title: Can colonoscopy remain cost-effective for colorectal cancer screening? The impact of practice patterns and the Will Rogers phenomenon on costs.
abstract: OBJECTIVE
  The adenoma detection rate (ADR) in screening colonoscopy is higher than original cost-effectiveness models estimated. Future colorectal cancer (CRC) risk is decreased once the ADR is 20%, but it is unclear how much additional protection is provided with higher ADRs. We modeled the impact of a high ADR on future CRC risk and surveillance colonoscopy burden.
  
  
  METHODS
  We created three hypothetical scenarios for 100,000 average-risk individuals undergoing screening colonoscopy at age 50: (i) 20% ADR with 30% future CRC risk reduction; (ii) 50% ADR with 30% future CRC risk reduction; and (iii) 50% ADR with 50% future CRC risk reduction. After colonoscopy, patients could have high-risk or low-risk adenomas, or no adenomas.
  
  
  RESULTS
  When the ADR increases from 20% to 50% but no additional CRC cases are prevented, future CRC risk for each group is still reduced, because lower-risk patients migrate into apparently higher-risk groups (the Will Rogers phenomenon). Future risk is further reduced if a 50% ADR leads to greater protection from CRC. However, despite the reductions in group-specific and overall future CRC risk, 34,635 additional surveillance colonoscopies are performed before the cohort is 60 years old when the ADR is 50% compared with 20%.
  
  
  CONCLUSIONS
  If current surveillance practices continue along with high ADRs, screening colonoscopy may not remain cost-effective.
authors.affiliation: Division of Gastroenterology and Hepatology, University of Colorado Denver, Aurora, Colorado 80045, USA. gregory.austin@ucdenver.edu
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Austin
authors.forename: Blair
authors.initials: B
authors.lastname: Fennimore
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Ahnen
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000191:economics; D003113:Colonoscopy / Q000191:economics*; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000191:economics; D003362:Cost-Benefit Analysis; D055088:Early Detection of Cancer / Q000191:economics*; D005260:Female; D017048:Health Care Costs; D006801:Humans; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians' / Q000191:economics*