Cusum Curves

 

This is a means of analysing a unit’s or an individual surgeon’s performance over time.

Y axis = Cumulative Deaths.
X axis = Cumulative No of operations

The Yellow line represents cumulative predicted mortality adjusted to 0.51 of the Parsonnet score. (NW Regional standard)
The Light Blue line represents cumulative observed mortality
The Pink and Dark Blue lines represent Upper and Lower 95% confidence limits of observed mortality

A unit or a Surgeon is under performing if the yellow line overlap or drop below the dark blue line

No Surgeons are under performing. We all have good years, and not so good years.
It is therefore essential that results must be looked at over a period of time, and not just over one year