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J Thorac Cardiovasc Surg 2004;128:807-810
© 2004 The American Association for Thoracic Surgery

Statistics for the Rest of Us

Monitoring surgical performance

^a Section of Clinical Research, Department of Thoracic and Cardiovascular Surgery and Department of Biostatistics and Epidemiology, The Cleveland Clinic Foundation, Cleveland, Ohio, USA

Received for publication February 24, 2004; accepted for publication March 5, 2004.

^* Address for reprints: Eugene H. Blackstone, MD, Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk F24, Cleveland, OH 44195, USA
blackse@ccf.org

The first 300 words of the full text of this article appear below.

See related articles on pages 811, 820, 823, and 907.

 

If surgical performance—often measured by postoperative outcome of initial hospital stay—is monitored at all, the most common means is by risk-adjusted annual or semiannual audit. Observed occurrence of outcome measures (eg, in-hospital death and complications) as a proportion of cases performed is compared with expected performance using, for example, the Society of Thoracic Surgeons' regression equations¹ or EuroSCORE,² which account for many aspects of case mix. Sometimes observed (O) and expected (E) proportions are subtracted, sometimes divided (O/E ratio)³; sometimes confidence limits of these comparisons are provided, and occasionally P values are given.

Is this periodic, widespread, but rather coarse monitoring of surgical performance sufficient?

	CUSUMs—what are they and why should we care?

 
During the past year, several manuscripts have been submitted to this Journal and to The Annals of Thoracic Surgery that argue for monitoring on an individual case-after-case fashion (sequential monitoring) using the ever-expanding suite of statistical quality control techniques.⁴ The most commonly used belong to the family of cumulative sum (CUSUM) charts.⁵ These charts purport to provide early identification of deviation from a performance standard. Their forte is identifying subtle, slow, but sustained degradation in a system thought to be in control.⁴ Because early, reliable warning should be good for both patients and surgeons, the editors decided that a "Statistics for the Rest of Us" tutorial on CUSUMs would be valuable for readers.

No sooner had this decision been made than (1) Gary Grunkemeier's tutorial on CUSUMs appeared in The Annals,⁶ and (2) we received a tutorial by Rogers and colleagues⁷ from Bristol. We determined that the latter would become the centerpiece of an educational package on monitoring surgical performance, along with invited commentaries from Tom Treasure and his group from Guy's Hospital and the Clinical Operational Research Unit, . . . [Full Text of this Article]