Thorac Cardiovasc Surg 2000; 48(2): 72-78
DOI: 10.1055/s-2000-9869
Original Cardiovascular
© Georg Thieme Verlag Stuttgart · New York

Target, Application, and Interpretation of Scores and Alternative Methods for Risk Assessment in Cardiac Surgery[1]

B. R. Osswald, U. Tochtermann, P. Schweiger, G. Thomas, D. Göhring, C. F. Vahl, S. Hagl
  • Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany
Further Information

Publication History

January 20, 2000

Publication Date:
31 December 2000 (online)

Background: The more popular the use of different methods for risk adjustment becomes, the more often data are applied without any regard about the primary target and/or about important assumptions. Furthermore, risk adjustment is no longer restricted for quality assurance purposes, but became a “tool” of health policy. Few working groups currently use risk adjustment for the development of new therapeutic concepts. The aim of our study is to clarify possibilities and limitations of popular risk adjustment methods. Patients and Methods: 4985 Patients underwent isolated CABG. Statistics was performed by calculating descriptive statistics, Parsonnet, and Higginsscores. Furthermore, the parametric, time-adjusted hazard function by Blackstone was used. Results: Descriptive statistics allows intra-, and interinstitutional comparisons of single items to identify “outlying” results. Risk scores aim to predict preoperatively the risk category of the patient who undergoes cardiac surgery. However, since different scores are based on a score-specific combination of variables, and different definitions of the investigation interval, different results may occur, when different scores are calculated for a single patient. However, the use for example, of scores in patient groups allows description of changing risk structures. Most of the scores derive from univariate analyses and monophasic functions. However, survival curves are predominantly multiphasic and require a consideration of the time-dependency of “risk factors”. Discussion: An increasing number of patients with severe comorbidity undergoes cardiac surgery. To evaluate reliably present and futurous therapeutic options, risk adjustment is necessary. Since various tools for risk-adjustment are available, a serious discussion about reliability and application is necessary.

1 Presented at the International Congress on “Risk Stratification in Cardiac and Thoracic Surgery”, October 15/16, 1999, Cologne, Germany.

References

  • 1 Parsonnet V, Dean D, Bernstein A D. A method of uniform stratification of risk for evaluating the results of surgery in acquired adult heart disease.  Circulation.. 1989;  79 (Suppl. 1) I3-I12
  • 2 Higgins T L, Estafanous F G, Loop F D, Beck G J, Blum J M, Paranandi L. Stratification of Morbidity and Mortality Outcome by Preoperative Risk Factors in Coronary Artery Bypass Patients.  JAMA.. 1992;  267 2344-8
  • 3 The New Jersey Open Heart Surgery Database. http://www.state.nj.us/health/hcsa/cabgs98/cabgs98.htm 1996 - 1997
  • 4 Blackstone E H, Naftel D C, Turner M E Jr. The decomposition of time-varying hazard into phases, each incorporating a separate stream of concomitant information.  J Am Stat Assoc.. 1986;  81 615-24
  • 5 Vahl C F, Tochtermann U, Gams E, Hagl S. Efficiency of a computer network in the administrative and medical field of cardiac surgery. Concept and experiences with a departmental system.  Eur J Cardiothorac Surg.. 1990;  4 632-8
  • 6 Vahl C F, Herold U, Thomas G, Tochtermann U, Schweiger P, Carl I, Hagl S. HVMD Study Group .Das “Heidelberger Modell”. In: Krian A, Scheld HH (eds) Dokumentationsverfahren in der Herzchirurgie. Steinkopff Verlag Darmstadt; 35-52
  • 7 Kaplan E, Meier P. Non-parametric estimation from incomplete observations.  J Am Stat Assoc.. 1958;  53 457-4811
  • 8 Cox D R. Regression models and life tables.  J.R. Stat Soc B.. 1972;  Ser B 34 187-202
  • 9 Vahl C F, Carl I, Meinzer H P, Thomas G, Hagl S. Eichung klinischer Datenbanken mit “virtuellen Patienten”.  Z Kardiol.. 1995;  86 35-41
  • 10 Struck E, Rupp G, Huber W, Chryssagis G. Defizite der Primärdaten. In: Krian A, Scheld HH (eds) Dokumentation in der Herzchirurgie. Steinkopff Verlag 93-100
  • 11 Kalmar P. Quality assurance in cardiac surgery: history, preliminaries, practical experience.  Thorac Cardiovasc Surg.. 1990;  38 108-14
  • 12 Struck E, DeVivie E R, Hehrlein F, Hügel W, Kalmar P, Sebening F, Wilde E. Multicentric quality assurance in cardiac surgery. QUADRA study of the German Society for Thoracic and Cardiovascular Surgery.  Thorac Cardiovasc Surg.. 1990;  38 123-34
  • 13 Wilde W, Christof K, Struck E. Development and application of a quality assurance information system in cardiac surgery (QUADRA study).  Thorac Cardiovasc Surg.. 1990;  38 115-22
  • 14 Osswald B R, Tochtermann U, Thomas G, Vahl C F, Hagl S. Influence of follow-up response on risk-factor analysis.  Thorac Cardiovasc Surg.. 1999;  47 32-7
  • 15 Osswald B R, Blackstone E H, Tochtermann U, Thomas G, Vahl C F, Hagl S. The meaning of early mortality after coronary artery bypass surgery.  Eur J Cardiothorac Surgery.. 1999;  15 401-7
  • 16 Blackstone E H. Outcome analysis using hazard function methodology.  Ann Thorac Surg.. 1996;  61 S2-7
  • 17 Blackstone E H. Born of necessity: the dynamic synergism between advancement of analytic methods and generation of new knowledge.  J Heart Valve Dis.. 1995;  4 326-36
  • 18 Blackstone E H, Kirklin J W. Recommendations for Prophylactic Removal of Heart Valve prostheses.  J Heart Valve Dis.. 1992;  1 3-14
  • 19 Kirklin J W, Barratt-Boyes B G. The generation of knowledge from information, data, and analyses.  In: Kirklin JW, Barratt-Boyes BG (eds.) Cardiac Surgery.  2nd edition. Churchill Livingstone New York, Edinburgh, London, Melbourne, Tokyo; 1993
  • 20 Osswald B R, Vahl C F, Hagl S. Increase of “high risk patients” undergoing CABG?.  CVE.. 1997;  2 228-30

1 Presented at the International Congress on “Risk Stratification in Cardiac and Thoracic Surgery”, October 15/16, 1999, Cologne, Germany.

Dr. med. Brigitte R. Osswald

Department of Cardiac Surgery University of Heidelberg

Im Neuenheimer Feld 110 69120 Heidelberg Germany

Phone: Phone: #49 / 6221 / 56-6111

Fax: Fax: #49 / 6221 / 56-5585

Email: E-mail: brigitte_osswald@med.uni-heidelberg.de