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Tuesday, October 23, 2007
P3-46

LIQUID-BASED CYTOLOGY FOR CERVICAL CANCER SCREENING IN CANADA: A COST-EFFECTIVENESS AND COST UTILITY ANALYSIS

Ba Pham, MSc1, Murray Krahn, MD, MSc2, Meg McLachlin, MD3, Barry Rosen, MD4, Beate Sander, RN, MBA, MEcDev2, Paul Grootendorst, PhD5, George Tomlinson, PhD2, Ava John-Baptiste, MHSc6, Maraki Frikemerid, MSc2, Maggie Hong Chen, MMath2, Gloria Woo, MSc5, Andrea Anonychuk, MSc4, Steven M. Carcone, MSc4, Holly Witterman, MSc2, Wendong Chen, MD2, Karen Liu, BA2, Margaret Sampson, PhD, (Candidate)7, and Andrea C. Tricco, MSc8. (1) THETA - Toronto Health Economics & Technology Assessment Centre, Toronto, ON, Canada, (2) University of Toronto, Toronto, ON, Canada, (3) Pathology, University of Western Ontario, London, ON, Canada, (4) University Health Network, Toronto, ON, Canada, (5) Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada, (6) Department of Health Policy, Management and Evaluation, Toronto, ON ON, Canada Canada, (7) Chalmers Research Group, University of Ottawa, Ottawa, ON, Canada, (8) Institute of Population Health, U. of Ottawa, Ottawa, ON, Canada

Purpose: Liquid-based cytology (LBC) was reported to be cost effective compared to conventional cytology (CC), has been widely adopted in some countries but is no longer reimbursed in other public health systems. A cost-effectiveness analysis was commissioned by a national HTA agency to examine the efficiency of LBC and HPV testing for opportunistic screening programs (i.e., 40% coverage) in Canada.

Methods: A 48-state Markov model of cervical cancer disease history was developed to estimate expected direct medical costs (circa 2006), life expectancy and quality-adjusted life years (5% dual discount) associated with nine screening strategies: CC, LBC and LBC+HPV triage of Pap abnormalities every 1, 2, and 3 years among a hypothetical longitudinal cohort of Canadian women. Cost and utility data were derived from targeted literature searches. Accuracy differences between LBC and CC were estimated from a Bayesian hierarchical meta-analysis (n=20 studies). The model was calibrated to data from HPV prevalence studies (n=7), clearance of oncogenic HPV infection (n=2), observed Pap abnormalities (n=1 registry), cancer stage distribution, incidence and related mortality. Parameter uncertainty was evaluated using both univariate and probabilistic sensitivity analyses.

Results: Projected cervical cancer [related death] incidence/100,000 was 8.65 [2.88] for LBC+HPV triage, 9.08 [3.02] LBC, and 9.77 [3.27] CC at 1-year interval. Extending to >= 2-year intervals without increased coverage led to higher incidence. At 1-year interval, discounted life expectancy {lifetime cost} was 19.5579 years {$1,169} for LBC+HPV triage, 19.5577 {$1,187} LBC, and 19.5572 {$1,147} CC.

Compared to 1-year CC, maximal health benefit was achieved with LBC+HPV triage at an incremental cost of $31,639 per LY saved [$12,111 per QALY]. Compared to CC, LBC yielded an incremental cost of $84,342 per LY saved [$29,470 per QALY] at 1-year interval and was dominant at >= 2-year. LBC+HPV triage always dominated LBC. Results were sensitive to screening coverage, follow-up compliance, LBC marginal cost and sensitivity.

A 1-year LBC + HPV triage {CC} program was most likely to produce the highest net health benefits for willingness-to-pay above {below} $10,000 per LY (i.e., PSA).

Conclusion: The economic evidence supports LBC+HPV triage screening. LBC is attractive for >= 2-year screening intervals although how to increase coverage is unknown. Changes to current programs are necessary, especially with reliable assays for detecting high-risk HPV, and the availability of HPV-16/18 vaccines.


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See more of The 29th Annual Meeting of the Society for Medical Decision Making (October 20-24, 2007)