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Abstract:
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Risk-adjusted charting procedures which take into account patients' health conditions have been developed in the literature. One important class of risk-adjusted procedures is based on the likelihood ratio statistic obtained by testing the odds ratio of mortality. The likelihood ratio statistic essentially converts the binary outcomes of death and survival into penalty and reward scores respectively which are dependent on the predicted risk of death of a patient. For cardiac operations, the risk distribution is highly right skewed resulting in penalty scores in a narrow range for majority of the patients. This means effectively there is little risk adjustment for majority of the patients. We propose a risk-adjusted statistic which is the ratio of surgical outcome to the estimated probability of death from an operation as the monitoring statistic. The main characteristic of this statistic is that the penalty score is substantially higher if a patient with low risk dies, and the penalty score decreases sharply as the risk increases. We will compare our chart with the original risk-adjusted chart. Finally, we will demonstrate our chart with real data from two surgeons.
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