Safety and collection efficiency with a lower transfusion threshold for extracorporeal photopheresis in adult patients with graft-versus-host disease.

BACKGROUND: Extracorporeal photopheresis (ECP) is an established treatment for graft-versus-host disease (GVHD). Various haematocrit thresholds have been used to trigger red blood cells transfusion prior to ECP. Moderate-to-severe GVHD is frequently complicated by anaemia; the safety and collection efficiency with a lower haematocrit for ECP is unknown. METHODS: We prospectively enrolled 26 consecutive adult GVHD patients with haematocrits between 25% and 28·9% who received ECP on the CELLEX system. Preprocedural transfusion was withheld. We monitored the adverse events and transfusions avoided. A complete blood cell count with differential was performed on preprocedural peripheral blood and buffy coat collected. Lymphocyte fold enrichment (LFE) was compared between this cohort and two historical control groups with haematocrits of 29% or higher. RESULTS: Red Blood Cells transfusion was avoided in the lower-haematocrit cohort without adverse events. The median LFE was 4·5 (95%CI, 3·1-5·7) in the lower-haematocrit cohort and 5·2 (95%CI, 4·1-6·5) in the higher-haematocrit CELLEX-treated control group. The median difference was 0·7 (95%CI, -0·3 to 2·0, P = 0·14). It could not be established that the lower-haematocrit cohort was non-inferior to the higher-haematocrit control group with a prespecified non-inferiority margin of 1·3. However, LFE was significantly higher in the lower-haematocrit cohort than the higher-haematocrit UVAR XTS-treated control group (P < 0·01). CONCLUSION: Buffy coat can be collected for ECP using CELLEX in GVHD patients with a haematocrit of 25% or higher, with a collection efficiency superior to that in patients with higher haematocrits but treated using UVAR XTS. No increase in adverse events was observed at these lower haematocrits.

Use of signals and systems engineering to improve the safety of warfarin initiation.

Warfarin-dosing algorithms combine clinical factors and dosing history with the current international normalized ratio (INR) to estimate the therapeutic warfarin dose. Unfortunately, these approaches can result in an overdose if the INR is spuriously low. Our goal was to develop an alert mechanism based on prior INRs in addition to the current INR. Using data from the Genetics InFormatics Trial (GIFT) of Warfarin to Prevent DVT, we analyzed warfarin dose estimates for days 3 through 11 that were ≥10 % higher than an average of the previous two dose estimates. We fit a stepwise mixed model to current and prior dose estimates, and subsequently compared the root-mean-square-error (RMSE) in predicting the final therapeutic dose using the GIFT algorithm versus the mixed model. From 861 dosing records (obtain from 556 patients), 646 dosing records (75 %) were randomly selected for the derivation cohort and 215 dosing records (25 %) for the validation cohort. Using one prior dose estimate improved the accuracy of the warfarin dose estimate. Compared to a dose estimate based on current INR (GIFT algorithm), the mixed model reduced the RMSE in the derivation cohort by 0.0015 mg/day (RMSE 0.2079 vs. 0.2094; p = 0.039). In the validation cohort, the RMSE reduction was not significant. A mixed model of dose estimates based on the current and most recent INRs shows potential to improve the safety of warfarin dosing. Clinicians should be cautious about aggressively escalating the warfarin dose after an INR that is lower than expected.

Novel anticoagulants and laboratory testing.

The introduction of several oral direct anticoagulants within the past 2-3 years has dramatically changed clinical practice and has also impacted on utilization and interpretation of coagulation laboratory testing. This article reviews the effects of the oral thrombin inhibitor, dabigatran, and the oral factor Xa inhibitors, rivaroxaban and apixaban, on screening and diagnostic coagulation tests, and describes methods for measuring the their anticoagulant activity in plasma. Currently, there are evidence gaps regarding the role of laboratory testing for surveillance and management of adverse events associated with these new anticoagulants which do not require routine therapeutic drug monitoring. This is a rapidly changing field, and coagulation laboratory experts have a major role in ensuring patients receive appropriate testing and accurate interpretations of results.

