Loss of efficacy and cost-effectiveness when screening colonoscopy is performed by nongastroenterologists

Background: Specialty of the endoscopist has been related to the postcolonoscopy interval risk of colorectal cancer (CRC). However, the impact of such a difference on the long-term CRC prevention rate by screening colonoscopy is largely unknown.

Methods: A Markov model was constructed to simulate the efficacy and cost of colonoscopy screening according to the specialty of the endoscopist in 100,000 individuals aged 50 years until death. The postcolonoscopy interval CRC risk (0.02%) and the relative risk (1.4) of interval CRC between gastroenterologist (GI) endoscopists and non-GI endoscopists were extracted from the literature. Both efficacy and costs were projected over a steady-state US population. Eventual increase in endoscopic capacity when assuming all procedures to be performed by GI endoscopists was simulated.

Results: According to the simulation model, screening colonoscopy performed by non-GI endoscopists resulted in a 11% relative reduction in the long-term CRC incidence prevention rate compared with the same procedure performed by GI endoscopists. When projected on the US population, the reduced non-GI efficacy resulted in an additional 3043 CRC cases and the loss of $200 million per year. When increasing the relative risk from 1.4 to 2.0, the difference in the prevention rate between GI endoscopists and non-GI endoscopists increased to 19%. It increased further to 38% when also assuming a 3-fold increase in the risk of interval CRC. An additional 165 screening colonoscopies per endoscopist per year would be required to shift all non-GI procedures to GI endoscopists.

Conclusions: When screening colonoscopy is performed by non-GI endoscopists, a substantial reduction in the long-term CRC prevention rate may be expected. Such difference appeared to be greater when a suboptimal efficacy of colonoscopy in preventing CRC was assumed. A 10-year saving of $2 billion may be expected when shifting all screening colonoscopies from non-GI endoscopists to GI endoscopists.