Phase I risk-adjusted control charts for surgical data with ordinal outcomes

ABSTRACT

In recent years, risk-adjusted control charts that account for the preoperative risk of patients have been widely used for monitoring of surgical outcomes. Generally, risk-adjusted control charts have been developed on the basis of a binary classification of surgical outcomes. However, for a patient who survives an operation, it is reasonable to consider different grades of recovery in an ordinal manner. On the other hand, Phase I monitoring of risk-adjusted control charts has been neglected. Hence, in this paper, a general Phase I risk-adjusted control chart is proposed to monitor ordinal outcomes of surgical outcomes. The proposed risk-adjusted model is developed on the basis of proportional odds logistic regression models. The application of the proposed model is illustrated by analyzing the data in a case study and its performance is evaluated using a Monte Carlo simulation study.

KEYWORDS:

• Risk-adjusted control charts
• surgical outcomes
• proportional odds logistic regression
• cumulative link models
• Phase I monitoring.

MATHEMATICS SUBJECT CLASSIFICATION:

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Acknowledgement

The authors are grateful to the anonymous referees for precious comments which led to improvement in the paper.