258 Discrete Event Simulation for Health Technology Assessment
states before and after the event. For example, the diagnosis event could be
represented as the transition between a pre-diagnosis state and a diagnosed
disease state but this is less straightforward than having a diagnosis event.
Moreover, the latter facilitates incorporating a cost of diagnosis, a decision
point, perhaps some implications for other events, and so on.
In some cases, a disease may be readily described by a series of states.These
may represent, for example, stages of a cancer or severity levels. Does that
argue against the use of DES? Usually no because, even in these situations,
there is typically a mixture of events and states, not a pure set of states. DES