Aspirin as an adjunct to screening for prevention of sporadic colorectal cancer. A cost-effectiveness analysis.
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.


METHODS
Markov model.


METHODS
Literature on colorectal cancer epidemiology, screening, costs, and aspirin chemoprevention (1980-1999).


METHODS
General U.S. population.


METHODS
50 to 80 years of age.


CONCLUSIONS
Third-party payer.


METHODS
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).


METHODS
Discounted cost per life-year gained.


RESULTS
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
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.
Ladabaum
U
U
Division of Gastroenterology, S-357 Box 0538, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0538, USA.
Chopra
C L
CL
Huang
G
G
Scheiman
J M
JM
Chernew
M E
ME
Fendrick
A M
AM
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000191:economics / Q000627:therapeutic use*; D001241:Aspirin / Q000191:economics / Q000627:therapeutic use*; D003113:Colonoscopy / Q000191:economics; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D006801:Humans; D008390:Markov Chains; D008403:Mass Screening / Q000191:economics*; D009780:Occult Blood; D012680:Sensitivity and Specificity; D012812:Sigmoidoscopy / Q000191:economics
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001241:Aspirin