Aspirin as an Adjunct to Screening for Prevention of Sporadic Colorectal Cancer: A Cost-Effectiveness Analysis

Aspirin as an Adjunct to Screening for Prevention of Sporadic Colorectal Cancer: A Cost-Effectiveness Analysis

From University of California, San Francisco, San Francisco, California; and University of Michigan, Ann Arbor, Michigan.

Abstract

Background: Aspirin may decrease colorectal cancer incidence, but its role as an adjunct to or substitute for screening has not been evaluated.

Objective: To examine the potential cost-effectiveness of aspirin chemoprophylaxis in relation to screening.

Design: Markov model.

Data Sources: Literature on colorectal cancer epidemiology, screening, costs, and aspirin chemoprevention (1980–1999).

Target Population: General U.S. population.

Time Horizon: 50 to 80 years of age.

Perspective: Third-party payer.

Intervention: Aspirin therapy in patients screened with sigmoidoscopy every 5 years and fecal occult blood testing every year (FS/FOBT) or colonoscopy every 10 years (COLO).

Outcome Measures: Discounted cost per life-year gained.

Results of Base-Case Analysis: When a 30% reduction in colorectal cancer risk was assumed, aspirin increased costs and decreased life-years because of related complications as an adjunct to FS/FOBT and cost $149 161 per life-year gained as an adjunct to COLO. In patients already taking aspirin, screening with FS/FOBT or COLO cost less than $31 000 per life-year gained.

Results of Sensitivity Analysis: Cost-effectiveness estimates depended highly on the magnitude of colorectal cancer risk reduction with aspirin, aspirin-related complication rates, and the screening adherence rate in the population. However, when the model's inputs were varied over wide ranges, aspirin chemoprophylaxis remained generally non–cost-effective for patients who adhere to screening.

Conclusions: In patients undergoing colorectal cancer screening, aspirin use should not be based on potential chemoprevention. Aspirin chemoprophylaxis alone cannot be considered a substitute for colorectal cancer screening. Public policy should focus on improving screening adherence, even in patients who are already taking aspirin.

Article and Author Information

Acknowledgment: The authors thank Dr. David Glidden of the University of California, San Francisco, General Clinical Research Center for assistance with the Monte Carlo simulation.
Grant Support: By grants from the National Institutes of Health to the University of Michigan and the University of California, San Francisco, General Clinical Research Centers (M01-RR00042 and M01-RR00079), including a Clinical Associate Physician Award to Dr. Ladabaum.
Requests for Single Reprints: Uri Ladabaum, MD, MS, Division of Gastroenterology, S-357, Box 0538, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0538.
Current Author Addresses: Dr. Ladabaum: Division of Gastroenterology, S-357 Box 0538, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0538.
Dr. Lee Chopra: Division of Geriatric Medicine, 1500 East Medical Center Drive, CCGCB 1127/0920, University of Michigan, Ann Arbor, MI 48109.
Dr. Huang: Mental Health Research Institute, 205 Zina Pitcher Place, University of Michigan, Ann Arbor, MI 48109-0720.
Dr. Scheiman: Division of Gastroenterology, 3912 Taubman Center, University of Michigan, Ann Arbor, MI 48109-0362.
Dr. Chernew: Department of Health Management and Policy, SPH-2 HMP, 109 Observatory, University of Michigan, Ann Arbor, MI 48109-2029.
Dr. Fendrick: Division of General Medicine, 1500 East Medical Center Drive, University of Michigan, Ann Arbor, MI 48109.
Author Contributions: Conception and design: U. Ladabaum, C. Lee Chopra, G. Huang, J.M. Scheiman, M.E. Chernew, A.M. Fendrick.
Analysis and interpretation of the data: U. Ladabaum, C. Lee Chopra, G. Huang, J.M. Scheiman, M.E. Chernew, A.M. Fendrick.
Drafting of the article: U. Ladabaum, J.M. Scheiman, A.M. Fendrick.
Critical revision of the article for important intellectual content: U. Ladabaum, J.M. Scheiman, A.M. Fendrick.
Final approval of the article: U. Ladabaum, J.M. Scheiman, M.E. Chernew, A.M. Fendrick.
Provision of study materials or patients: U. Ladabaum.
Statistical expertise: U. Ladabaum.
Administrative, technical, or logistic support: U. Ladabaum, J.M. Scheiman, M.E. Chernew, A.M. Fendrick.
Collection and assembly of data: U. Ladabaum, C. Lee Chopra.