Colorectal cancer surveillance in patients with inflammatory bowel disease and primary sclerosing cholangitis: an economic evaluation

BACKGROUND: The cost-effectiveness of annual colonoscopy for detection of colorectal neoplasia among patients with inflammatory bowel disease (IBD) and primary sclerosing cholangitis (PSC) is uncertain. The aim of this study was to determine whether annual colonoscopy among patients with IBD-PSC is cost-effective compared with less frequent intervals from the perspective of a publicly funded health care system.

METHODS: A cost-utility analysis using a Markov model was used to simulate a 35-year-old patient with a 10-year history of well-controlled IBD and a recent diagnosis of concomitant PSC. The following strategies were compared: no surveillance, colonoscopy every 5 years, biennial colonoscopy, and annual colonoscopy. Outcome measures included: costs, number of cases of dysplasia found, number of cancers found and missed, deaths, quality-adjusted life-years (QALYs) gained, and the incremental cost per QALY gained.

RESULTS: In the base-case analysis, no surveillance was the least expensive and least effective strategy. Compared with no surveillance, the cost per QALY of surveillance every 5 years was CAD $15,021. The cost per QALY of biennial surveillance compared with surveillance every 5 years was CAD $37,522. Annual surveillance was more effective than biennial surveillance, but at an incremental cost of CAD $174,650 per QALY gained compared with biennial surveillance.

CONCLUSIONS: More frequent colonoscopy screening intervals improve effectiveness (i.e., detects more cancers and prevents additional deaths), but at higher cost. Health systems must consider the opportunity costs associated with different surveillance colonoscopy intervals when deciding which strategy to implement among patients with IBD-PSC.