Genetics informatics trial (GIFT) of warfarin to prevent deep vein thrombosis (DVT): rationale and study design.

The risk of venous thromboembolism (VTE) is higher after the total hip or knee replacement surgery than after almost any other surgical procedure; warfarin sodium is commonly prescribed to reduce this peri-operative risk. Warfarin has a narrow therapeutic window with high inter-individual dose variability and can cause hemorrhage. The genetics-informatics trial (GIFT) of warfarin to prevent deep vein thrombosis (DVT) is a 2 × 2 factorial-design, randomized controlled trial designed to compare the safety and effectiveness of warfarin-dosing strategies. GIFT will answer two questions: (1) does pharmacogenetic (PGx) dosing reduce the rate of adverse events in orthopedic patients; and (2) is a lower target international normalized ratio (INR) non-inferior to a higher target INR in orthopedic participants? The composite primary endpoint of the trial is symptomatic and asymptomatic VTE (identified on screening ultrasonography), major hemorrhage, INR ≥ 4, and death.

Blast flagging with the UniCel DxH 800 Coulter Cellular Analysis System.

We recently conducted a series of evaluations of the new UniCel DxH 800 Coulter Cellular Analysis System at Barnes-Jewish Hospital in St. Louis, Missouri. This report addresses issues relating to the flagging performance of the DxH 800, especially as it relates to the detection of blast cells. The DxH 800 was designed with major performance and hardware enhancements over the previous LH series analyzer. Capturing 29 individual measurements per cell analyzed, the system provides improved sensitivity and specificity, which means more reliable assessment of abnormal cell populations. We undertook these particular studies to assess these enhancements and to evaluate the analytical performance of the DxH 800's automated white blood cell differential and flagging of abnormal blood samples. Our studies placed specific emphases on the detection of blast cells. The Initial evaluation of the ability of the DxH 800 to flag blast cells was remarkable. We ran 95 samples containing > or =1% blasts on both the Beckman Coulter LH 750 and DxH 800 instruments. Whereas the LH 750 had a 6.4% false-negative rate, the DxH 800 had a 0.0% false-negative rate. We then conducted an extensive study of 435 blast-positive samples on the LH 750, 302 of which were analyzed on the DxH 800 and 94 of which were analyzed on Siemens' ADVIA 2120 Hematology System. With a 0.3% false-negative rate, the DxH 800 outperformed the LH 750, which had a 9.6% false-negative rate. In a previous study of 311 random patient samples, the overall success rate of the DxH 800 in detecting abnormal samples in a mixed population of samples resulted in fewer false negatives (3 versus 6) and significantly fewer false positives (60 versus 152) than the LH 750. The lower rate of false positives for the DxH 800 dramatically reduced the number of unnecessary smear reviews that otherwise would have to be run on the LH 750. The DxH 800 has demonstrated that it is capable of reducing the number of unnecessary differentials performed, while performing better at detecting samples with abnormalities, particularly when blast cells are present.

Integration of genetic, clinical, and INR data to refine warfarin dosing.

Well-characterized genes that affect warfarin metabolism (cytochrome P450 (CYP) 2C9) and sensitivity (vitamin K epoxide reductase complex 1 (VKORC1)) explain one-third of the variability in therapeutic dose before the international normalized ratio (INR) is measured. To determine genotypic relevance after INR becomes available, we derived clinical and pharmacogenetic refinement algorithms on the basis of INR values (on day 4 or 5 of therapy), clinical factors, and genotype. After adjusting for INR, CYP2C9 and VKORC1 genotypes remained significant predictors (P < 0.001) of warfarin dose. The clinical algorithm had an R(2) of 48% (median absolute error (MAE): 7.0 mg/week) and the pharmacogenetic algorithm had an R(2) of 63% (MAE: 5.5 mg/week) in the derivation set (N = 969). In independent validation sets, the R(2) was 26-43% with the clinical algorithm and 42-58% when genotype was added (P = 0.002). After several days of therapy, a pharmacogenetic algorithm estimates the therapeutic warfarin dose more accurately than one using clinical factors and INR response alone.

