Cost-effectiveness of trans-abdominal ultrasound for gallbladder cancer surveillance in patients with gallbladder polyps less than 10 mm in the United Kingdom.

Abstract

Objective: Gallbladder polyps (GBPs) are commonly detected with trans-abdominal ultrasound (TAUS). Gallbladder cancer (GBC) is associated with GBPs but the risk of malignancy is low. International guidelines recommend ultrasound surveillance (USS) in selected cases of GBPs <10mm, with cholecystectomy advised if polyp size increases. USS (including potential surgeries) is resource intense. We evaluated the costs and potential cost-effectiveness of USS in a theoretical UK patient cohort with GBPs.

Methods: A health economic model mapped expected management pathways over 2-years for 1,000 GBP patients with and without USS, stratified by initial size of GBP (<6mm and 6-9mm). We estimated USS resource and costs under alternate thresholds for surgery. Clinical data were extracted from a large-scale cohort study. TAUS and surgery costs were based on NHS tariffs. GBC costs were estimated from the literature. Outcomes included USS costs, expected numbers of GBC and incremental cost for each case of GBC avoided.

Results: The 2-year additional cohort costs of USS (n=number of additional surgeries) were estimated between £213,441 (n = 50) and £750,045 (n = 253) in GBPs <6mm, and between £420,275 (n = 165) and £531,297 (n = 207) in GBPs 6-9mm, balanced against avoidance of 1.3 (<6mm) and 8.7 (6-9mm) cases of GBC. Model findings were robust to plausible changes in inputs.

Conclusions: Using published data, we demonstrated that, in patients with GBPs <10mm, the costs of USS to avoid GBC outweigh potential GBC cost offsets, and would result in high rates of cholecystectomy. Additional evidence is needed to establish the formal cost-effectiveness of GBP USS in the UK.