Cumulative sum control charts for assessing performance in arterial surgery

Background: The Melbourne Vascular Surgical Association (Melbourne, Australia) undertakes surveillance of mortality following aortic aneurysm surgery, patency at discharge following infrainguinal bypass and stroke and death following carotid endarterectomy. Quality improvement protocol employing the Deming cycle requires that the system for performing surgery first be analysed and optimized. Then process and outcome data are collected and these data require careful analysis. There must be a mechanism so that the causes of unsatisfactory outcomes can be determined and a good feedback mechanism must exist so that good performance is acknowledged and unsatisfactory performance corrected. A simple method for analysing these data that detects changes in average outcome rates is available using cumulative sum statistical control charts. Methods: Data have been analysed both retrospectively from 1999 to 2001, and prospectively during 2002 using cumulative sum control methods. A pathway to deal with control chart signals has been developed. Results: The standard of arterial surgery in Victoria, Australia, is high. In one case a safe and satisfactory outcome was achieved by following the pathway developed by the audit committee. Conclusion: Cumulative sum control charts are a simple and effective tool for the identification of variations in performance standards in arterial surgery. The establishment of a pathway to manage problem performance is a vital part of audit activity.