Waiting time information services: an evaluation of how well clearance time statistics can forecast a patient's wait.

Governments in some countries have created web-based information services so that patients requiring elective surgery can compare the waiting times of surgical units. This study investigated how accurately the waiting times of patients about to join a waiting list can be forecast by various clearance time statistics. It used 3 years of elective surgical activity data that covered 46 surgeons in 10 specialties within a public hospital. Six clearance time functions were tested, and the best function was compared with average waiting time statistics derived from census and throughput data. The forecast accuracy of the clearance time functions was found to be greatly affected by the characteristics and behaviour of a surgeon's waiting list. Although there was less difference in performance among the six functions, systematic differences between them were also found. The best of these performed better than the statistics derived from waiting time data, especially where waiting times exceeded 6 months. Yet, its accuracy was still poor. For each surgeon with an average waiting time of more than 6 months, at least 20% of patients waited more than 90 days beyond the clearance time forecast. Consequently, while waiting time information services should consider adopting the clearance time approach, they need to be explicit about its statistical limitations.