Thromboplastin Bilbao: reproducibility and sensitivity of a Spanish thromboplastin.

Prothrombin time (PT) is the control test for oral anticoagulant therapy as well as the screening test for defects of the extrinsic pathway of coagulation. Its responsiveness to decreased extrinsic clotting factors depends on the source and type of tissue factor thromboplastin extract. In 1994, a rabbit brain thromboplastin - Thromboplastin Bilbao (TBi) - was introduced as a replacement for a human brain preparation used since 1983, with the aim of establishing a national standard. The purpose of this study was to check the reproducibility, the inter-assay/intra-assay accuracy and the stability of this reagent under temperature changes and over time. A method modified from Frei et al. [World Health Organisation Regional Publications, Eastern Mediterranean Series, Alexandria, 1995] was used for the preparation of thromboplastin extract. Thirty-five batches of human TBi were prepared from 1983 to 1988, while from 1993 to 1999 13 batches of rabbit TBi were produced. The inter-assay reproducibility of rabbit TBi exhibited a coefficient of variation (CV) of 1.07-1.57% for normal plasma and of 1.25-2.56% for anticoagulated plasma. The intra-assay CV was 0.06-1.30% for normal plasma and 1.23-2.66% for anticoagulated plasma. The stability of the reagent to temperature changes and time was also estimated, with similar results for the two thromboplastins. As a result of the Oral Anticoagulant Treatment Quality Assessment Scheme in the Basque Country, an in-house rabbit thromboplastin with good sensitivity and reproducibility was developed.

Prothrombin time quality assessment scheme in the Basque Country.

The Basque Country Quality Assessment Scheme on Oral Anticoagulant Treatment (PEEC-CAV) was first launched in 1984. This project combined prothrombin time (PT) quality controls and a new in-house standard reagent called Thromboplastin Bilbao (TBi). Originally, this reagent was of human origin, but in 1994, it was replaced by one derived from rabbit brain following WHO recommendations. Nine hospitals in the area collaborated in carrying out quality controls (a) to assess different systems of PT test performance in the Basque Country and (b) to evaluate TBi response in these controls. Evaluation over the period 1994-1999 yielded an INR coefficient of variation (CV) for the plasmas used in these controls of 8.29+/-4.18% using the laboratories' routine system (reagent and coagulometer), and 9.7+/-2.70% using TBi and the manual technique. These results were similar to those obtained in the CV of PT ratio with human brain thromboplastin from 1984 to 1988 (9.26+/-2.84%).

[Life-styles determining the oral health of adolescents in Vitoria (Gasteiz):and evaluation]. / Estilos de vida determinantes de la salud oral en adolescentes de Vitoria-Gasteiz: evaluación.

OBJECTIVE: To assess the factors determining oral health in adolescents in school at Vitoria (Gasteiz).Design. Descriptive epidemiological study. PARTICIPANTS: Randomised representative sample of 1,380 students from public and private schools. Setting. Vitoria (Gasteiz). MAIN MASUREMENTS AND RESULTS: A questionnaire on bucco-dental health was self-administered. 41.9% of the adolescents brushed their teeth three times or more a day (2.2 ( 0.98 times a day), with greater frequency in girls. 64% never used dental floss, and 30% did so only at times. 88.1% did not complement their oral hygiene with mouth-washes. Consumption of commercial cakes and pastries was 0.74 ( 1.12 times a day; and of sweets, 1.58 ( 3.15 times a day. 81.9% of the adolescents valued their mouth and dental health the same as the health of other organs of their bodies. 63.5% did not know whether any compound was added to the water as a preventive measure against dental disease; and 83.2% of those who thought something was added did not know what compound it was. 66.7% had been to the dentist during the previous year; 28.2% had not been for over a year. CONCLUSION: The oral health habits of adolescents in Vitoria (Gasteiz) show deficiencies that could be corrected through Health Education Programmes and promotion of the use of preventive dental services.

Comparative study of a portable prothrombin time monitor employing three different systems in oral anticoagulant units.

