70%) were on chronic anticoagulation [17 (81%) were on warfarin, 2 (9.5%) on enoxaparin and 2 (9.5%) were on rivaroxaban]. Median number of events was 1 (range 0-7). Four patients (19%) had bleeding complications from anticoagulation. Only one death was noted in the cohort and cause of death could not be determined. Conclusions Type 1 hereditary AT deficiency is the most clinically prevalent subtype in practice. Of the patients who developed thrombosis; clinical characteristics did not differ between type 1 and type 2 AT deficiency. We report 6 novel mutations in patients with hereditary AT deficiency. Disclosures: No relevant conflicts of interest to declare.