Creating DES screening model with fixed screening intervals
I am trying to develop a DES model for a type of cancer screening for patients with pre-cancerous lesions, of which there are 3 precancerous stages until the development of cancer. With the DES model, I understand that I can model likely progression over time to one of the higher stages or even cancer. Given that the screening occurs at fixed variables, such as 3 years, how do I create a model in which it will let me know which of the precancerous stages it is at that 3 year interval. I do not want the model to determine a change to a higher stage at 1.5 years and then go back to the DES node, because this change will not be recognized until year 3.