College of American Pathologists Conference XXXI on laboratory monitoring of anticoagulant therapy: laboratory monitoring of unfractionated heparin therapy.

OBJECTIVE: To review the state of the art as reflected in the medical literature and the consensus opinion of recognized experts in the field regarding the laboratory monitoring of unfractionated heparin therapy. DATA SOURCES, EXTRACTION AND SYNTHESIS: The authors made an extensive review of the literature. The draft manuscript was circulated to every participant in the consensus conference prior to the convening of the conference. Extensive discussion concerning all of the issues addressed in the manuscript as well as the resulting recommendations occurred. This information was then used to revise the manuscript into its final form. CONCLUSIONS: The resulting manuscript has 23 specific recommendations regarding preanalytic, analytic, and postanalytic phases of monitoring and testing for complications related to unfractionated heparin therapy. This report contains detailed discussion of these recommendations and includes literature citations that support them. A number of issues for which consensus could not be reached are also discussed. A method is provided to assist laboratories, particularly small laboratories, in providing clinicians with an appropriate therapeutic range for the activated partial thromboplastin time, the most commonly used test in monitoring heparin therapy.

Dose-intensive melphalan with blood stem-cell support for the treatment of AL (amyloid light-chain) amyloidosis: survival and responses in 25 patients.

AL (amyloid light-chain) amyloidosis is an uncommon plasma cell disorder in which depositions of amyloid light-chain protein cause progressive organ failure and death in a median of 13 months. Autologous stem-cell transplantation is effective therapy for multiple myeloma and therefore, we evaluated its efficacy for AL amyloidosis. Patients with adequate cardiac, pulmonary, and renal function had stem cells mobilized with granulocyte-colony stimulating factor and were treated with dose-intensive intravenous melphalan (200 mg/m2). Response to therapy was determined by survival and improvement of performance status, complete response or persistence of the clonal plasma cell disorder, and change in the function of organs involved with amyloid at baseline. We enrolled 25 patients with a median age of 48 years (range, 29-60), all of whom had biopsy-proven amyloidosis with clonal plasma cell disorders. Twenty-two (88%) were Southwest Oncology Group performance status 1 or 2 within a year of diagnosis, and 16 (64%) had received no prior therapy. Predominant amyloid-related organ involvement was cardiac (n = 8), renal (n = 7), hepatic (n = 6), neuropathic (n = 3), and lymphatic (n = 1). Fifteen patients had one or two organ systems involved, whereas 10 had three or more involved. With a median follow-up of 24 months (12-38), 17 of 25 patients (68%) are alive, and the median survival has not been reached. Thirteen of 21 patients (62%) evaluated 3 months posttransplant had complete responses of their clonal plasma cell disorders. Currently, two thirds of the surviving patients (11 of 17) have experienced improvements of amyloid-related organ involvement in all systems, whereas 4 of 17 have stable disease. The improvement in the median performance status of the 17 survivors at follow-up (0 [range, 0-3]) is statistically significant versus baseline (2 [range, 1-3]; P < . 01). Significant negative prognostic factors with respect to overall survival include amyloid involvement of more than two major organ systems and predominant cardiac involvement. Three patients have experienced relapses of the clonal plasma cell disorder at 12 and 24 months. Dose-intensive therapy should currently be considered as the preferred therapy for patients with AL amyloidosis who meet functional criteria for autologous transplantation.

The preoperative bleeding time test lacks clinical benefit: College of American Pathologists' and American Society of Clinical Pathologists' position article.

The major conclusions of this position article are as follows: (1) In the absence of a history of a bleeding disorder, the bleeding time is not a useful predictor of the risk of hemorrhage associated with surgical procedures. (2) A normal bleeding time does not exclude the possibility of excessive hemorrhage associated with invasive procedures. (3) The bleeding time cannot be used to reliably identify patients who may have recently ingested aspirin or nonsteroidal anti-inflammatory agents or those who have a platelet defect attributable to these drugs. The best preoperative screen to predict bleeding continues to be a carefully conducted clinical history that includes family and previous dental, obstetric, surgical, traumatic injury, transfusion, and drug histories. A history suggesting a possible bleeding disorder may require further evaluation; such an evaluation may include performance of the bleeding time test, as well as a determination of the platelet count, the prothrombin time, and the activated partial thromboplastin time. In the absence of a history of excessive bleeding, the bleeding time fails as a screening test and is, therefore, not indicated as a routine preoperative test.

Mobilized CD34+ cells selected as autografts in patients with primary light-chain amyloidosis: rationale and application.

