BACKGROUND To simplify International Sensitivity Index (ISI) calibration, the possibility of substituting fresh plasma for fresh whole-blood samples with point-of-care testing (POCT) whole-blood monitors was investigated in a three-center study of three different POCT systems. METHODS A modified full WHO calibration procedure based on 20 healthy controls and 60 coumarin-treated patients was p...

Although the prothrombin activity was lowered, the other coagulation results were not appreciably different one week after the start of the regime of gradual withdrawal. The increase of Factor VIII concentration was still significant but less marked at the end of the second week. By the third week of the withdrawal regime the prolongation of the prothrombin time was no longer significant, altho...

The performance of coagulometers in the National Quality Assessment Scheme (NEQAS) surveys of the prothrombin time conducted between 1986 and 1987 was reviewed. There were sufficient data for analysis for eight types of coagulometer used with a single type of thromboplastin reagent and one instrument with an alternative reagent. The overall reliability efficacy of each instrument was evaluated ...

To assess the effects of oral contraceptives on anticoagulant treatment the prothrombin times of 12 patients were measured while they were taking both drugs simultaneously and while they were taking only anticoagulants. The mean prothrombin time ratio was significantly higher when patients were taking both drugs than when they were taking only anticoagulants and their doses of anticoagulant wer...

Identification of good surrogate end-points can greatly facilitate the design of clinical trials. Using data from PROWESS and ENHANCE, Shorr and colleagues explore the potential value of several plasma biomarkers for treatment trials of activated protein C for severe sepsis. Based on the framework proposed by Vasan, they tested the utility of several factors (protein C, interleukin-6, antithrom...

Treatment with warfarin using a target International Normalized Ratio (INR) range of 1.7 to 2.5 is efficacious for many clinical indications, but the minimal intensity of anticoagulation required for antithrombotic protection has yet to be determined. To evaluate whether patients could be reliably monitored with a less intense regimen, we anticoagulated patients with warfarin for several months...

A survey of physicians demonstrated that half had knowledge of the International Normalized Ratio (INR) but none used the value for monitoring their patients because it was not available from the Coagulation Laboratory. The Laboratory then provided the INR value at a physician's request. A six month review of prothrombin time (PT) results showed that only the physicians from the Cardiology Clin...

This report consists of an evaluation of a commercially available photoelectric clot timer which can be used for performing prothrombin times. In the last two years, approximately 40,000 determinations have been satisfactorily performed with this apparatus. In addition, with the use of the timer, we have been able to pick up unsuspected fibrinogen deficiencies during the course of the performan...

Fifty patients with venous thromboembolic disease being treated by heparin infusion received a three day warfarin induction regimen tailored according to the prothrombin time (British comparative ratio) measured on days 2 and 3. A prediction of the final maintenance dose of warfarin was made on the basis of a prothrombin time measured on day 4. All patients were safely anticoagulated by day 6, ...