The Impact of the Variability of Patient Flow and Service Time on the Efficiency of Large-Scale Outpatient Systems

The outpatient services in large-scale hospitals consist of multiple specialty departments, servers, and multiple stages. Single-server and small clinics have been extensively studied, but little attention has been paid to the modeling and evaluation of large-scale outpatient care systems. In this study, complex patient routings in large-scale outpatient systems are specified, and three patient flow variability factors (e.g., return rate, first-lab-visit rate, and second-lab-visit rate) are discussed. The measures, namely, patient satisfaction, resource utilization, and system efficiency, are based on the ratios of ``effective time'' over ``holistic time.'' The purpose of this study is to find the effect of patient flow variability and service time variability on the efficiency of a multistage outpatient system. A discrete-event simulation (DES) model is built, and a real case is presented. A novel method to generate the transition matrix based on patient flow variability is proposed. Our results show that the patient flow variability has a negative impact on patient satisfaction and a positive effect on resource utilization and system efficiency. Service time variability has a negative impact on resource utilization but has a combined effect on patient satisfaction and system efficiency with patient flow variability. The interactions between the two factors are thoroughly discussed.