A polymorphism in the VKORC1 regulator calumenin predicts higher warfarin dose requirements in African Americans.

Warfarin demonstrates a wide interindividual variability in response that is mediated partly by variants in cytochrome P450 2C9 (CYP2C9) and vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1). It is not known whether variants in calumenin (CALU) (vitamin K reductase regulator) have an influence on warfarin dose requirements. We resequenced CALU regions in a discovery cohort of dose outliers: patients with high (>90th percentile, n = 55) or low (<10th percentile, n = 53) warfarin dose requirements (after accounting for known genetic and nongenetic variables). One CALU variant, rs339097, was associated with high doses (P = 0.01). We validated this variant as a predictor of higher warfarin doses in two replication cohorts: (i) 496 patients of mixed ethnicity and (ii) 194 African-American patients. The G allele of rs339097 (the allele frequency was 0.14 in African Americans and 0.002 in Caucasians) was associated with the requirement for a 14.5% (SD +/- 7%) higher therapeutic dose (P = 0.03) in the first replication cohort and a higher-than-predicted dose in the second replication cohort (allele frequency 0.14, one-sided P = 0.03). CALU rs339097 A>G is associated with higher warfarin dose requirements, independent of known genetic and nongenetic predictors of warfarin dose in African Americans.

Ability of VKORC1 and CYP2C9 to predict therapeutic warfarin dose during the initial weeks of therapy.

BACKGROUND: CYP2C9 and VKORC1 genotypes predict therapeutic warfarin dose at initiation of therapy; however, the predictive ability of genetic information after a week or longer is unknown. Experts have hypothesized that genotype becomes irrelevant once international normalized ratio (INR) values are available because INR response reflects warfarin sensitivity. METHODS: We genotyped the participants in the Prevention of Recurrent Venous Thromboembolism (PREVENT) trial, who had idiopathic venous thromboemboli and began low-intensity warfarin (therapeutic INR 1.5-2.0) using a standard dosing protocol. To develop pharmacogenetic models, we quantified the effect of genotypes, clinical factors, previous doses and INR on therapeutic warfarin dose in the 223 PREVENT participants who were randomized to warfarin and achieved stable therapeutic INRs. RESULTS: A pharmacogenetic model using data from day 0 (before therapy initiation) explained 54% of the variability in therapeutic dose (R(2)). The R(2) increased to 68% at day 7, 75% at day 14, and 77% at day 21, because of increasing contributions from prior doses and INR response. Although CYP2C9 and VKORC1 genotypes were significant independent predictors of therapeutic dose at each weekly interval, the magnitude of their predictive ability diminished over time: partial R(2) of genotype was 43% at day 0, 12% at day 7, 4% at day 14, and 1% at day 21. CONCLUSION: Over the first weeks of warfarin therapy, INR and prior dose become increasingly predictive of therapeutic dose, and genotype becomes less relevant. However, at day 7, genotype remains clinically relevant, accounting for 12% of therapeutic dose variability.

Prediction and management of bleeding in cardiac surgery.

Excessive bleeding after cardiac surgery can result in increased morbidity and mortality related to transfusion- and hypoperfusion-related injuries to critical organ systems. Our objective was to review mechanisms that result in bleeding after cardiac surgery as well as current and emerging interventions to reduce bleeding and transfusion. We discovered that of point-of-care (POC) tests of hemostatic function can facilitate the optimal management of excessive bleeding and reduce transfusion by facilitating administration of specific pharmacologic or transfusion-based therapy and by allowing physicians to better differentiate between microvascular bleeding and surgical bleeding. Emerging interventions like recombinant FVIIa have the potential to reduce bleeding and transfusion-related sequelae and may be life-saving; however, randomized, controlled trials are needed to confirm safety before they can be used as either first-line therapies for bleeding or bleeding prophylaxis. In conclusion, careful investigation of the role of new interventions is essential as the ability to reduce use of blood products, to decrease operative time and/or re-exploration rates has important implications for overall patient safety and health care costs.

