Likely variations in perioperative mortality associated with cardiac surgery: when does high mortality reflect bad practice?. Issue 1 (1st July 2000)

• Record Type: Journal Article
• Authors: Sherlaw-Johnson, C; Lovegrove, J; Treasure, T; Gallivan, S
• Is Part Of: Heart. Volume 84:Issue 1(2000)
• Page Start: 79
• Page End: 82
• Publication Date: 2000-07-01
• Subjects: perioperative mortality -- variable life adjusted display -- locally derived risk score -- Parsonnet score; Heart -- Diseases -- Treatment -- Periodicals; Cardiology -- Periodicals; 616.12
• DOI: 10.1136/heart.84.1.79
• Languages: English
• ISSNs: 1355-6037

Abstract

Abstract : OBJECTIVE: Several methods exist for estimating the risk of perioperative mortality based on preoperative risk factors; graphical methods such as the variable life adjusted display (VLAD) can be used to examine how an individual surgeon's performance for a series of operations fares against what would be expected, given the case mix. This study aimed to devise a method for assessing the natural variation in outcome in order to assist with making judgements about individual performance, in particular whether seemingly poor performance could have occurred by chance. METHOD: The risk scoring system has been derived and validated locally for cardiac surgery. A method is described for calculating the probability that an observed number of deaths occurs within a sequence of operations if perioperative mortality is regarded as a chance event with an expected value derived from the risk score. To illustrate this method, nested prediction intervals are superimposed onto VLAD plots for a series of 393 isolated coronary artery bypass and isolated valve operations performed by a single surgeon. RESULTS: Using the locally derived risk score, the VLAD plot for the individual surgeon shows a net life gain of about 6 over the predicted number of survivors, which is observed to be within the 90% prediction interval. If the Parsonnet scoring system is used instead of the locally derived risk score, the net life gain is considerably overestimated. CONCLUSIONS: The nested prediction intervals are straightforward to generate and can be integrated into a visually informative display. As an indication of the inherent variability in outcome, they have a valuable role in the monitoring of surgical performance.