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ECONOMIC EVALUATION OF COMPUTED TOMOGRAPHIC COLONOGRAPHY FOR COLORECTAL CANCER SCREENING
S Heitman2, F Au1, R Hilsden1, B Manns2
1Forzani and MacPhail Colon Cancer Screening Centre; 2Department of Medicine, University of Calgary, Calgary, Alberta
Aims: In Canada, colorectal cancer (CRC) screening is recommended for average-risk individuals age 50 - 75. Computed tomography colonography (CTC), or “virtual colonoscopy,” has been proposed as a less invasive alternative to colonoscopy for CRC screening allowing for the detection of both polyps and cancers. However, there is uncertainty regarding the clinical utility and cost-effectiveness of CTC in comparison to other available CRC screening modalities. The objective of this study is to perform an economic analysis of the available CRC screening strategies including CTC using a Canadian perspective.
Methods: Using decision analysis, to compare CRC screening by CTC and the most widely utilized CRC screening strategies (FOBT and colonoscopy) with no screening in average risk Canadians aged 50 to 74. Outcomes included the number of colonoscopies required, cancers, death from cancer, cost and cost per quality-adjusted life year (QALY) gained. Model inputs were obtained from the literature and a meta-analysis of adenoma prevalence. A lifetime horizon was used in the analysis and a discounted rate of 5% was applied to both costs and effects. All costs reported in Canadian dollars and were inflated to 2007.
Results: In a hypothetical 100,000 patient cohort, number of CRC and CRC deaths are shown in the table. CTC was associated with worse clinical outcomes and higher costs than colonoscopy, and thus was “dominated” by colonoscopy. Compared with no screening, FOBT was associated with a cost per QALY gained of $14,290. Compared to FOBT, colonoscopy was associated with a cost per QALY gained of $1,810. However, if the objective of a decision maker is to purchase QALYs at the lowest possible rate, FOBT is eliminated by extended dominance since one can obtain QALYs with colonoscopy (compared with “no screening”) at nearly half the rate for FOBT ($7,937/QALY) by paying an extra $40 per patient.
Conclusions: CRC screening appears cost-effective by conventional standards in comparison to the most common management of average risk Canadians (no screening). Although some uncertainty exists as to the optimal screening strategy, colonoscopy appears to be the optimal strategy under the base-case assumptions if the primary goal is minimize the cost at which QALYs are purchased.
Resources use and cost utility analysis with CRC screening strategies