The need for an adapted initiation nomogram during Fiix prothrombin time monitoring of warfarin

Journal of Thrombosis and Thrombolysis - The new Fiix prothrombin time (Fiix-PT) and its derived Fiix-normalized ratio (Fiix-NR) is affected only by reductions in coagulation factors (F) II and X,...     

Randomized prospective trial comparing the native prothrombin antigen with the prothrombin time for monitoring oral anticoagulant therapy

The dosage of the anticoagulant warfarin sodium is based upon the prolongation of the prothrombin time into an optimal therapeutic range. We have developed a new assay for the native prothrombin antigen that measures the fully gamma-carboxylated prothrombin using a radioimmunoassay. Based on preliminary data that indicated that the native prothrombin antigen predicted both bleeding and thrombotic complications more accurately than the prothrombin time in patients anticoagulated with warfarin sodium, we have performed a randomized prospective trial comparing the complication rate in warfarin-treated patients monitored with the native prothrombin antigen or the prothrombin time. Patients with indications for anticoagulation were randomized to be monitored by the native prothrombin antigen (therapeutic range, 12 to 24 micrograms/mL) or the prothrombin time index (therapeutic range, 1.5 to 2.0). Of the prothrombin time group (N = 80), seven (8.8%) had bleeding or thrombotic complications, with a complication rate of 9.5%/patient-year. In the native prothrombin antigen group (N = 76), one subject (1.3%) had a bleeding complication. The complication rate per patient-year was 1.5%. These results indicate an 85% reduction in the complication rate of the native prothrombin antigen group compared with the complication rate of the prothrombin time group. This difference is statistically significant by the Fisher exact test (P = .037) and by Kaplan Meier survival analysis (P = .040). This study suggests that the use of the native prothrombin antigen assay has the potential to decrease the complications associated with anticoagulation therapy with warfarin sodium.     

Home prothrombin time monitoring: a literature analysis

The anticoagulant activity of warfarin sodium is monitored by the prothrombin time (PT) using the international normalized ratio (INR). Standard oral anticoagulant therapy monitoring requires frequent patient visits to physicians' offices and/or laboratories to optimize warfarin dosage. Home PT monitoring by patients can increase testing frequency and may thus decrease complications associated with oral anticoagulant therapy. Clinical studies suggest that home PT monitoring is more effective than uncoordinated management and is as effective as care through specialized anticoagulation clinics for keeping INRs within a therapeutic range. There are accurate and reliable instruments available, but paramount to the success of home PT monitoring is sound patient selection, appropriate patient training, and consistent quality control.     

Comparison of the native prothrombin antigen and the prothrombin time for monitoring oral anticoagulant therapy

We have measured the fully carboxylated (native) prothrombin antigen and the undercarboxylated (abnormal) prothrombin antigen in patients treated with sodium warfarin using specific immunoassays to evaluate a new approach for monitoring oral anticoagulant therapy. Plasma and serum samples (391) were assayed for the prothrombin time, native prothrombin antigen, and abnormal prothrombin antigen. The results were correlated with the presence of bleeding or thromboembolic complications at the time of phlebotomy. The native prothrombin antigen correlated with the occurrence of complications in 95% of samples. Of 13 samples from patients with bleeding complications, 13/13 (100%) had a native prothrombin of 12 micrograms/mL or lower. Of seven samples from patients with thromboembolic complications, 6/7 (86%) had a native prothrombin of 24 micrograms/mL or greater. By comparison, a prothrombin time index of 1.5 to 2.5, 1.5 to 2.2, 1.5 to 2.0, or 1.3 to 1.8 identified 6/20 (30%), 9/20 (45%), 11/20 (55%), or 12/20 (60%) patients at risk, respectively. Although the prothrombin time index did correlate with the presence of bleeding complications, the native prothrombin antigen correlated closely with the presence of bleeding and thromboembolic complications. According to these results, the native prothrombin antigen, maintained in a range of 12 to 24 micrograms/mL by regular adjustment of the warfarin dosage, may be associated with a reduced risk of complications due to excessive or insufficient warfarin therapy. On the basis of these preliminary data, we recommend that the native prothrombin antigen be considered to monitor warfarin therapy.     