The aim of this study was to evaluate the accuracy of the portable coagulometer CoaguChek (Roche Diagnostics) as a prothrombin time (PT) monitor, and to correlate capillary blood results with those of three different routine methods used for monitoring oral anticoagulant therapy (OAT): capillary, plasma and whole blood samples. Three hospitals participated in the study with a total of 235 patients on OAT. The international normalized ratio (INR) results obtained with CoaguChek were compared with those obtained using each of the routine methods. The study presents a good correlation between the PT monitor and the three methods studied: r = 0.9745 (hospital A), r = 0.9283 (hospital B), r = 0.9136 (hospital C). A simplified concordance test of the methods results in a nine-field comparison table showing concordances of 87.2, 85.7 and 68.4%, respectively. The absolute difference (mean +/- SD) between laboratory A and CoaguChek INRs was 0.0571 +/- 0.2042, with values of 0.04286 +/- 0.3906 for laboratory B and 0.6986 +/- 0.6170 for laboratory C. These results confirm that CoaguChek could be used as a new method for oral anticoagulant monitoring, and is in best agreement with the capillary blood PT system.

[Evaluation of the quality of prothrombin time technique in the Basque Country]. / Evaluación de la calidad de la técnica del tiempo de protrombina en el País Vasco.

PURPOSE: The Programme for Quality Assessment in Anticoagulant Therapy, which was started in the Basque Country in 1984, included the manufacturing of a standard human thromboplastin reagent plus periodical quality controls of the prothrombin time. A rabbit thromboplastin reagent was available in 1994; it was called Thromboplastin Bilbao, or TBi, and had to be used as a pattern reagent. Its stability, sensitivity and composition were plotted against the Manchester Reagent, of similar nature and composition. A new phase of quality quality controls was simultaneously started with this new reagent, a group of hospitals of the Autonomous Community taking part in the programme. The aim was to compare this reagent with the others used by the hospitals and to evaluate the variations with regard to the stages previous to the introduction of the human reagent. MATERIAL AND METHODS: Nine centres joined the study. Controls were performed every fourth month including plasma from patients under anticoagulant treatment, plus the reference reagents. The partaking centres used their usual reagents and routine procedures, as well as the reference reagents and manual technique. RESULTS: The coefficient of variation (CV) of the INR of anticoagulated plasmas used for these studies when following the centres' own methods and thromboplastins was 9.5 +/- 6.40%, versus 9.94 +/- 1.57% when TBi was used. These results are in accordance with those attained with the previously manufactured human reagent, whose CV was 8.75 +/- 2.19% in the quality assurance methods performed in the period 1984-88. Concurrently with the programme, the reagent was sent as a part of the Spanish Programme for Quality Assessment in Anticoagulant Treatment to the 51 centres taking part in the study. The CV of the INR of the two lyophilized plasmas sent was, respectively, 14.97% and 16.5%. The average value for the healthy subjects was 14.77 seconds, with 8% inter-centres variation when using manual methods. CONCLUSIONS: These results suggest that a thromboplastin is now available whose sensitivity and reproducibility make it suitable as the national standard for usage in the quality assessment of prothrombin time.

Comparative study of a portable monitor for prothrombin time determination, Coaguchek, with three systems for control of oral anticoagulant treatment.

Self-testing of oral anticoagulation is a new possibility related to the development of portable capillary whole blood prothrombin time monitors. The aim of this study was to evaluate one of this monitors, Coaguchek, with respect to its comparability with our routine prothrombin time determination system, as well as with the reference manual technique and two thromboplastins of high sensitivity, Manchester Reagent and one manufactured in our center, Thromboplastin Bilbao, in a group of patients on oral anticoagulant treatment. Although a correlation of r = 0.9271 was found between international normalized ratio (INR) values of Coaguchek and our routine method, Neoplastine/STA analyzer, the difference of the INR scatter increased with the magnitude of measurement, being lowest for INR between the portable monitor and Manchester Reagent and Thromboplastin Bilbao, with a similar coefficient of correlation, r = 0.8948 and r = 0.8905, respectively. A test was performed showing a 65.6% agreement with the INR values of the STA analyzer, 66.4% with Manchester Reagent and 73.4% with Thromboplastin Bilbao. On the basis of this correspondence with laboratory prothrombin time results Coaguchek may be considered as a possible option for monitoring anticoagulated patients even though patients should be given instructions and advice as regards the management and interpretation of the results.