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

objectivesGallbladder 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 <10 mm, with cholecystectomy advised if the polyp size increases. USS (including potential cholecystectomies) is resource intense. We evaluated the costs and potential cost-effectiveness of USS in a theoretical UK patient cohort with GBPs.

methodsA health economic model mapped expected management pathways over 2 years for 1000 GBP patients with and without USS, stratified by the initial size of GBP (<6 mm and 6-9 mm). We estimated USS resource and costs under alternate referral thresholds for cholecystectomy. Clinical data were extracted from a large-scale cohort study. TAUS and cholecystectomy 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.

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

conclusionsUsing published data, we demonstrated that, in patients with GBPs <10 mm, 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. ADVANCES IN KNOWLEDGE: • We developed a health economic model, based on published data, to evaluate the cost-effectiveness of guideline-recommended ultrasound surveillance (USS) in patients with gallbladder polyps measuring less than 10 mm in the UK.• The analysis provides a transparent platform to explore potential numbers of trans-abdominal ultrasound studies and cholecystectomies that might be expected if USS protocols are adhered to and discovers important gaps in current evidence that could be filled by additional targeted research.