Determining Variable Costs in the Acute Urolithiasis Cycle of Care Through Time-driven Activity-based Costing

Objective. To characterize full cycle of care costs for managing an acute ureteral stone using time-driven activity-based costing.
Methods. We defined all phases of care for patients presenting with an acute ureteral stone and built an overarching process map. Maps for sub-processes were constructed through interviews with providers and direct observation of clinical spaces. This facilitated calculation of cost per minute for all aspects of care delivery, which were multiplied by associated process times. These were added to consumable costs to determine cost for each specific step and later aggregated to determine total cost for each sub-process. We compared costs of eight common clinical pathways for acute stone management, defining total cycle of care cost as the sum of all sub-processes that comprised each pathway.
Results. Cost per sub-process included $920 for emergency department (ED) care, $1665 for operative stent placement, $2368 for percutaneous nephrostomy tube placement, $106 for urology clinic consultation, $238 for preoperative center visit, $4057 for ureteroscopy with laser lithotripsy (URS), $2923 for extracorporeal shock wave lithotripsy, $169 for clinic stent removal, $197 for abdominal x-ray, and $166 for ultrasound. The lowest cost pathway ($1388) was for medical expulsive therapy, whereas the most expensive pathway ($8002) entailed a repeat ED visit prompting temporizing stent placement and interval URS.
Conclusion. We found a high degree of cost variation between care pathways common to management of acute ureteral stone episodes. Reliable cost accounting data and an understanding of variability in clinical pathway costs can inform value-based care redesign as payors move away from pure fee-for-service reimbursement.