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Cost-effectiveness of mass screening for colorectal cancer: choice of fecal occult blood test and screening strategy |
Sobhani I, Alzahouri K, Ghout I, Charles DJ, Durand-Zaleski I |
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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 objective was to compare the cost-effectiveness of different mass screening programmes, for people without symptoms who were invited for colorectal cancer screening. The authors concluded that a three-sample immunological faecal occult blood test, with 50 nanograms per mL as a cut-off, was cost-effective and should be evaluated prospectively. If the assumption that the costs of the immunochemical test are equivalent to those of the guaiac test is correct, the authors' conclusions appear to be reasonable. Type of economic evaluation Study objective The objective was to compare the cost-effectiveness of different mass screening programmes, for people without symptoms who were invited for colorectal cancer screening. Interventions The study evaluated a successive two-yearly colorectal cancer screening programme, using two types of faecal occult blood test (FOBT): an immunochemical test and the guaiac test (three samples). Four immunochemical tests were considered: the MagStream, with one sample, and the OC-SENSOR, with one, two, or three samples. The haemoglobin thresholds were 20 nanograms (ng) per mL for the MagStream test, 75 or 100ng per mL for the one- or two-sample OC-SENSOR tests, and 50, 75, 100 or 150ng per mL for the three-sample test. These tests were compared over 12 years (six tests) or 24 years (12 tests). Colonoscopy every 10 years was included in the 12-year analysis. Methods Analytical approach:A state-transition Markov model was developed to model the natural history of colorectal cancer, with the annual risks of moving between states adjusted for age. The time horizon was until death or the age of 100 years. The authors reported that the perspective was that of the payer, which was the health care system. Effectiveness data:Wherever possible, the clinical and effectiveness data were from published French sources. The remaining sources were studies conducted in other countries. The main effectiveness estimates were the sensitivity and specificity of the various FOBTs in detecting colorectal cancer. These estimates were from three published studies. Monetary benefit and utility valuations:The utilities were from published studies, conducted in countries other than France. Measure of benefit:Quality-adjusted life-years (QALYs) were the measure of benefit. Future outcomes were discounted at an annual rate of 3%. Cost data:The direct costs were those of the screening programme, diagnosis, and treatment, which included follow-up costs. The costs of the screening programme were from a French trial. The cost per sample for the immunochemical and guaiac tests were assumed to be the same. The costs of treating colorectal cancer were from a study of the French population, and those of follow-up were from another published French study. All costs were reported in Euros (EUR). The price year was 2010 and future costs were discounted at an annual rate of 3%. Analysis of uncertainty:One-way sensitivity analyses were carried out by varying the participation rate, the compliance with colonoscopy, the cost of the immunochemical tests, and the cost of colonoscopy. Results In the 12-year analysis, the average QALYs gained per patient were 8.944 with guaiac FOBT and 8.956 with immunochemical FOBT (best option). Comparing the different immunochemical tests, the average QALYs gained varied from 8.947 with the MagStream to 8.956 with the OC-SENSOR three samples and a 50ng per mL threshold. The average cost per patient was EUR 584 with guaiac FOBT and EUR 694 with immunochemical FOBT (most effective test). Comparing the different immunochemical tests, the average cost per patient varied from EUR 693 with OC-SENSOR one sample and a 100ng per mL threshold, to EUR 1,003 with OC-SENSOR three samples and a 75ng per mL threshold. Comparing immunochemical FOBT (most effective test; OC-SENSOR three sample, with a 50ng per mL threshold) with guaiac FOBT, the additional cost per QALY gained was EUR 8,821. The OC-SENSOR one sample, with a 75ng per mL threshold, had an incremental cost-utility ratio, over the guaiac test, of EUR 20,700 per QALY gained. All the other immunochemical tests were dominated, as they were more costly and less effective than another option. The incremental cost-effectiveness of colonoscopy screening every 10 years, compared with immunochemical FOBT was EUR 319,000. The results were sensitive to changes in the participation rates, and the cost of colonoscopy, but the immunochemical three-sample test, with a threshold of 50ng per mL, remained the best option. Authors' conclusions The authors concluded that a three-sample immunological test, with 50ng per mL as a positive cut-off, was cost-effective and should be evaluated prospectively in a mass screening programme. CRD commentary Interventions:The interventions were described, but this could have been clearer. The guaiac test was the usual test in France at the time. Effectiveness/benefits:The clinical and effectiveness data were mainly from published studies. These sources and the baseline estimates were reported, but the authors did not report how the published studies were identified. This means it is unclear if all the relevant evidence was analysed. The instrument used to measure the utility weights was not reported, but the source was referenced. Costs:The perspective was explicitly reported and it appears that all the major costs relevant to this health care system perspective were analysed. The sources for these costs were reported and their quality was mixed; some costs were appropriately obtained from local studies. There was no evidence for the purchase and analysis costs for the immunochemical FOBTs, and these were assumed to be the same as those the guaiac test. The costs for the immunochemical tests were increased by 50% in the sensitivity analysis. The price year, currency, time horizon, and discount rate were all reported. Analysis and results:A Markov model was used to synthesise the cost and outcome information. The model structure and details were clearly reported, and a diagram was given. The uncertainty in the model was tested in one-way sensitivity analyses, which go some way towards evaluating uncertainty, but a probabilistic sensitivity analysis could have assessed the overall model uncertainty. As the main limitation to their study, the authors reported that there was a lack of data on the true prevalence of asymptomatic colorectal cancer, and they had to use best estimates. Concluding remarks:If the assumption that the cost of the immunochemical FOBT is equivalent to that of the guaiac FOBT is correct, the authors' conclusions appear to be reasonable. Bibliographic details Sobhani I, Alzahouri K, Ghout I, Charles DJ, Durand-Zaleski I. Cost-effectiveness of mass screening for colorectal cancer: choice of fecal occult blood test and screening strategy. Diseases of the Colon and Rectum 2011; 54(7): 876-886 Indexing Status Subject indexing assigned by NLM MeSH Aged; Colonoscopy /economics; Colorectal Neoplasms /diagnosis /economics /epidemiology; Cost-Benefit Analysis; Female; France /epidemiology; Guaiac /economics; Guidelines as Topic; Humans; Immunologic Tests /economics /methods; Incidence; Indicators and Reagents /economics; Male; Mass Screening /economics /methods; Middle Aged; Models, Economic; Occult Blood; Reproducibility of Results AccessionNumber 22011001433 Date bibliographic record published 12/10/2011 Date abstract record published 05/03/2012 |
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