Scheduling medical procedures: how one single delay begets multiple subsequent delays

Background: Delay is a common feature of medical disease management. Delays occur because schedules are filled, patients forget their appointment, equipment is unavailable, or because medical and non-medical complications interfere with the planned procedure. The aim of the present analysis is to model how one single delay can lead to multiple subsequent delays. Methods: The consecutive stream of delays is analyzed in terms of a stochastic process comprising of a random sum of random time periods. Any untoward event causes a procedural delay, which provides a time window of opportunity for yet another delaying event to occur. Results: The stochastic model explains why even a single initial delay can easily lead to a multitude of subsequent delays. The expected overall delay is always longer than the initial delay caused by the deferment of the initial procedure. The analysis demonstrates how in individual patients an initially short delay may subsequently expand into days or weeks. Conclusion: Because a single delay can easily burgeon into a lengthy series of multiple delays, the primary goal should be to avoid the precipitating delay at the onset.