Laboratory and clinical outcomes of pharmacogenetic vs. clinical protocols for warfarin initiation in orthopedic patients.

BACKGROUND: Warfarin is commonly prescribed for prophylaxis and treatment of thromboembolism after orthopedic surgery. During warfarin initiation, out-of-range International Normalized Ratio (INR) values and adverse events are common. METHODS: In orthopedic patients beginning warfarin therapy, we developed and prospectively validated pharmacogenetic and clinical dose refinement algorithms to revise the estimated therapeutic dose after 4 days of therapy. RESULTS: The pharmacogenetic algorithm used the cytochrome P450 (CYP) 2C9 genotype, smoking status, peri-operative blood loss, liver disease, INR values and dose history to predict the therapeutic dose. The R(2) was 82% in a derivation cohort (n = 86) and 70% when used prospectively (n = 146). The R(2) of the clinical algorithm that used INR values and dose history to predict the therapeutic dose was 57% in a derivation cohort (n = 178) and 48% in a prospective validation cohort (n = 146). In 1 month of prospective follow-up, the percent time spent in the therapeutic range was 7% higher (95% CI: 2.7-11.7) in the pharmacogenetic cohort. The risk of a laboratory or clinical adverse event was also significantly reduced in the pharmacogenetic cohort (Hazard Ratio 0.54; 95% CI: 0.30-0.97). CONCLUSIONS: Warfarin dose adjustments that incorporate genotype and clinical variables available after four warfarin doses are accurate. In this non-randomized, prospective study, pharmacogenetic dose refinements were associated with more time spent in the therapeutic range and fewer laboratory or clinical adverse events. To facilitate gene-guided warfarin dosing we created a non-profit website, http://www.WarfarinDosing.org.

Use of pharmacogenetic and clinical factors to predict the therapeutic dose of warfarin.

Initiation of warfarin therapy using trial-and-error dosing is problematic. Our goal was to develop and validate a pharmacogenetic algorithm. In the derivation cohort of 1,015 participants, the independent predictors of therapeutic dose were: VKORC1 polymorphism -1639/3673 G>A (-28% per allele), body surface area (BSA) (+11% per 0.25 m(2)), CYP2C9(*)3 (-33% per allele), CYP2C9(*)2 (-19% per allele), age (-7% per decade), target international normalized ratio (INR) (+11% per 0.5 unit increase), amiodarone use (-22%), smoker status (+10%), race (-9%), and current thrombosis (+7%). This pharmacogenetic equation explained 53-54% of the variability in the warfarin dose in the derivation and validation (N= 292) cohorts. For comparison, a clinical equation explained only 17-22% of the dose variability (P < 0.001). In the validation cohort, we prospectively used the pharmacogenetic-dosing algorithm in patients initiating warfarin therapy, two of whom had a major hemorrhage. To facilitate use of these pharmacogenetic and clinical algorithms, we developed a nonprofit website, http://www.WarfarinDosing.org.

An evaluation of the utility of performing body fluid counts on the coulter LH 750.

