Filtering strategies in mass population screening for colorectal cancer: an economic evaluation

What is the impact of disease prevalence upon health technology assessment?

As national budgets for health care will remain under stress for the foreseeable future, health technology assessment (HTA) aimed at offering guidance to policy-making will have an increasing role to play in optimizing resources. The emergence of new treatment paradigms and health technologies, and the prevalence studies which determine when a disease is a current or future burden for patients and the community are in the roots of the HTA process. Analysing studies on screening test strategies and health care policy, this paper revisits two key concepts in epidemiology, prevalence and incidence, in order to show their major impact upon HTA. Utilization of the predictive values of screening tests that include prevalence in their calculations, and analysing all options for screening strategies are necessary in HTA. Cost-effectiveness analyses and statistical models should include potential externalities, especially the impact of prevention and treatment on infectious disease prevalence. Beyond estimates of cost-effectiveness ratios, decision makers also need to know by how much their annual health care budget is likely to increase or decrease in the years following the emergence of new technologies: hence the importance of incidence- or prevalence-based economic evaluations. As new paradigms are occurring, especially in the field of oncology, with treatments targeted to 'small' groups of patients identified through genetic testing, prevalence data are strongly needed. Precise estimates of disease prevalence, in general populations as well as in risk or targeted groups, will therefore be necessary to improve HTA process.

Systematic review of economic evidence for the detection, diagnosis, treatment, and follow-up of colorectal cancer in the United Kingdom

Objectives: The aim of this study was to examine the availability and consistency of economic evidence for the detection, diagnosis, treatment, and follow-up of colorectal cancer.

Methods: A systematic review of UK economic evaluations of colorectal cancer interventions was undertaken. Searches were undertaken across ten electronic databases. Studies were critically appraised through reference to a conceptual model of UK colorectal cancer services.

Results: Forty-seven studies met the inclusion criteria. There is a substantial economic evidence base surrounding population-level colorectal screening, surgical procedures, and cytotoxic therapies for the adjuvant and palliative treatment of colorectal cancer. There is limited evidence concerning the diagnosis of suspected colorectal cancer, curative treatments for metastatic disease and follow-up regimens for nonmetastatic disease. No studies were identified relating to the economics of radiotherapy, surveillance of increased-risk groups, end-of-life care, or the management of hereditary colorectal cancer. Where evidence is available, studies are subject to important differences concerning treatment options, decision criteria, and incongruent assumptions concerning the disease and its management.

Conclusions: Across many aspects of the colorectal cancer service, current practice appears to have emerged without the consideration or support of economic evidence. There is a need to develop a common understanding how colorectal cancer models should be structured and implemented.

Colorectal Cancer Screening and Treatment: Review of Outcomes Research

BACKGROUND

Colorectal cancer is the second leading cause of cancer deaths in the United States each year. Screening is effective in reducing colorectal cancer mortality; however, compliance with screening is poor, and factors associated with its compliance are poorly understood. The outcomes of treatment of colorectal cancer (surgery, radiation therapy, and chemotherapy) may have profound effects on quality of life (QOL). Furthermore, colorectal cancer screening and treatment may be expensive, and the costs are important from a policy perspective. This review examines patient-centered outcomes research related to colorectal cancer screening and treatment and outlines the work that has been done in several areas, including patient preferences, QOL, and economic analysis.

METHODS

The literature on the health outcomes associated with colorectal cancer screening and treatment was reviewed. A MEDLINE search of English language articles published from January 1, 1990 through February 2001, was conducted and was supplemented by a review of references of obtained articles. Criteria for study inclusion were identified a priori. A standardized data abstraction form was developed. Summary statistical analyses were performed on the results.

RESULTS

Six hundred eighty-six articles were selected for review. In total, 530 articles were excluded because they either did not include patient-centered outcomes, were duplicate articles, or could not be obtained. There were 156 articles included in the analysis; 67 addressed screening, 18 examined surveillance of high-risk groups, 22 concerned treatment of local disease, 10 examined treatment of local and metastatic disease, and 19 considered treatment of metastatic disease only. One study examined end-of-life care. In 19 studies, the phase of care was unspecified.

CONCLUSIONS

Standardized, disease-specific QOL instruments should be applied in clinical trials so that the results may be compared across different types of interventions. Valid and reliable methods that accurately capture patient preferences regarding screening and treatment should be developed.

The limited incorporation of economic analyses in clinical practice guidelines

BACKGROUND

Because there is increasing concern that economic data are not used in the clinical guideline development process, our objective was to evaluate the extent to which economic analyses are incorporated in guideline development.