Heparin therapy: A randomized prospective study

Eighty patients were assigned randomly either to continuous or to intermittent heparin therapy, with control by the Lee-White Clotting Time (LWCT). Major bleeding complications occurred in 7.5 per cent and minor complications in 18 per cent of the entire group. The incidence of major bleeding complications in the continuous group (5 per cent) did not differ significantly from the incidence in the intermittent group (10 per cent). In contrast, bleeding complications were significantly more frequent in patients with soft-tissue trauma due to such procedures as thoracenteses and cut-downs, vascular damage due to other causes, and LWCTs over 35 minutes for 2 consecutive days.The incidence of bleeding complications appear to be the same in patients receiving intermittent as in those receiving continuous heparin therapy. Thoracenteses, cut-downs, and other forms of soft-tissue injury predispose to bleeding complications while laboratory monitoring with the LWCT may help to reduce bleeding complications.     

Complications of warfarin therapy monitored by the international normalized ratio versus the prothrombin time ratio

The objective of our study was to determine the rates of bleeding complications and thromboembolic events in patients receiving oral anticoagulant therapy monitored with the prothrombin time (PT) ratio versus therapy monitored with the International Normalized Ratio (INR) using a retrospective time-series study design. Over 650 patients enrolled in a large anticoagulation clinic were studied during two time periods corresponding to the use of the PT ratio versus the INR to guide anticoagulant therapy, with over 400 patient-years of follow-up for each time period. The rate of bleeding complications using the PT ratio to guide therapy was 6.7% (1.2% major, 5.5% minor) per patient-year, compared with 2.9% (0% major, 2.9% minor) using the INR (p = 0.02). The rate of thromboembolic complications was 1.0% using the PT ratio, compared with 0.2% using the INR (p = NS). Therapy monitored with the INR required 19.8 visits per year, compared with 20.7 visits per year using the PT ratio. We conclude that the INR should be used to monitor oral anticoagulant therapy in an effort to reduce bleeding complications while maintaining an acceptable rate of thromboembolic events.     

Laboratory control of continuous intravenous heparin therapy with Howel time and activated partial thromboplastin time. A prospective, randomized and blind study

Although heparin has been used extensively to treat Deep Venous Thrombosis (DVT) and arterial ischemia (AI), controversy still exists regarding optimal dosage and the need for monitoring. Different authors have employed various test with variable results. Others, however, persist in giving heparin without laboratory control. This study was made in order to compare, in a prospective, randomized and blind manner, two coagulation tests, namely: Howel Time (HT) and Activated Partial Thromboplastin Time (APTT), in controlling the dose of heparin given by continuous intravenous infusion in DVT and AI. Our results show no significant difference in complications and failures of the therapy with either test, although significantly higher doses of heparin were needed to maintain APTT within therapeutic range than those needed to keep HT within a similar range.     

Analysis of warfarin therapy in pediatric patients: A prospective cohort study of 319 patients.

This study details warfarin use in a large pediatric population followed in a central anticoagulation clinic. A prospective, consecutive cohort of nonselected children were studied. Patients were divided into groups by age, target international normalized ratio (INR) range, disease, medications, and vitamin K supplemented enteral nutrition use. Groups were analyzed on multiple aspects of warfarin therapy using multivariate methods. A total of 319 patients received 352 warfarin courses representing 391 treatment years. Age independently influenced all aspects of therapy. When compared with all older children, the 相似文献   

Potential dosing errors using portable prothrombin time monitoring devices.

