Control chart methods for monitoring surgical performance: a case study from gastro-oesophageal surgery.

Graphical methods are becoming increasingly used to monitor adverse outcomes from surgical interventions. However, uptake of such methods has largely been in the area of cardiothoracic surgery or in transplants with relatively little impact made in surgical oncology. A number of the more commonly used graphical methods including the Cumulative Mortality plot, Variable Life-Adjusted Display, Cumulative Sum (CUSUM) and funnel plots will be described. Accounting for heterogeneity in case-mix will be discussed and how ignoring case-mix can have considerable consequences. All methods will be illustrated using data from the Scottish Audit of Gastro-Oesophageal Cancer services (SAGOCS) data set.