A new phase II risk-adjusted CUSUM chart for monitoring surgical performance

In recent years, the use of risk-adjusted control charts for monitoring surgical performance has gained significant attention among researchers. However, many existing monitoring methods only consider patient risk factors that impact surgical performance, and fail to account for other risk factors, such as the surgeon's level of experience. This study presents a new phase II risk-adjusted cumulative sum (CUSUM) chart based on the score test statistic, which includes a risk-adjusted mortality model with dummy variables. This new control chart not only monitors shifts in location and scale parameters related to surgical performance, but also accounts for changes in the risk distribution of the patient population by using dynamic probability control limits (DPCLs). The proposed method is further elaborated and validated through simulations in a practical context, and simulation results indicate that this method is more sensitive to small abnormal changes.