Portable prothrombin time (PT) monitors facilitate the control of warfarin therapy. Few studies have compared the influence of using different monitors on dosage decisions. We determined the comparability of data generated by two portable PT monitors, Coaguchek S, (Roche Diagnostics Boehringer-Mannheim) and Hemochron Jr (International Technidyne Corporation Ltd.), with that of a reference laboratory. Simultaneous International Normalized Ratio (INR) measurements (portable monitor and laboratory) were performed in 193 consecutive patients receiving warfarin for at least 3 months. Agreement of measurements was assessed by both regression analysis and influence on dosage decisions in accordance with pre-defined criteria. The Coaguchek S versus laboratory INR regression line (n = 111; r2 = 0.88; P < 0.001) was close to the line of identity, while that of the Hemochron Jr (n = 82; r2 = 0.61; P < 0.001) was not. The overall proportion of dual INR measurements that fulfilled the clinical criteria of agreement was 90% for the Coaguchek S compared with 62% for the Hemochron Jr (P < 0.0001). For laboratory INRs 2.0-2.5, 2.6-4.0 and > 4.0, the proportions of portable measurements that satisfied the clinical criteria for the Coaguchek S versus the Hemochron Jr were 96 versus 63% (P < 0.001), 81 versus 45% (P < 0.04), and 67 versus 17% (P < 0.85), respectively. Warfarin dosing based solely on the portable devices would have resulted in unjustified dose increments in 22% of the patients with the Hemochron Jr device compared with 8% with the Coaguchek S monitor (chi2 = 4.43; P = 0.035). The Coaguchek S monitor provides measurements for INR values within the therapeutic range that agree well with the standard laboratory. The Hemochron Jr measurements result in different dosage adjustments even within the therapeutic range, but especially for INR values > 4.0. For both monitors, agreement of INR measurements with the standard decreases with increasing INR values.     

A necrotic skin lesion in a dialysis patient after the initiation of warfarin therapy: a difficult diagnosis

Necrotic skin lesions are unfortunately common in patients with end stage renal disease undergoing dialysis therapy. We present a case of a necrotic skin lesion in a peritoneal dialysis patient shortly after the initiation of warfarin therapy for atrial fibrillation. We discuss and contrast distinguishing features of two diagnostic possibilities: warfarin skin necrosis (WSN) and calcific uremic arteriopathy (CUA) in terms of clinical presentation, risk factors and pathology. Lastly, we outline the importance of establishing a diagnosis as treatment regimens differ substantially.     

Laboratory monitoring of warfarin therapy in Utah

Accurate laboratory monitoring of oral anticoagulation has been emphasized as an important factor in providing safe and effective therapy for patients with thromboembolism. However, recent reports indicate that coagulation laboratories may not be providing optimal clinical information to clinicians who treat these patients. We surveyed all hospltal coagulation laboratories in Utah to determine their format for reporting prothrombin time results in patients receiving oral anticoagulants. We found that less than 50% of laboratories used the reliable reporting format, i.e., the interational Normalized Ratio (INR), and that many of the laboratories using the INR format may be reporting incorrect values. Our survey also found a significant lack of interest by physicians in requesting that their laboratories adopt reliable reporting methods. These results indicate a substantial lack of understanding by laboratories and clinicians of the importance of using reliable methods to monitor oral anticoagulation. Significant educational efforts will be required to correct this problem. © 1994 Wiley-Liss, Inc.     

A prospective, randomized study of empirical antifungal therapy for the treatment of chemotherapy-induced febrile neutropenia in children

Given that the rationale for empirical antifungal therapy in neutropenic children is limited and based on adult patient data, we performed a prospective, randomized, controlled trial that evaluated 110 neutropenic children with persistent fever. Those at high risk for invasive fungal infections (IFI) received caspofungin (Arm C) or liposomal amphotericinB (Arm B); those with a lower risk were randomized to receive Arm B, C, or no antifungal treatment (Arm A). Complete response to empirical antifungal therapy was achieved in 90/104 patients (86·5%): 48/56 at high risk (85·7%) [88·0% in Arm B; 83·9% in Arm C (P = 0·72)], and 42/48 at low risk (87·5%) [87·5% in control Arm A, 80·0% Arm B, 94·1% Arm C; (P = 0·41)]. None of the variables tested by multiple logistic regression analysis showed a significant effect on the probability to achieve complete response. IFI was diagnosed in nine patients (8·2%, 95% confidence interval, 3·8-15·0). This randomized controlled study showed that empirical antifungal therapy was of no advantage in terms of survival without fever and IFI in patients aged <18 years and defined with low risk of IFI. Higher risk patients, including those with relapsed cancer, appear to be the target for empirical antifungal therapy during protracted febrile neutropenia.     