BACKGROUND: Concern about tumor cell contamination in stem cell preparations has led to the use of CD34+ cell selection as a means of purging. Increasing the number of CD34+ cells per leukapheresis may help to provide an adequate dose of CD34+ cells. STUDY DESIGN AND METHODS: The reverse transcriptase polymerase chain reaction (RT-PCR) was employed to clone overexpressed clonotypic immunoglobulin light-chain variable region genes (Ig VL) from bone marrows of patients with primary light-chain amyloidosis (AL). Patient-specific primers were designed to evaluate stem cell collections for contamination. CD34+ cell selection was performed on components from AL patients who underwent mobilization with granulocyte-colony-stimulating factor (G-CSF) (filgrastim; 16 microg/kg/d for 4 days) and collection by large-volume leukapheresis (LVL;25L) on Days 4 and 5. The selected cells alone were transfused after patients received mephalan (200 mg/m2). RESULTS: Contamination was found in collections from 4 to 7 patients, which provided the rationale for a subsequent trial of CD34+ cell selection. The median number of CD34+ cells per kg collected on Days 4 and 5, and in toto, was 4.0 x 10(6)(1.1-12.7), 7.9 x 10(6)(1.8-12.7), and 10.7 x 10(6)(2.9-25.4), respectively (n = 9 patients). The median yield per selection was 38 percent, with a purity of 85 percent (45-97%), and the viability of CD34+ cells averaged 96.4 +/- 3.6 percent (n = 18 selections). The median number of CD34+ cells infused was 5.9 x 10(6) per kg (2.1-10.1). In comparison with AL patients given unselected autografts, patients receiving selected CD34+ cells experienced similar reconstitution of neutrophils and platelets but slower lymphocyte recovery. CONCLUSION: Patients with AL often have contamination with clonotypic cells in their blood autografts. G-CSF mobilization and LVL provide components that allow the selection of adequate doses of CD34+ cells. The use of CD34+ cells in patients with AL achieves rapid neutrophil and platelet recovery but delayed lymphocyte recovery. CD34+ cell selection is feasible in the treatment of AL, but its effectiveness in purging clonotypic cells remains to be ascertained.

Collection of mobilized blood progenitor cells for hematopoietic rescue by large-volume leukapheresis.

BACKGROUND: Mobilized blood progenitor cells rapidly reconstitute hematopoiesis in patients after dose-intensive chemotherapy. However, optimal timing and methods of mobilized blood progenitor cell collection have yet to be fully defined. STUDY DESIGN AND METHODS: The utility of large-volume leukapheresis (LVL; > 15 L blood processed) in collecting target doses of mononuclear cells (7 x 10(8)/kg) for use in autologous hematopoietic rescue was investigated. LVL was begun at a standardized interval (14 days) after a course of limited chemotherapy and subsequent daily recombinant human granulocyte-macrophage-colony-stimulating factor administration to mobilize blood progenitor cells into the circulation. With each LVL procedure, mononuclear cells, colony-forming units-granulocyte-macrophage (CFU-GM), burst-forming units-erythroid, mixed colonies, total clonogenic progenitor cells, and CD34+ cells collected per kg of patient weight were counted. After high-dose chemotherapy and infusion of cryopreserved mobilized blood progenitor cells, the days needed for neutrophils to reach levels of > 0.5 x 10(9) per L and for platelets to reach levels of > 20 x 10(9) per L were recorded. RESULTS: In 14 previously treated cancer patients, an average of 28.9 +/- 4.9 L of blood was processed per LVL (n = 35) to collect medians of 2.5 x 10(8) mononuclear cells per kg (range, 1.0-7.4), 14 x 10(4) CFU-GM per kg (0-208), 27 x 10(4) clonogenic progenitor cells per kg (0-370), and 2.8 x 10(6) CD34+ cells per kg (0-112.5). Fifty-seven percent of patients (8/14) required one or two LVL procedures to collect adequate blood progenitor cells (range, 1-4). After dose-intensive chemotherapy, 13 patients received medians of 6.8 x 10(8) mononuclear cells per kg (range, 5.1-9.9), 53 x 10(4) CFU-GM per kg (9-208), and 12 x 10(6) CD34+ cells per kg (3.6-112.5). Rapid hematopoietic reconstitution occurred with 10 days (range, 8-12) and 9 days (6-15), respectively, for neutrophil and platelet recoveries. CONCLUSION: Scheduled LVL, beginning on Day 14 after the administration of granulocyte-macrophage-colony-stimulating factor following chemotherapy, is a convenient and efficient method of collecting blood progenitor cells. The mononuclear cells so obtained effected consistent and rapid hematopoietic reconstitution in a highly reproducible manner in a group of heavily treated patients.

