Colorectal cancer (CRC) is a feared complication of chronic ulcerative colitis (UC). Annual endoscopic surveillance is recommended to detect early neoplasia. 5-aminosalicylates (5-ASAs) may prevent some UC-associated CRC. Therefore, in patients prescribed 5-ASAs for maintenance of remission, annual surveillance might be overly burdensome and inefficient. We aimed to determine the ideal frequency of surveillance in patients with UC maintained on 5-ASAs.
We performed systematic reviews of the literature, and created a Markov computer model simulating a cohort of 35 year-old men with chronic UC, followed until age 90. Twenty-two strategies were modeled: Natural History (no 5-ASA or surveillance), surveillance without 5-ASA at intervals of 1 to 10 years, 5-ASA plus surveillance every 1 to 10 years, and 5-ASA alone. The primary outcome was the ideal interval of surveillance in the setting of 5-ASA maintenance, assuming a third-party payer was willing to pay $100,000 for each quality-adjusted life-year (QALY) gained.
In the Natural History strategy, the CRC incidence was 30%. Without 5-ASA, annual surveillance was the ideal strategy, preventing 89% of CRC and costing $69,100 per QALY gained compared to surveillance every 2 years. 5-ASA alone prevented 49% of CRC. In the setting of 5-ASA, surveillance every 3 years was ideal, preventing 87% of CRC. 5-ASA with surveillance every 2 years cost an additional 147,500 per QALY gained, and 5-ASA with annual surveillance cost nearly $1 million additional per QALY gained compared to every 2 years. In Monte Carlo simulations, surveillance every 2 years or less often was ideal in 95% of simulations.
If 5-ASA is efficacious chemoprevention for UC-associated CRC, endoscopic surveillance might be safely performed every 2 years or less often. Such practice could decrease burdens to patients and to endoscopic resources with a minimal decrease in quality-adjusted length of life, since 5-ASA with annual surveillance may cost nearly $1 million per additional QALY gained.