Midazolam for patients undergoing upper gastrointestinal endoscopy: a prospective, single-blind and randomized study to determine the appropriate amount and time of initiation of endoscopy

BACKGROUND AND AIMS: Midazolam is currently the most used sedative agent in endoscopy. The present study was designed to examine the appropriate dose of midazolam, time of initiation of endoscopy after midazolam infusion, and to prove the necessity of flumazenil as an antidote. METHODS: One hundred and eighty patients undergoing diagnostic gastroscopy were assigned three different amounts of intravenous midazolam in prospective, single-blinded and randomized setting as follows: (i) group I 0.03 mg/kg midazolam; (ii) group II 0.06 mg/kg midazolam; and (iii) group III 0.09 mg/kg midazolam. Endoscopy was initiated 30, 60 and 90 s after infusion of midazolam within each group. After endoscopy, patients were divided into two groups, one receiving flumazenil and one placebo in a double-blind fashion. The ease of the procedure, the conscious sedative state, the paradoxical response, the level of satisfaction and anterograde amnesia were assessed using a 100 mm visual analog scale. RESULTS: The endoscopist's assessments were not changed by the different doses of midazolam; however, significant differences were observed in the paradoxical responses (P < 0.05). The level of satisfaction with endoscopy was notably different between group I and the other two groups (P < 0.05). Amnesia was boosted according with increasing doses of midazolam (P < 0.05). The time until discharge after endoscopy was significantly different between group III and the other two groups (P < 0.05) and the discharge time was reduced in the flumazenil subgroup compared with the placebo subgroup in group III (P < 0.05). Group II (0.06 mg/kg) reported good levels of satisfaction, fewer paradoxical responses and short discharge time without any side-effects. Comparing the time of initiation of endoscopy (at 30, 60 and 90 s after midazolam) in each group, there were no significant differences in the level of satisfaction, conscious sedative state and amnesia. CONCLUSIONS: Midazolam should be administered at a dose of 0.06 mg/kg and the endoscopy should be initiated 30 s after midazolam injection for appropriate effects without any side-effects. Flumazenil is not necessary, except in the case of the use of a high dose (above 0.09 mg/kg) of midazolam.     

A prospective, randomized study of endometrial telomerase during the menstrual cycle

The purpose of this study was to characterize telomerase activity during the menstrual cycle, focusing on the luteal phase. A total of 84 endometrial biopsy samples were obtained from 72 participants. Daily urinary LH testing (OvuQuick, Quidel) was used to establish the day of the LH rise, and participants were randomized to return during the secretory phase. Twelve women returned on the identical day during the luteal phase of a subsequent cycle to allow intercycle comparisons of telomerase activity. Telomerase activity was evaluated using a modified TRAP-eze (Intergen) detection protocol. At the time of each endometrial biopsy, serum estrogen and progesterone were measured. Proliferative phase endometrium showed high telomerase activity. At the onset of the luteal phase telomerase activity was high, but it decreased during the early luteal phase, disappeared by the midluteal phase (6 d after LH surge detected), and then rose to moderate levels in the late luteal phase beginning on luteal d 10. Serum progesterone levels were inversely related to telomerase activity. In conclusion, endometrial telomerase activity is dynamic: high during the proliferative phase but inhibited during the midsecretory phase of the menstrual cycle. The timing of expression coincides with the rise and fall of progesterone levels and the time period of maximal uterine receptivity for embryo implantation. This supports a relationship between sex steroid levels and telomerase regulation.