Download PDF
Thromb Haemost 1985; 54(03): 704-708
DOI: 10.1055/s-0038-1660102
Original Article
Schattauer GmbH Stuttgart

Prothrombin Time Proficiency Testing: A Robust Grading Method

Yangsook Han
The Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany, New York, USA
,
William B Lawson
The Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany, New York, USA
,
W Jean Dodds
The Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany, New York, USA
,
Charles E Lawrence
The Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany, New York, USA
› Author Affiliations
Further Information

Publication History

Received 28 May 1985

Accepted 27 August 1985

Publication Date:
19 July 2018 (online)

  PDF Download  Permissions and Reprints

Summary

A robust two-way analysis of variance technique was applied to determine simultaneously the effects of method and thromboplastin on prothrombin time. A new approach to outlier detection for two-way analysis of variance was used. Focusing on the underlying error structure improved the uniformity of the grading procedure in the hematology proficiency testing program of the New York State Department of Health.

The logarithm-transformed scale produced constancy of error variance and resulted in uniformity of the acceptable spread of data. The common variance was lower than that obtained by previous methods and allowed for a narrower acceptable range of reported prothrombin times by reducing the inflated standard deviation, thus improving the efficiency of the grading procedure.

For proficiency testing, no advantage was found in the use of either a common thromboplastin or freeze-dried, coumadinized patient plasmas rather than artificially depleted commercial plasmas, except for special purposes.

Keywords

Proficiency testing - Robust estimation - Outliers - Prothrombin time - Instrumentation - thromboplastin variables
 

  • References

  • 1 Loeliger EA, van Dijk-Wierda CA, van den Besselaar AM H P, Broekmans AW, Roos J. Anticoagulant control and the risk of bleeding. In: Anticoagulants and myocardial infarction A reappraisal. Meade TW. (Ed). John Wiley; New York: 1984: 135-177
  • 2 Biggs R, Denson KW E. Standardization of the one-stage prothrombin time for the control of anticoagulant therapy. Br Med J 1967; 1: 84-90
    CrossrefPubMedGoogle Scholar
  • 3 Ingram GI C, Hills M. Reference method for the one-stage prothrombin time test on human blood. Thromb Haemostas 1976; 36: 237-238
    PubMedGoogle Scholar
  • 4 Loeliger EA, van Dijk-Wierda CA, Ross J. Quality control and standardization of the prothrombin time. Second International Symposium on Quality Control. Tokyo, Japan 1976
    PubMedGoogle Scholar
  • 5 Poller L. The British system for anticoagulant control. Thrombos Diathes Haemorrh 1975; 33: 32-50
    PubMedGoogle Scholar
  • 6 Hermans J, van den Besselaar AM H P, Loeliger EA, van der Velde EA. A collaborative study of reference materials for thromboplastins. Thromb Haemostas 1983; 50: 712-717
    PubMedGoogle Scholar
  • 7 Van den Besselaar AM H P, Gralnick HR, Lewis SM. (Eds). Thromboplastin Calibration and Oral Anticoagulant Control. Mar-tinus Nijhoff; Boston: 1984
  • 8 Evatt BL, Brogan D, Triplett D, Koepke J, Waters G. Effect of thromboplastin and instrumentation on the prothrombin time test. Clin Lab Haematol 1981; 3: 331-342
    PubMedGoogle Scholar
  • 9 Triplett DA, Evatt BL, van den Besselaar AM H P. Proficiency testing and standardization of prothrombin time - potential use of thromboplastin calibration in the United States. In: Ref. 7 209-221
    PubMedGoogle Scholar
  • 10 van den Besselaar AM H P, Evatt BL, Brogan DR, Triplett DA. Proficiency testing and standardization of prothrombin time: Effect of thromboplastin instrumentation and plasma. Am J Clin Pathol 1984; 82: 688-699
    CrossrefPubMedGoogle Scholar
  • 11 Kendall M, Stuart A. The advanced theory of statistics 1976; 3: 30
    PubMed
  • 12 Kim JO, Kohout FJ. Analysis of variance and covariance: subprograms ANOVA and one-way. In: Nie NH, Hull CH, Jenkins JF, Stein-Brenner K, Bent DH. (Eds). Statistical Package for the Social Sciences. McGraw-Hill; New York: 1975. 2nd ed: 398-433
  • 13 Paulson AS, Delehanty TA. Sensitive analysis in experimental design. In: Heiner KW, Sacher RS, Wilkinson JW. (Eds). Computer Science and Statistics: Proceedings of the 14th Symposium on the Interface. Springer-Verlag; New York: 1982: 51-57
  • 14 Paulson AS, Nicklin EH. Integrated distance estimators for linear models applied to some published data sets. Appl Statist 1983; 32: 32-50
    CrossrefPubMedGoogle Scholar
  • 15 Daniel C. Patterns in Residuals in the Two-Way Layout. Technometrics 1978; 20: 385-396
    CrossrefPubMedGoogle Scholar
  • 16 Gentleman JF, Wilk MB. Detecting Outliers in a Two-way Table: I Statistical Behavior of Residuals. Technometrics 1975; 12: 1-14
    PubMedGoogle Scholar
  • 17 Winer BJ. Statistical Principles in Experimental Design. McGraw-Hill, New York 1971 2nd Ed: 564
    PubMedGoogle Scholar
  • 18 Levene H. Robust tests for equality of variance. In: Olkin I. (ed). Contributions to Probability and Statistics. Stanford Univ Press; Palo Alto, CA: 1960: 278-292
  • 19 Anderson TW, Darling DA. A test of goodness of fit. J Am Statist Assoc 1954; 49: 765-769
    CrossrefPubMedGoogle Scholar
  • 20 College of American Pathologists: 1985 Manual, CAP Surveys, Section II, Hematology-Coagulation Clinical Microscopy. College of American Pathologists, Skokie, Illinois 1985: 9-10
    PubMedGoogle Scholar
  • 21 Lindgren BW. Statistical Theory. MacMillan Co.; New York: 1962: 89
  • 22 Sherwood GE F, Taylor AE. Calculus. Prentice-Hall, Englewood Cliffs, NJ 1954 3rd Ed 391
    PubMedGoogle Scholar