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The impact of CT colonography for colorectal cancer screening on the UK NHS: costs, healthcare resources and health outcomes |
Sweet A, Lee D, Gairy K, Phiri D, Reason T, Lock K |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. CRD summary The aim was to assess the budget impact and health care outcomes of adding computed tomography (CT) colonography to faecal occult blood testing (FOBT) to screen for colorectal cancer, in individuals aged 50 years or older. Adding CT colonography, to triage patients with positive FOBT results, could reduce costs. The uncertainty around the sensitivity and specificity of FOBT and CT colonography was not explored, and the authors' conclusions represent a budget impact analysis rather than a cost-effectiveness analysis. Type of economic evaluation Cost-effectiveness analysis Study objective The aim was to assess the budget impact and health care outcomes of adding computed tomography (CT) colonography to faecal occult blood testing (FOBT) to screen for colorectal cancer, using a dynamic cohort of 100,000 individuals aged 50 years or older. Interventions The three screening options were biennial FOBT; biennial FOBT with CT colonography follow-up for positive results; and five-yearly CT colonography. For biennial FOBT, positive results were followed-up with optical colonoscopy, and polypectomy, if necessary. For the other two options, patients with high-risk polyps detected by CT colonography were followed up with optical colonoscopy, and polypectomy, if necessary. Methods Analytical approach:The economic evaluation was based on a published Markov model (Lee, et al. 2010, see ‘Other Publications of Related Interest’ below for bibliographic details), with a 10-year time horizon. The authors stated that the perspective of the UK NHS was adopted.
Effectiveness data:The clinical data were the sensitivity and specificity of each screening option and were from a selection of relevant published studies. The authors stated that there was no evidence on the sensitivity and specificity of CT colonoscopy for patients with a positive FOBT result, so they multiplied the sensitivities and the complements of the specificities to derive the combined sensitivity and specificity estimates. The authors used data reported in the literature to make a number of assumptions for the clinical inputs, including the adverse events from optical colonoscopy and CT colonography, and the natural history of colorectal cancer.
Monetary benefit and utility valuations:Not relevant.
Measure of benefit:The main measures of benefit were the number of colorectal cancer cases and the number of deaths from colorectal cancer.
Cost data:The economic analysis included the costs of screening and the costs of treating adverse events and cancer. The cost data were from official UK sources including tariffs from Payment by Results, NHS reference costs, and major-procedure codes for surgical interventions. The costs were reported in 2007 UK pounds sterling (£).
Analysis of uncertainty:The uncertainty was assessed in one-way sensitivity analyses, varying the key input parameters, including the patient age range, the rate of uptake of primary screening, the rate of uptake of follow-up and diagnostic tests, the threshold polyp size for referral to optical colonoscopy, and the CT colonography screening frequency. Results Over 10 years for the cohort of 100,000 individuals, the total costs were £15.75 million for biennial FOBT, £14.98 million for biennial FOBT then CT colonography, and £19.10 for five-yearly CT colonography.
Compared with biennial FOBT, biennial FOBT then CT colonography was associated with 2,219 more CT colonography scans, and five-yearly CT colonography with 39,854 more scans. The biennial FOBT then CT colonography resulted in 1,059 fewer therapeutic optical colonoscopies and 615 fewer non-therapeutic optical colonoscopies, and the five-yearly CT colonography resulted in 534 fewer therapeutic optical colonoscopies and 2,811 more non-therapeutic optical colonoscopies.
Compared with biennial FOBT, biennial FOBT then CT colonography was associated with a similar number of screen-detected and diagnosed colorectal cancer cases and more colorectal cancer deaths; and CT colonography was associated with 153 fewer diagnosed colorectal cancer cases and 25 fewer colorectal cancer deaths. Authors' conclusions The authors concluded that adding CT colonography to biennial FOBT, to triage patients with positive FOBT results, could reduce the costs for colorectal cancer screening. CRD commentary Interventions:The selection of the comparators was appropriate, as biennial FOBT was the usual practice in the UK.
Effectiveness/benefits:The clinical data came from selected published studies, the details of which were not reported. A systematic review of literature does not appear to have been conducted, making it unclear if all the best available data were used. It is possible that the sensitivity of FOBT and CT colonography combined was underestimated and the specificity was overestimated if CT colonography performance was better in a FOBT-positive population than in the general population. The sensitivity and specificity estimates were not varied in the sensitivity analyses even though there was no direct evidence for them. Using a disease-specific benefit measure appears to have been appropriate for this analysis.
Costs:The cost categories and data sources were consistent with the perspective. The resource types and how these were valued were reported. Discounting was not conducted, and this was justified as being less relevant for budget impact analyses.
Analysis and results:No synthesis of the health benefits and costs was conducted, as the main focus was to assess the budget impact. In effect, a cost-consequences analysis was conducted. The results of the study were clearly reported. The uncertainty surrounding the sensitivity and specificity of FOBT and CT colonography was not explored. The authors acknowledged some limitations to their study.
Concluding remarks:The uncertainty around the sensitivity and specificity of FOBT and CT colonography was not explored, and the authors' conclusions represent a budget impact analysis rather than a cost-effectiveness analysis. Funding Funding received from GE Healthcare, a manufacturer of CT colonography equipment. Bibliographic details Sweet A, Lee D, Gairy K, Phiri D, Reason T, Lock K. The impact of CT colonography for colorectal cancer screening on the UK NHS: costs, healthcare resources and health outcomes. Applied Health Economics and Health Policy 2011; 9(1): 51-64 Other publications of related interest Lee D, Muston D, Sweet A, et al. Cost effectiveness of CT colonography for UK NHS colorectal cancer screening of asymptomatic adults aged 60-69 years. Applied Health Economics and Health Policy 2010; 8(3): 141-154. Indexing Status Subject indexing assigned by NLM MeSH Age Factors; Aged; Colonography, Computed Tomographic /economics /statistics & Colorectal Neoplasms /diagnosis /economics /prevention & Cost-Benefit Analysis /economics; Great Britain; Humans; Mass Screening /economics /statistics & Middle Aged; Models, Econometric; Occult Blood; Outcome and Process Assessment (Health Care); control /therapy; numerical data; numerical data AccessionNumber 22011000243 Date bibliographic record published 04/05/2011 Date abstract record published 31/08/2011 |
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