Forecasting Surgical Groups’ Total Hours of Elective Cases for Allocation of Block Time

Abstract

Background Allocation of the correct amount of operating room (OR) " block time " can provide surgeons with access to sufficient OR time to complete their elective cases while opti-mally matching staffing with the elective case workload (to maximize labor productivity). To evaluate how to predict accu-rately total hours of elective cases performed by a surgical group using data from surgical services information systems, the authors addressed the following questions: (1) How many previous 4-week periods of data should be used to minimize error in forecasting a surgical group's total hours of elective cases? (2) Using the number of 4-week periods from question #1, can we detect trends or correlations between successive periods that could be used to improve forecasting accuracy? (3) How can results from questions #1 and #2 be used to calculate an upper prediction bound (upper limit) for the total hours of elective cases that will be completed in a future period? Predic-tion bounds can be used to budget staffing accurately. Methods: Time series analysis was performed on total hours of elective cases over 39 consecutive 4-week periods from 17 surgical groups. Results: The average of 12 consecutive periods' total hours of elective cases had an appropriate error profile. The observa-tions within each series of 12 consecutive 4-week periods fol-lowed a normal distribution, with each observation of total hours of elective cases not correlated with the subsequent ob-servation.