A Fast Online Monitoring Approach for Surgical Risks

Risk monitoring has been widely used in health care, further, control charts are often used as monitoring methods for surgical outcomes. Most of the methods can only detect step shifts of position parameters, but cannot take measures on scale parameters. In this paper, we proposed four methods based on EWMA control charts, namely SESOP, STSSO, SESOP-MFIR and STSSO-MFIR, to improve the existing monitoring methods. Specifically, SESOP standardizes variable on the basis of an EWMA charting method; STSSO replaces the statistics of the original EWMA charting method with the score test statistics; for SESOP-MFIR and STSSO-MFIR, we upgrade their control limits from asymptotic to time-varying based on SESOP and STSSO, which enhance the timeliness of the earlier shifts monitoring. In order to verify the improvement of surgical outcomes monitoring, we respectively carry out simulation experiment and a practical application on ESOP and our four methods. SESOP can raise the overall efficiency of detecting shifts; STSSO led to a significant increase in the monitoring stability, especially for small volatilities; the optimization brought by SESOP-MFIR and STSSO-MFIR are more obvious, that the speed of detecting earlier shifts can even be reduced to half of the existing methods. Then, we apply these methods to the SOMIP program of Hong Kong, SESOP-MFIR and STSSO-MFIR have the best performance and can detect early shifts in time. According to the results, the methods we proposed can monitor both early shifts and scale parameters and improve the performance of surgical outcome monitoring in different degrees compared to those existing methods.