Performance characteristics of fibrinogen assays. Results of the College of American Pathologists Proficiency Testing Program 1988-1991.

Plasma fibrinogen concentration appears to be an important risk factor for the development of atherosclerotic cardiovascular disease of a similar magnitude to cholesterol. The quality control of plasma fibrinogen assays has taken on new importance as a consequence of this potential role as an atherosclerotic risk factor. This article reviews the performance characteristics of 40,000 fibrinogen assays comprising the College of American Pathologists Proficiency Testing Program from 1988 through 1991. Instrument and reagent variables both play roles in the poor interlaboratory reproducibility documented by this study. The absence of either a national or international standard for plasma fibrinogen assays has been a major source of reagent variability. The validation and calibration of the College of American Pathologists lyophilized plasma reference preparation for fibrinogen determination is also reported in this study. The availability of this validated reference plasma should markedly improve interlaboratory reproducibility.

Hyperfibrinogenemia. An important risk factor for vascular complications in diabetes.

OBJECTIVE: To evaluate the determinants of elevated fibrinogen levels and the impact of hyperfibrinogenemia on vascular complications in diabetes. RESEARCH DESIGN AND METHODS: Plasma fibrinogen, glucose, HbA1, and lipids were measured in 116 ambulatory type I and type II diabetic patients with (n = 59) or without (n = 57) clinical evidence of micro- or macrovascular complications. In 56 of these patients, factor VII activity and CRP also were measured. Univariate and multivariate data analyses were conducted. RESULTS: Overall mean +/- SE fibrinogen levels in patients (339 +/- 7.3 mg/dl) were elevated markedly compared with control subjects (248 +/- 9.1 mg/dl). Fibrinogen levels were elevated disproportionately in patients with type II diabetes (P less than 0.0001), hypertension (P = 0.0001), obesity (P less than 0.0001), and vascular complications (P less than 0.0001). Fibrinogen was correlated significantly with age (P less than 0.001), cholesterol (P = 0.002), CRP (P less than 0.001), and factor VII activity (P = 0.032), but not with plasma glucose, triglycerides, HDL cholesterol, or disease duration. Stepwise multiple regression analyses revealed that type II diabetes and presence of vascular complications were major determinants of fibrinogen. For vascular complications, fibrinogen emerged as one of only three independent predictors, the other two being diabetes duration and hypertension.

Factors affecting the performance of factor VIII coagulant activity assays. Results of proficiency surveys of the College of American Pathologists.

To evaluate sources of interlaboratory variation in factor VIII coagulant assays and the effects of uniform calibration on it, data were analyzed from Survey Set H2-C, 1987, of the College of American Pathologists, Northfield, Ill, into which the College of American Pathologists Reference Preparation for Factor VIII was incorporated. Peer group performance and its improvement by uniform calibration were evaluated by comparing means, precisions, and numbers of acceptable survey scores. Results showed a poorer performance by less experience laboratories and by those that used undesirable calibrators. Substantial improvement was seen with uniform calibration, especially among laboratories that had employed poorer calibrators. Although variance component analysis showed that the type of calibrator was the most important contributor to interlaboratory variation, it accounted for only 10% of total variability. Participant summaries and questionnaires that spanned several years revealed steady improvement in methodology but no striking changes in interlaboratory variation.

Tissue calcification after orthotopic liver transplantation. An autopsy study.

A retrospective review of 25 patients who underwent orthotopic liver transplantation was performed to relate the prevalence and preferred sites of microscopic calcium deposition seen at autopsy to clinical parameters, namely, hypercalcemia, hypercalcemia, hyperphosphatemia, and renal failure. Microscopic foci of calcification were noted in 84% of patients, and hypercalcemia was noted in 68%. Multiple regression analysis demonstrated that the number of microscopically calcified organs depended in part on the peak total serum calcium level and the duration of hypercalcemia and that the peak total serum calcium level depended in part on the peak phosphorus level and the quantity of calcium administered intraoperatively. Univariate analysis showed that peak phosphorus level was partially dependent on the peak creatinine level. The data suggest that hypercalcemia and postoperative ectopic calcification are common and related occurrences following hepatic transplantation and that intraoperative manipulations of serum calcium levels and renal failure partially, but not entirely, account for this phenomenon.

Vancomycin stability in heparin and total parenteral nutrition solutions: novel approach to therapy of central venous catheter-related infections.

