A cost-effectiveness analysis of sentinel lymph node detection in vulvar cancer by preoperative lymphoscintigraphy versus intraoperative detection alone

Abstract

Objective: To determine cost-effectiveness of preoperative lymphoscintigraphy (LSG) for detection of inguinofemoral sentinel lymph nodes (SLN).

Method: We compared the use of preoperative LSG prior to SLN excision versus omission of preoperative LSG. The two outcomes were death or survival. Costs associated with the procedure were determined by CPT code and published estimates. Cost analysis was performed using Treeage software, and incremental cost-effectiveness ratios (ICERs) were calculated. The measure of effectiveness was incremental survival benefit. ICER thresholds for considering LSG to be cost-effective were based on the value of a statistical life (VSL).

Results: Using a baseline probability of 0.93 for finding SLN with LSG, our model estimated LSG costs were $2783.84 with 84.7% survival. Our model then estimated the cost and survival without LSG by varying the SLN detection rate. Survival was equivalent when probability of SLN detection without LSG was 0.93. If detection without LSG was >0.93, not performing LSG was the dominant strategy. Costs were equal when probability of finding SLN without LSG was 0.6. For any SLN detection without LSG below 0.6, performing LSG was the dominant strategy. Formal cost-effectiveness analysis was performed using ICERs for probabilities from 0.60 to 0.93. In this range, costs were higher with LSG, but survival was improved. As long as the incremental detection with LSG was at least 1.05% to 1.47% higher, LSG was cost-effective with ICERs below the VSL.

Conclusion: In our model, LSG is cost-effective as long as it increases detection of SLN by at least 1.05-1.47%.