MONITORING MORTALITY RATE OF THE CARDIAC SURGERY USING RISK-ADJUSTED DOUBLE EXPONENTIALLY WEIGHTED MOVING AVERAGE SCHEME

Literature indicates that the statistical process control approach is capable of improving the quality of surgical processes. The use of this approach in the case of real surgical processes is an attractive contribution for researchers. Since risk factors of each patient before a surgery are different potentially, the use of a control chart approaching risk-adjusted is addressed by researchers.The sensitivity of a model to small shift types of the mortality odds ratio is very important for monitoring the quality of a surgery process. Although different schemes have been proposed by researchers to monitor the performance of a medical team, based on the authors' knowledge this research for the first time proposes a risk-adjusted double exponentially weighted moving average (RADEWMA) approach to monitor the mortality rate. The numerical performance analysis of this paper based on average run length (ARL) term for the cardiac surgery addresses that the sensitivity of the proposed risk-adjusted scheme is superior compared to other risk-adjusted chart of literature.In this research the performance of the proposed model is compared comprehensively with risk adjusted P chart (RAP), risk adjusted exponentially weighted moving average (RAEWMA), and risk adjusted cumulative sum (RACUSUM). In this paper for analyzing the performance comparatively, the simulated data is produced based on UK Center for Cardiac Surgery data in the period of 1992-1994. This data is referred to 2218 patients with heart surgery. In this simulation to estimate the parameters of the logistic regression, Parsonnet number is used as an explanatory variable. The comparative performance analysis is reported for different shift cases. The comparative report is analyzed statistically for different values of parameters. For statistical analyzing SPSS software is also used. The new proposed scheme to monitor the mortality odds ratio, can be used in different surgeries of a hospital effectively.