To facilitate therapy of central venous catheter-related Gram-positive bacterial infection in patients who require total parenteral nutrition (TPN) therapy, we studied the stability of vancomycin in a commonly used TPN solution (V-TPN) at final concentrations of 0.5 mg/mL and 1.0 mg/mL and in heparin (100 U/mL in 0.9% NaCl) at 25 micrograms/mL (V-H). Vancomycin concentrations in V-TPN and V-H after storage at 4 degrees C over 35 and 14 days, respectively, were stable (within 10% of the prestorage vancomycin concentration). After 14 days at 4 degrees C heparin activity in V-H solution was 100 +/- 4% of that noted initially. Vancomycin remained stable (100 +/- 6% of the original vancomycin concentration) when the previously refrigerated V-TPN was held for an additional 24 hours at 22 degrees C. When the previously refrigerated V-H was held for an additional 24 hours at 37 degrees C, vancomycin concentrations decreased to 78 +/- 9% of the baseline concentrations (p less than .001). The stability of vancomycin in this TPN solution allows the daily dose of vancomycin to be mixed with the solution and then infused over 10 hours. As shown with pharmacokinetic modeling, this form of therapy will achieve serum vancomycin concentrations within the therapeutic range throughout a 24-hour period. The relative stability of vancomycin in a heparin line-flush solution allows vancomycin concentration in the lumen of the catheter to be maintained at greater than or equal to 15 micrograms/mL during the interval between catheter flushing and the subsequent TPN infusion. A simplified method of administering vancomycin to patients receiving concurrent TPN is possible.

Histopathology of the donor gallbladder removed at orthotopic liver transplantation: correlation with graft function.

The histopathology of 50 consecutive donor gallbladders removed during orthotopic liver transplantation was reviewed and correlated with graft function. Multiple sections of the gallbladders were examined for the presence of mucosal congestion, hemorrhage, and necrosis, without prior knowledge of the clinical outcome. Each pathologic feature was graded as absent (0), involving less than 10% (1+), 10% to 50% (2+), or more than 50% (3+) of the histologically examined mucosa. Graft function was determined by two transplant surgeons, a poor diagnosis being worsening of liver function tests associated with declining mental status and resulting in immediate retransplantation or early postoperative death; all others were categorized as good. Of 39 patients with good graft function, 18 had normal donor gallbladders, 11 had congestion only, and 10 had hemorrhage and/or necrosis. Of 11 patients with poor graft function, eight had hemorrhage and/or necrosis (2+ in seven), three had congestion only, and none had a normal gallbladder mucosa. Congestion alone was found to be a poor predictor of graft damage. Presence of any grade of hemorrhage and/or necrosis in donor gallbladders as related to poor liver graft function had a sensitivity of 73%, a specificity of 74%, a positive predictive value of 44%, and a negative predictive value of 91%. When hemorrhage and/or necrosis of 2+ severity was separately grouped and correlated with poor graft function, the specificity rose to 97% and the positive predictive value to 88%, and the negative predictive value was similar at 90%. We conclude that donor gallbladders often show mucosal abnormalities consisting of varying degrees of congestion, hemorrhage, and necrosis. The finding of hemorrhage and/or necrosis affecting more than 10% of the mucosa appears to be a specific lesion of ischemic damage that correlates highly with poor liver graft function.

Effect of lupus anticoagulants on the activated partial thromboplastin time. Results of the College of American Pathologists survey program.

Lupus anticoagulants are antibodies that interfere with in vitro phospholipid-dependent coagulation reactions. In vivo, they have been associated with a variety of thromboembolic problems. Samples from patients with lupus anticoagulants were included in the 1986 and 1987 College of American Pathologists proficiency survey program. Participant performance on these samples demonstrated significant variation in the responsiveness of different activated partial thromboplastin reagents to lupus anticoagulants. The level of factor VIII in these samples reported by the participants also varied with the reagent used. Follow-up studies demonstrated striking reagent-dependent differences in the dilutional effect on apparent factor VIII, IX, XI, and XII activity. These results point out the importance of selecting sensitive and responsive reagents for appropriate identification of lupus inhibitors. In addition, the results indicate that the choice of reagent used for factor assays can affect the apparent factor activity as well as whether a dilutional effect is noted when a lupus anticoagulant is present in the test sample, an important consideration when trying to distinguish a lupus anticoagulant from a specific factor inhibitor.

Very low doses of warfarin can prevent thrombosis in central venous catheters. A randomized prospective trial.

