J Thorac Cardiovasc Surg 2004;128:823-825
© 2004 The American Association for Thoracic Surgery
Statistics for the Rest of Us |
Monitoring cardiac surgical performance: A commentary
Tom Treasure, MS, MD, FRCSa,*,
Stephen Gallivan, PhDb,
Chris Sherlaw-Johnson, MSc, FORSb
a Department of Thoracic Surgery, Guy's Hospital, London, UK
b Clinical Operational Research Unit, Department of Mathematics, University College, London, United Kingdom
Received for publication February 23, 2004; accepted for publication March 4, 2004.
* Address for reprints: Tom Treasure, MS, MD, FRCS, Consultant in Thoracic Surgery, Guy's Hospital, St Thomas's St, London SE1 9RT, United Kingdom
Tom.Treasure@ukgateway.net
| The first 300 words of the full text of this article appear below. |
| See related article on pages 807, 811, 820, and 907.
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Marc de Leval1 presented a cumulative sum (CUSUM) chart to The American Association for Thoracic Surgery in Chicago 10 years ago. His graph (Figure 1) showed an outstanding series of 52 cases performed with just 1 death early in the adoption of the arterial switch operation for transposition of the great arteries. The CUSUM graph concluded with a similarly excellent, nearly flat line with 1 death in the most recent 39 cases. Sandwiched between them was a cluster of deaths. de Leval's CUSUM chart was simple, explicit, and intuitive; each operation moved the graph 1 unit along the horizontal axis, and each death moved it up by 1 unit on the vertical axis. It enabled those of us fortunate to be present at what proved to be a landmark presentation to follow the story with absolute clarity. de Leval charted the results for a single procedure. Prompted by his presentation, and convinced that this method would help us display and understand our outcomes better, we worked toward a method of displaying data sequentially that would also allow for variable risk in series of different case mix. We dubbed the method variable life-adjusted display (VLAD),2 but other terms have also been used.3
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Figure 1. Cumulative failures (CUSUM) according to operative sequence (patient number) among 104 consecutive neonatal arterial switch repairs of transposition of the great arteries. Heavy solid line is CUSUM, fine solid lines are 80% alert lines, and dashed lines are 95% alarm lines. Cluster of deaths is apparent in midportion of sequence. (From de Leval MR, Francois K, Bull C, Brawn W, Spiegelhalter D. Analysis of a Cluster of Surgical Failures: Application to a Series of Neonatal Arterial Switch Operations. J Thorac Cardiovasc Surg. 1994;107:914-24).
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Copyright © 2004 by The American Association for Thoracic Surgery.