Using simulation modelling for evaluating screening services for diabetic retinopathy

In using discrete event simulation for planning services in the health sector, epidemiologists and clinicians were closely involved in model design, data collection, analysis, validation and experimentation. For patients with diabetes, loss of sight can be prevented by timely treatment if detected sufficiently early. Simulation models, using the patient oriented simulation technique, POST, have been developed to assist policy makers in the choice of screening strategy in terms of operator, equipment, frequency of screening and target population. The models describe the progress of a population of diabetic patients, including new arrivals, over 25 years. The initial population were given characteristics retrospectively and the parameters were derived from peer reviewed publications. The results from the models show that the interval between screening is more important than screening sensitivity. The simulation can determine the expected workload and the amount of vision loss prevented for any population group.