METHODS

We searched medline and HealthSTAR databases to identify English-language clinical practice guidelines (1996-1999) and economic analyses (1990-1998). Additional guidelines were obtained from The National Guidelines Clearinghouse Internet site available at http://www.guideline.gov. Eligible guidelines met the Institute of Medicine definition and addressed a topic included in an economic analysis. Eligible economic analyses assessed interventions addressed in a guideline and predated the guideline by 1 or more years. Economic analyses were defined as incorporated in guideline development if 1) the economic analysis or the results were mentioned in the text or 2) listed as a reference. The quality of economic analyses was assessed using a structured scoring system.

RESULTS

Using guidelines as the unit of analysis, 9 of 35 (26%) incorporated at least 1 economic analysis of above-average quality in the text and 11 of 35 (31%) incorporated at least 1 in the references. Using economic analyses as the unit of analysis, 63 economic analyses of above-average quality had opportunities for incorporation in 198 instances across the 35 guidelines. Economic analyses were incorporated in the text in 13 of 198 instances (7%) and in the references in 18 of 198 instances (9%).

CONCLUSIONS

Rigorous economic analyses may be infrequently incorporated in the development of clinical practice guidelines. A systematic approach to guideline development should be used to ensure the consideration of economic analyses so that recommendations from guidelines may impact both the quality of care and the efficient allocation of resources.

[Cost-benefit analysis of screening strategies by human immunodeficiency virus in French blood donors]

BACKGROUND

The residual risk of human immunodeficiency virus (HIV) infection from screened blood transfusion was estimated to be 1.7/10(6) between 1993 and 1995 in France. To orient blood safety policies, we have evaluated what would be, from the perspective of blood banks, the best screening strategy in terms of gain in effectiveness and added costs.

METHODS

A cost-effectiveness analysis compared 20 HIV-testing protocols using (1) available data for performances of the current screening tests; and, (2) national insurance estimates for the cost of tests. Results were expressed as the number of false negative donations that would be avoided and the cost by avoided false negative donation.

RESULTS

For 3 million donated blood units a year and a prevalence of 24 per million, there would be 72 infectious donated blood units, 70.56 of which would be detected by the current screening strategy. The number of additional donated blood infections avoided in all other strategies would be low (between 0.25 and 1.28) with a very high cost (280 million French francs per added false negative avoided or more).

CONCLUSION

A change in screening strategies for blood donations in France is not currently justified. If such a change was to be done, adding p24 antigen detection to the current screening strategy would be one of the worst solutions.

Sensitivity analysis in economic evaluation: a review of published studies

A structured methodological review of journal articles published in 1992 was undertaken to determine whether recently published economic evaluation studies deal systematically and comprehensively with uncertainty. Ninety three journal articles were identified from a range of searches including a computerised search of the MEDLINE CD-Rom database. Articles were reviewed to determine how they had handled uncertainty in: a) data sources; b) generalisability; c) extrapolation; and d) analytic method. Articles were subsequently assessed to determine how they had represented this uncertainty in terms of the overall results of their analysis. Finally, studies were rated on the basis of their overall performance with respect to dealing systematically and comprehensively with uncertainty. Despite the numerous books and articles devoted to the appropriate methods to be employed by analysts conducting economic evaluation, 22 (24%) studies failed to consider uncertainty at all and 35 (38%) studies employed sensitivity analysis in a manner judged as inadequate. In all, 36 (39%) studies were judged to have given at least an adequate account of uncertainty with 13 (14%) of those judged to have provided a good account of uncertainty. Such disappointing results may reflect a general lack of detail in much of the methods literature concerning how sensitivity analysis should be applied and how results should be presented. Journal editors and readers of economic evaluation articles should acquaint themselves with the methods for handling uncertainty in order that they can critically evaluate the extent to which authors have allowed for uncertainties inherent in their analysis.

Is an immunological faecal occult blood test better than Haemoccult? A cost-benefit study

