MONITORING THE RESULTS OF CARDIAC-SURGERY BY VARIABLE LIFE-ADJUSTED DISPLAY

Background Conventional assessment of the outcome of cardiac surgery u sually takes the form of retrospective mortality figures and, at best, indicates an average performance over time. Summary tables conceal go od and bad runs, and without risk adjustment they are difficult to int erpret. We developed a refinement of the cumulative sum method that we ights death and survival by each patient's risk status and provides a display of surgical performance over time. Methods The variable life-a djusted (VLAD) plot shows the difference between expected and actual c umulative mortality. VLAD shows whether a surgeon's performance is abo ve or below what might be expected. This mortality-scoring system accu mulates penalties for each death and rewards for every survivor, based on the inherent risk of perioperative death of each case concerned. F indings We illustrate the results of three performance reviews, displa yed as VLADs. The first shows the results of an individual surgeon for 547 consecutive cardiac-surgical cases. The overall mortality was 36% less than that predicted by the Parsonnet scoring system. The second displays the results for 5000 consecutive patients who underwent cardi opulmonary bypass between 1992 and 1996, divided into six contemporane ous series. The predicted mortality was 9% compared with 6% actual mor tality. The third is a plot for a trainee surgeon and clearly shows ho w a period of poor performance was identified and then substantially i mproved, which would not have been revealed by conventional tables of summary statistics. Interpretation VLAD provides a graphical display o f risk adjusted survival figures for individual surgeons or units over time and could be modified to monitor performance over a range of tre atments and outcomes.