title: Cost-effectiveness of aspirin adjuvant therapy in early stage colorectal cancer in older patients.
abstract: OBJECTIVE
  Recent observational studies showed that post-operative aspirin use reduces cancer relapse and death in the earliest stages of colorectal cancer. We sought to evaluate the cost-effectiveness of aspirin as an adjuvant therapy in Stage I and II colorectal cancer patients aged 65 years and older.
  
  
  METHODS
  Two five-state Markov models were constructed separately for Stage I and II colorectal cancer using TreeAge Pro 2014. Two hypothetical cohorts of 10,000 individuals at a starting age of 65 years and with colorectal cancer in remission were put through the models separately. Cost-effectiveness of aspirin was evaluated against no treatment (Stage I and II) and capecitabine (Stage II) over a 20-year period from the United States societal perspective. Extensive one-way sensitivity analyses and multivariable Probabilistic Sensitivity Analyses (PSA) were performed.
  
  
  RESULTS
  In the base case analyses, aspirin was cheaper and more effective compared to other comparators in both stages. Sensitivity analyses showed that no treatment and capecitabine (Stage II only) can be cost-effective alternatives if the utility of taking aspirin is below 0.909, aspirin's annual fatal adverse event probability exceeds 0.57%, aspirin's relative risk of disease progression is 0.997 or more, or when capecitabine's relative risk of disease progression is less than 0.228. Probabilistic Sensitivity Analyses (PSA) further showed that aspirin could be cost-effective 50% to 80% of the time when the willingness-to-pay threshold was varied from USD 20,000 to USD 100,000.
  
  
  CONCLUSIONS
  Even with a modest treatment benefit, aspirin is likely to be cost-effective in Stage I and II colorectal cancer, thus suggesting a potential unique role in secondary prevention in this group of patients.
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore, Singapore.
authors.forename: Swee Sung
authors.initials: SS
authors.lastname: Soon
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, Singapore, Singapore.
authors.forename: Whay-Kuang
authors.initials: WK
authors.lastname: Chia
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore, Singapore.
authors.forename: Mun-ling Sarah
authors.initials: ML
authors.lastname: Chan
authors.affiliation: Department of Radiation Oncology, University of Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: Gwo Fuang
authors.initials: GF
authors.lastname: Ho
authors.affiliation: Department of Medical Oncology, Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Jian
authors.affiliation: Department of Medical Oncology, Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Yan Hong
authors.initials: YH
authors.lastname: Deng
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.
authors.forename: Chuen-Seng
authors.initials: CS
authors.lastname: Tan
authors.affiliation: Department of Oncology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Atul
authors.initials: A
authors.lastname: Sharma
authors.affiliation: National Health and Medical Research Council Clinical Trials Centre, University of Sydney, Sydney, Australia.
authors.forename: Eva
authors.initials: E
authors.lastname: Segelov
authors.affiliation: Department of Digestive Diseases and Nutrition, Tata Memorial Hospital, Mumbai, India.
authors.forename: Shaesta
authors.initials: S
authors.lastname: Mehta
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom.
authors.forename: Raghib
authors.initials: R
authors.lastname: Ali
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, Singapore, Singapore.
authors.forename: Han-Chong
authors.initials: HC
authors.lastname: Toh
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore, Singapore.
authors.forename: Hwee-Lin
authors.initials: HL
authors.lastname: Wee
mesh_terms: D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000191:economics / Q000627:therapeutic use; D000964:Antimetabolites, Antineoplastic / Q000191:economics / Q000627:therapeutic use; D001241:Aspirin / Q000191:economics* / Q000627:therapeutic use*; D000069287:Capecitabine; D017024:Chemotherapy, Adjuvant / Q000379:methods; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D003362:Cost-Benefit Analysis; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000191:economics / Q000627:therapeutic use; D005472:Fluorouracil / Q000031:analogs & derivatives / Q000191:economics / Q000627:therapeutic use; D006801:Humans; D008390:Markov Chains; D018803:Models, Economic; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D017063:Outcome Assessment, Health Care / Q000191:economics / Q000706:statistics & numerical data; D019057:Quality-Adjusted Life Years; D012074:Remission Induction; D015203:Reproducibility of Results; D055502:Secondary Prevention / Q000379:methods
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000964:Antimetabolites, Antineoplastic; D003841:Deoxycytidine; D000069287:Capecitabine; D001241:Aspirin; D005472:Fluorouracil