Immunological faecal occult blood (FOB) tests have theoretical advantages over their guaiac counterparts in that they are specific for human haemoglobin. HemeSelect is a semi-quantitative immunological FOB text. Faecal material is eluted into test diluent and serial dilutions are performed. The manufacturers recommend that erythrocyte agglutination at 1:8 dilution is considered a positive reaction. However, further serial dilutions can be carried out and the highest dilution at which the test remains positive determined. At 1:8 dilution, the test has been shown to be more sensitive for symptomatic colorectal cancer than Haemoccult. The aim of this study is to compare the positive rates, neoplastic yield and costs of Haemoccult with HemeSelect at various dilutions in asymptomatic average risk subjects aged 50-74. 1489 subjects satisfactorily completed both tests, 145 (9.7%) returned positive Hemeselect tests (read at 1:8 dilution, 38 patients with neoplasms > or = 1 cm) and 17 positive Haemoccult tests (1.1%). All positive Hemeselect tests were further serially diluted. As the Hemeselect dilution increased to 1:16, 1:32, 1:64 and 1:128 so the positive rate and yields of neoplasms > or = 1 cm progressively fell to 6.8% & 35, 3.6% & 20, 2.7% & 18 and 1.5% & 12, compared with 1.1% and eight neoplasms > or = 1 cm for Haemoccult. In spite of the unit cost of the Hemeselect test being greater than Haemoccult, the cost per neoplasm > or = 1 cm was lower for Hemeselect at 1:8 and 1:16 dilutions than Haemoccult. However, for an equivalent neoplastic yield, Haemoccult was cheaper. Hemeselect is a versatile test whose positive rate can be tailored according to the risk of the group being screened.

Cost-effectiveness analysis, extended dominance, and ethics: a quantitative assessment

The principle of extended dominance is applied in incremental cost-effectiveness analysis to eliminate from consideration strategies whose costs and benefits are improved by a mixed strategy of two other alternatives. Ethical considerations arise, however, in that equal care is not provided to all of the population. To explore these concerns, the authors establish a theoretical health care example with three diagnostic strategies. They demonstrate, both algebraically and geometrically, how to calculate the set of all possible mixed strategies that dominate the strategy eliminated by extended dominance. With the consideration of budget constraints, they define the "coefficient of inequity" as the minimum proportion of the population that would receive an inferior health care strategy if a mixed strategy were to be used instead of the dominated strategy. The implications of cost-effectiveness analysis are made explicit, revealing classic economic concerns about the tradeoff of equity and efficiency.

Population screening for colorectal cancer: comparison between guaiac and immunological faecal occult blood tests

There is concern about the low sensitivity of the guaiac-based Haemoccult test in mass population faecal occult blood (FOB) screening for the early detection of colorectal carcinoma. Hemeselect, an immunological FOB test, has been shown to be more sensitive for symptomatic colorectal cancer and may prove to be a more reliable screening method. In Brighton and Guildford, 4018 asymptomatic subjects aged 50-75 years were offered screening with Haemoccult and Hemeselect. A total of 1489 (37.7 per cent) completed both tests, of which 17 (1.1 per cent) were positive for Haemoccult and 145 (9.7 per cent) positive for Hemeselect (a total of 148 subjects had positive tests). Seven subjects (4.7 per cent) refused to be investigated. Colonic investigation in the remainder revealed nine cancers and 49 patients with 67 adenomas (32 tumours 1 cm or more in size). All cancers (Dukes A, six; B, one; C, two) were detected by Hemeselect (positive predictive value 6.2 per cent) but only one patient was Haemoccult positive (positive predictive value 5.9 per cent). Hemeselect detected 65 adenomas (31 of 1 cm or more) in 48 patients (positive predictive value 33.1 per cent) compared with 11 adenomas (seven of 1 cm or more) in eight patients who were positive for Haemoccult (positive predictive value 47.1 per cent). The test specificity for neoplasia was respectively 94.9 and 99.6 per cent. The Hemeselect positive rate is high but its substantial positive predictive value for cancer warrants continuing evaluation.

Effect of subject age on costs of screening for colorectal cancer

STUDY OBJECTIVE

The aim was to estimate costs and yields of faecal occult blood screening and rescreening for colorectal cancer, for differing age cohorts.

DESIGN

Cost and clinical data were used as the basis for modelling the expected costs, and cost savings, resulting from the treatment of screen detected cancers, as compared with cancers detected by symptomatic presentation.

SETTING

Data were derived from the MRC screening trial currently in progress in Nottingham.

PARTICIPANTS

Approximately 140,000 subjects, age 50-79 years, were randomly allocated to a test (screened) and a control (unscreened) group.

MAIN RESULTS

The net costs of detecting and treating a cancer following colorectal screening fall as the age of the target population increases, owing principally to the increasing incidence of the disease with age. Generally, the marginal detection and treatment costs falls for all age groups with the first screening round, but rises considerably with the second. If allowance is made for cancers prevented as a result of early detection and excision of adenomas, the costs of screening are substantially reduced for all age groups.

CONCLUSIONS

Assuming a cost per QALY (quality adjusted life year gained) equivalent to that derived for the breast cancer screening programme, and a QALY gain from colorectal screening of one year, three screens, each separated by two years, appear economically justified for populations aged 60 years and above. Expected gains from cancer prevention make two screens justifiable for those between 45 and 59 years of age.