Determining the True Costs of Treating Small Renal Masses Using Time Driven, Activity Based Costing

We report the implementation of time driven, activity based costing for competing treatments of small renal masses at an academic referral center.

To use time driven, activity based costing we developed a process map outlining the steps to treat small renal masses. We then derived the costs of supplying every resource per unit time. Known as the capacity cost rate, this included equipment and its depreciation (eg price per minute of the operating room table), personnel and space (eg cost per minute to rent clinic space). We multiplied each capacity cost rate by the time for each step. Time driven, activity based costing was defined as the sum of the products for each intervention.

Robot-assisted laparoscopic partial nephrectomy was the most expensive treatment for small renal masses. It was 69.7% more costly than the most inexpensive inpatient modality, laparoscopic radical nephrectomy ($17,841.79 vs $10,514.05). Equipment costs were greater for laparoscopic radical nephrectomy than for open partial nephrectomy. However for laparoscopic radical nephrectomy vs open partial nephrectomy the lower personnel capacity cost rate due to faster operating room time (195.2 vs 217.3 minutes, p = 0.001) and shorter length of stay (2.4 vs 3.7 days, p = 0.13) were the primary drivers in lowering costs. Radiofrequency ablation was 48.4% less expensive than laparoscopic radical nephrectomy ($5,093.83 vs $10,514.05) largely by avoiding inpatient costs. Renal biopsy contributed 3.5% vs 12.2% to the overall cost of robot-assisted laparoscopic partial nephrectomy vs radiofrequency ablation but it may allow for increased active surveillance.

Using time driven, activity based costing we determined the relative resource utilization of competing small renal mass treatments, finding significant cost differences among various treatments. This informs value considerations, which are particularly relevant in the current health care milieu.