Assessment of utilization efficiency using machine learning techniques: A study of heterogeneity in preoperative healthcare utilization among super-utilizers

•Among preoperative super-utilizers, 5 distinct patterns of preoperative utilization were identified.•Variations in utilization patterns were associated with postoperative outcomes and subsequent health care costs.•The group with the lowest preoperative expenditure had the highest complication (16.5%) and 90-day readmission rate (24.3%).•Annual expenditure dropped as much as 84% postoperatively, indicating a differential effect of surgery on health care costs.