Performing a manual body fluid count is a tedious, time-consuming, and frequently imprecise process for any clinical laboratory. The ability to perform many of these counts with an automated hematology analyzer has the real potential of making a major impact on laboratory precision and productivity. The manual chamber count is fraught with many variables and is often very technologist/technique dependent, often leading to inaccuracies in test results. Our laboratory undertook a series of studies designed to evaluate the capability of the Coulter LH 750 hematology analyzer to supplement our current manual method in the performance of body fluid analysis. First, we established the performance of our current manual counting method, the gold standard against which LH 750 performance would be judged. We looked at the precision of manual cell counting by having 4 technologists perform manual counts on each of 35 spinal, synovial, peritoneal, and other fluids with white blood cell (WBC) and/or red blood cell (RBC) counts of greater than 0.3 x 10(9) /L and 0.03 x 10(12) /L, respectively. Our results support earlier reports that the variability in counts among technologists using the manual chamber cell count methods is often very significant. After each sample was manually counted, it was analyzed on the Coulter LH 750, and the results were compared with those of our current manual method. Results showed good correlation between the manual and LH 750 methods. Next, we conducted a series of separate tests to evaluate the stability of different cellular elements (WBCs and RBCs) in each of these body fluid types. The study consisted of 2 sets of 4--3-mL samples of each fluid type--which were analyzed on the LH 750 immediately on receipt and after 1 hour, 4 hours, 8 hours, 16 hours, and 24 hours. The findings suggested varying degrees of stability that were dependent on fluid type and initial cell concentration. Finally, we looked at whether it is necessary to perform background counts before analyzing each body fluid sample and the impact of automating body fluid counts on our workload.

Massive retroperitoneal pseudotumour in a patient with type 3 von Willebrand disease.

Formation of destructive haemorrhagic pseudocysts or pseudotumours thought to arise from unresolved, encapsulated haematomas is a well-recognized, rare complication of severe haemophilia A or B, and has been reported in a single patient with von Willebrand disease (vWD). We report a 41-year-old patient with type 3 vWD who underwent incomplete resection of a large retroperitoneal pseudocyst in 1995 and presented with a recurrent, extensive right abdominal and flank mass and signs and symptoms of large bowel obstruction. He required emergency partial colectomy for bowel ischaemia and removal of his right kidney, which was hydronephrotic due to prolonged ureteral obstruction by the pseudocyst. Following repeat partial resection of the pseudotumour, he developed persistent bleeding into the operative site despite aggressive administration of von Willebrand factor (vWF)-rich factor VIII concentrates, resulting in retroperitoneal haematomas and abscesses, which resolved after 13 months of percutaneous drainage, extended supplementation of vWF and antibiotic therapy.

Postpartum coronary artery dissection complicated by heparin-induced thrombocytopenia and thrombosis.

A 32-year-old woman presented with an acute anterior-lateral myocardial infarction 7 days postpartum. Coronary angiography revealed an occlusive left main coronary artery dissection. After coronary artery bypass surgery the patient's cardiac function improved and stabilized. Thrombocytopenia and a femoral artery thrombosis after 9 days of heparin exposure marked the development of heparin-induced thrombocytopenia and thrombosis that was successfully managed with argatroban, a direct thrombin inhibitor anticoagulant.

Pancytopenia after removal of copper from total parenteral nutrition.

Patients who develop cholestatic jaundice during chronic total parenteral nutrition (TPN) can develop significant hematologic complications due to hypocupremia if copper supplementation is withheld. A 36-year-old female with short bowel syndrome developed progressive liver dysfunction 6 months after initiation of TPN. Trace elements were omitted from her TPN because of cholestasis and persistent hyperbilirubinemia. Despite chronic diarrhea, absorption of some dietary copper was anticipated from her oral diet. Fifteen months later, the patient became red cell transfusion dependent, and her neutrophil and platelet counts steadily declined. After 19 months of receiving TPN without trace elements, her serum copper level was 25 microLg/dL (normal: 70 to 155 microg/dL). Provision of trace elements for 2 months was associated with increased serum copper, neutrophil and platelet counts and independence from red cell transfusions. When the serum copper level reached 186 microg/dL, copper supplementation was discontinued. Over the next 3 months, serum copper level fell to 10 microg/dL, neutrophil and platelet counts fell precipitously, and red cell transfusions were resumed. Once again, copper, neutrophil and platelet levels promptly rebounded with parenteral copper supplementation. Although anemia and neutropenia are well-recognized hematologic consequences of copper deficiency, thrombocytopenia rarely has been reported. This is the first report of pancytopenia secondary to TPN-related copper deficiency in which the association was confirmed when hypocupremia recurred.