Decision Analysis Model Evaluating the Cost of a Temporary Hydrogel Rectal Spacer before Prostate Radiation Therapy to Reduce the Incidence of Rectal Complications.

PURPOSE - We conducted a decision analysis to evaluate the cost effectiveness of a newly Food and Drug Administration approved rectal spacer gel (SpaceOAR, Augmenix) for the reduction of rectal toxicity of prostate radiation therapy (RT).

METHODS - A decision tree model (TreeAge Pro) was used to compare the strategy of pretherapy placement of a spacing hydrogel before RT to RT alone. The model compared costs associated with rectal complications because of rectal toxicity over a 10-year period across 3 different RT modalities. Rectal toxicity rates were estimated from studies on conformal RT dose escalation, high-dose stereotactic body radiotherapy (SBRT) and low-dose SBRT. Rectal toxicity reduction rates (baseline reduction 70%) were estimated from recently published 15 month data using a rectal spacer. Direct and indirect cost estimates for established grades of rectal toxicity were based on national and institutional costs. Reduction in short-term complications were assumed to carry forward to a reduction in long-term toxicity. One-way and two-way sensitivity analyses were performed.

RESULTS - The overall standard management cost for conformal RT was $3,428 vs. $3,946 with rectal spacer for an incremental cost of $518 over 10 years. A 1-way sensitivity analyses showed the breakeven cost of spacer at $2,332 or a breakeven overall risk reduction of 86% at a cost of $2,850. For high-dose SBRT, spacer was immediately cost effective with a savings of $2,640 and breakeven risk reduction at 36%. However, 2-way spacer cost to risk reduction sensitivity analyses were performed.

CONCLUSIONS -  The use of a rectal spacer for conformal RT results in a marginal cost increase with a significant reduction in rectal toxicity assuming recently published 15 month rectal toxicity reduction is maintained over 10 years. For high-dose SBRT it was cost effective. Further studies would be necessary to validate the long-term benefits of rectal spacers.

Urologic oncology. 2016 Mar 30 [Epub ahead of print]

Ryan Hutchinson, Varun Sundaram, Michael Folkert, Yair Lotan

Departments of Urology, The University of Texas Southwestern Medical Center, Dallas, TX., Departments of Urology, The University of Texas Southwestern Medical Center, Dallas, TX., Departments of Radiation Oncology, The University of Texas Southwestern Medical Center, Dallas, TX., Departments of Urology, The University of Texas Southwestern Medical Center, Dallas, TX.