Comparison between Recombinant and Rabbit Thromboplastin in the Management of Patients on Oral Anticoagulant Therapy

Summary

The aim of this study was to compare recombinant thromboplastin (rTF, ISI = 0.82) with rabbit thromboplastin (RT, ISI = 1.46) in order to evaluate which performed better in our thrombosis centre. To this purpose we randomized 67 patients to be double-blind monitored in two groups for three months either with PT performed with RT or with PT performed with rTF. After this period each patient was shifted to the other group. We considered the following as end points of the study: percentages of PT results within the therapeutic range, number of visits and therapeutic dose adjustments per patient. The “last check in file” method was used to evaluate the laboratory quality of oral anticoagulation for both thromboplastins. The results show that there was no difference in the number of visits per patient between the two groups: 6.9 ± 1.7 in the rTF group versus 7.3 ± 1.9 in the RT group (p = 0.19). The variations of therapeutic dose per patient were not different in the two groups: the dose was changed once (range 0-8) in the rTF group and once (range 0-11) in the RT group (p = 0.15). The percentages of PT results within the therapeutic range were not different between the two groups. The “last check in file” method showed similar percentages in both groups: PT results in the therapeutic range were 67.2% in the RT group and 68.8% in the rTF group. We conclude that the two thromboplastins had a similar effect on the end points of the study in spite of the relatively high ISI of the RT.

• References

• 1 Loeliger EA. Laboratory control, optimal therapeutic ranges and therapeutic quality control in oral anticoagulation. Acta Haematol 1985; 74: 125-131
• 2 Tripodi A, Chantarangkul V, Braga M, Poller L, ten Cate JW, van den Besselaar AMPH, Mannucci PM. Results of a multicenter study assessing the status of standardization of a recombinant thromboplastin for the control of oral anticoagulant therapy. Thromb Haemost 1994; 72: 261-267
• 3 Roussi J, Drouet L, Samama M, Sié P. French multicentric evaluation of recombinant tissue factor (Recombiplastin) for determination of prothrombin time. Thromb Haemost 1994; 72: 698-704
• 4 Manotti C, Quintavalla R, Pattacini C, Pini M. Seasonal variation of oral anticoagulant effect. Thromb Haemost 1994; 71: 802-803
• 5 Machin D, Campbell MJ. Statistical tables for design of clinical trials. Blackwell Scientific Publication, London 1987
• 6 Pocock SJ. Clinical trials - a practical approach. John Wiley & Sons Ltd, London 1983
• 7 van den Besselaar AMPH, van der Meer FJM, Gerrits-Drabbe CW. Therapeutic control of oral anticoagulant treatment in the Netherlands. Am J Clin Pathol 1988; 90: 685-690
• 8 Poller L, Tabemer DA, Thomson JM, Darby KV. Survey of the prothrombin time in National External Quality Assessment Scheme Exercise (1980-87). J Clin Pathol 1988; 41: 361-364
• 9 Finazzi G, Falanga A, Galli M, Cortellazzo S, Remuzzi A, Barbui T. Recombinant versus high-sensitivity conventional thromboplastin: a randomized clinical study in patients on oral anticoagulation. Thromb Haemost 1994; 72: 804-807