An improved risk-adjusted EWMA charting procedure for multiple surgical outcome monitoring

Monitoring surgical outcomes helps to quickly detect changes in performance. Previous studies have focused on binary outcomes, such as patient survival or death at 30 days postoperatively. However, in many applications, waiting 30 days postoperatively can lead to signaling delays. If surgical performance deteriorates, delayed monitoring due to awaiting the latest surgical outcomes may result in increased adverse events. Therefore, timely updating of patient postoperative outcomes can improve the sensitivity of monitoring procedures. In this paper, we consider real-time updates of patients’ postoperative outcomes and incorporate them into an improved risk-adjusted exponentially weighted moving average (EWMA) chart for multiple surgical outcome monitoring. Simulation results demonstrate that the improved monitoring procedure outperforms the unimproved one in detecting surgical performance deterioration. Finally, a real surgical case study illustrates the application of the improved monitoring procedure.