OBJECTIVE: To determine whether very low doses of warfarin are useful in thrombosis prophylaxis in patients with central venous catheters. DESIGN: Patients at risk for thrombosis associated with chronic indwelling central venous catheters were prospectively and randomly assigned to receive or not to receive 1 mg of warfarin, beginning 3 days before catheter insertion and continuing for 90 days. Subclavian, innominate, and superior vena cava venograms were done at onset of thrombosis symptoms or after 90 days in the study. RESULTS: One hundred twenty-one patients entered the study, and 82 patients completed the study. Of 42 patients completing the study while receiving warfarin, 4 had venogram-proven thrombosis. All 4 had symptoms from thrombosis. Of 40 patients completing the study while not receiving warfarin, 15 had venogram-proven thrombosis, and 10 had symptoms from thrombosis (P less than 0.001). There were no measurable changes in the coagulation values assayed due to this warfarin dose, except in occasional patients who had become anorectic because of their disease or chemotherapy. CONCLUSIONS: Very low doses of warfarin can protect against thrombosis without inducing a hemorrhagic state. This approach may be applicable to other groups of patients.

Evaluation of APTT reagent sensitivity to factor IX and factor IX assay performance. Results from the College of American Pathologists Survey Program.

Hereditary factor IX deficiency (hemophilia B) is among the more common hereditary bleeding disorders and factor IX assays are among the more common specific factor assays performed by coagulation laboratories. To assess the sensitivity of various reagents used for performance of activated partial thromboplastin times and factor IX assays, a series of samples with varying levels of factor IX were included in the 1988 College of American Pathologists Survey Program. We found significant differences in the sensitivity of reagents to factor IX deficiency. Surprisingly, the least sensitive reagents were among the most commonly used reagents. Significant differences in the classification of activated partial thromboplastin times as abnormal were noted between H1 and H2 survey participants. As with factor VIII assays, significant differences in the dose-response curves for factor IX deficiency were noted between reagents, with more responsive reagents giving more precise results for factor IX assays. Comparison of factor IX assay performance in 1988 with 1980 performance indicates a substantial improvement in assay precision. However, a further improvement in assay performance could be expected if current recommendations were followed.

How many patients are necessary to assess test performance?

Test performance characteristics are important in assessing the clinical usefulness of laboratory tests and serve as a basis for comparing one test to another. Statistical comparisons of performance characteristics are meaningful only when they can detect medically important differences; that is, when they provide adequate statistical power. This requires choosing the appropriate sample size in determining the performance characteristics of interest. Using standard formulas, we designed tables that provide such sample size requirements. Example problems of sample size determination in laboratory test comparisons are given. Used appropriately, this approach should result in better studies of laboratory tests and fewer meaningless negative studies.

Fibrinolysis during liver transplantation in humans: role of tissue-type plasminogen activator.

Human liver transplantation is frequently associated with a coagulopathy and bleeding diathesis developing during the anhepatic phase of surgery. The hemostatic defect has been attributed in part to accelerated fibrinolysis. In this study we evaluated changes in specific blood fibrinolytic parameters occurring in eight adult patients undergoing first-time orthotopic liver transplantation. Five of the eight patients experienced moderate to severe systemic fibrinolysis as reflected by alpha 2-antiplasmin consumption and fibrinogen degradation with the concomitant appearance of fibrin(ogen) degradation products. In association with these changes, an increase in tissue-type plasminogen activator (t-PA) activity and t-PA antigen levels was also observed. Fibrinolysis was most pronounced during the anhepatic phase of surgery and decreased after revascularization of the grafted liver. Three additional patients who underwent the same procedure manifested much less evidence of systemic fibrinolytic activation and had minimal elevation of t-PA antigen levels or activity. Urokinase-type plasminogen activator levels, although elevated in three patients, were disassociated from increased t-PA levels and concomitant systemic fibrinolysis. The operative course of those patients developing t-PA-associated fibrinolysis was characterized by shock, acidosis, generalized bleeding, and a need for substantially greater blood product support during surgery. These findings suggest that the observed fibrinolytic defect is related to increased circulating plasma levels of t-PA, presumably resulting from a combination of increased intravascular release and decreased hepatic clearance of t-PA. These observations may have implications for intraoperative therapy for the transplant-related coagulopathy and its associated bleeding.

Response of red blood cell control materials to altered testing conditions.

While many features are regularly considered in selecting control reagents, the responsiveness of these products to methodologic errors is frequently overlooked. To address this issue with regard to commercially prepared whole blood cell controls, mean cell volume (MCV) determinations were performed on several preserved red blood cell controls and fresh blood in the presence of various artifacts. The effects contaminating the isotonic diluent with water, saline, or bleach were compared. Although our results indicate that preserved and fresh RBCs generally behave similarly, large differences were observed in the responses to hypotonic stress among controls and between controls and fresh specimens. As this may have clinical relevance, our data highlight the need for testing the responsiveness of controls to commonly encountered methodologic variables as part of the routine evaluation of these products.