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Cost analysis in a population based screening programme for colorectal cancer: comparison of immunochemical and guaiac faecal occult blood testing |
Castiglione G, Zappa M, Grazzini G, Sani C, Mazzotta A, Mantellini P, Ciatto S |
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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. Health technology Two faecal occult blood tests (FOBT) for colorectal cancer screening: Hemoccult (guaiac based) and reversed passive hemagglutination (RPHA) tests. RPHA tests were interpreted according to two different positivity thresholds.
Economic study type Cost-effectiveness analysis.
Study population Subjects aged 40-70 years.
Setting Hospital. Six municipalities in the province of Florence, Italy were involved in the screening. The economic study was carried out in Italy.
Dates to which data relate Subjects were recruited into the study during the period March 1992 to September 1995. 1996 costs were used for the assessment phase. The year for the remainder of the prices used in the analysis was not stated.
Source of effectiveness data The evidence for final outcomes was derived from a single study.
Link between effectiveness and cost data The costing was based on the same patient sample as that used in the effectiveness analysis, and appears to have been carried out retrospectively.
Study sample Power calculations were not used to determine the sample size. Subjects living in the six municipalities in the province of Florence (28,282 inhabitants aged 40-70) were enrolled in the study and underwent a double FOBT screening investigation. 8,353 subjects were recruited (3,887 men, mean age 54.2, 2,509 over the age of 49; 4.466 women, mean age 54.3, 2,906 older than 49). Screening with the double FOBT protocol was repeated after two years only in two of the six municipalities (7,982 subjects, aged 40-70). Overall mean compliance in the course of the study was 38.7%.
Study design The study was a prospective case-series which enrolled the population of six municipalities in the province of Florence, Italy.
Analysis of effectiveness The primary health outcome used in the analysis was the number of cancers/adenomas detected by the respective tests.
Effectiveness results Hemoccult, RPHA positive (+) and borderline (+/-), and RPHA (+ only) detected 16, 22 and 18 cancers and 124, 105 and 181 adenomas respectively. All of the 13 Dukes's A carcinomas were detected by RPHA (+ and +/-). Hemoccult and RPHA (+) detected six and nine Dukes's A cancers respectively. Curative polipectomy with no need for further surgery was obtained in two patients with a positive Hemoccult test, and in six with a positive (+) RPHA test. Three cancers were detected at repeat screening. All of them were Hemoccult negative; two were RPHA(+); one was RPHA (+/-).
Clinical conclusions RPHA (+ and +/-) showed the highest and RPHA (+ only) the lowest positivity rate at first screening. The Hemoccult positivity rate was highest at repeat screening. The authors concluded that screening by RPHA had higher efficacy in reducing CRC mortality and incidence.
Measure of benefits used in the economic analysis The measure of benefits used in the economic analysis was the number of cancers/adenomas detected by the respective tests.
Direct costs Only health services costs were considered. Each of three phases of the screening programme were costed: recruitment, screening and assessment. For the first two phases all relevant resources consumed by the programme were listed and measured. For staff costs the resource percentage attributable to the screening programme was apportioned. General expenses were calculated by dividing the total expense of the centre by the percentage of the total area currently occupied by the FOBT programme. The cost of the building was based on market rental prices. Costs for the recruitment phase included the resources for general organisation and direction of the programme. To calculate the costs for the assessment phase, National Tariffs for 1996 were used. The year for the rest of the prices was not stated. Resource quantities were not reported separately from the prices.
Currency US dollars ($), converted from Italian lira at an exchange rate of $1 to 1,550 Italian lira.
Sensitivity analysis In a sensitivity analysis an additional evaluation of the costs of the assessment phase was made according to the estimates of the mean costs of endoscopic examinations and treatments carried out by a working group.
Estimated benefits used in the economic analysis Hemoccult, RPHA positive (+) and borderline (+/-), and RPHA (+ only) detected 16, 22 and 18 cancers and 124, 105 and 181 adenomas respectively. All of the 13 Dukes's A carcinomas were detected by RPHA (+ and +/-). Hemoccult and RPHA (+) detected six and nine Dukes's A cancers respectively. Three cancers were detected at repeat screening. All of them were Hemoccult negative; two were RPHA(+); one was RPHA (+/-).
Cost results At the first screening round RPHA (+ and +/-) was the most costly ($136,120 per 10,000 screened subjects with 38.7% attendance rate) as the higher recall rate resulted in the highest cost for the assessment phase. RPHA (+) was the least expensive test in all programme phases ($96,770). Hemoccult was in an intermediate position for total and assessment costs but was the most costly test for the screening phase (total cost was $120,640). At repeat screening and in subjects aged 40-49 the total costs were lower than at the first screening owing to the lower positivity and recall rate. At first screening RPHA (+ and +/-) had the highest cost for each screened subject ($35.1) and RPHA (+) the lowest ($25).
Synthesis of costs and benefits Hemoccult showed the highest costs for each subject with detected cancer or adenomas ($12,900). RPHA(+) had the lowest cost for detected cancer ($9,020), whereas RPHA (+ and +/-) had the lowest cost for each subject with adenoma(s) ($1,780). Costs for each subject screened decreased at the second round ($25.1) or in younger subjects ($20.6 - $27.1). The cost for each subject with cancer or adenoma(s), however, increased at the second round ($18,990 and $3,450 respectively) and for younger subjects. When the working group's cost estimates were used, rather than ministerial tariffs, the overall assessment costs at first screening were increased by about 25%.
When the working group's cost estimates for endoscopic costs were considered instead of national tariffs, costs for each screened subject, or for each subject with detected cancer or adenoma(s), increased by 16% for Hemoccult, by 17% for RPHA (+ and +/-), or 10% for RPHA (+), in subjects aged 50-70 at first screening. The group's estimates of assessment costs caused smaller increases of costs at first screening in subjects aged 40-49 and an increase of 11% at repeat screening. With higher compliance rates, costs for each screened subject or each detected cancer or adenoma(s) would be lower, though a great improvement in compliance would be needed to lower total costs markedly.
Authors' conclusions Screening for colorectal cancer by an immunochemical FOBT based on RPHA is more cost effective than guaiac testing. Further efforts should be concentrated on the evaluation of RPHA sensitivity for colorectal cancer to assess the optimal positivity threshold. The analysis confirmed that screening for colorectal cancer under the age of 50 is not cost-effective.
CRD COMMENTARY - Selection of comparators A justification was given for the comparators used: all of the alternative screening procedures have been used in screening programmes that were effective in reducing colorectal cancer mortality. You should consider whether these are widely used health technologies in your own setting.
Validity of estimate of measure of benefit The estimate of the measure of benefit used in the economic analysis is likely to be internally valid.
Validity of estimate of costs Resource quantities were not reported separately from the prices but adequate details of cost estimation were given.
Other issues The issue of generalisability to other settings or countries was not addressed.
Source of funding Partially supported by the National Research Council - Applied Project Applicazioni Cliniche della Ricerca Oncologica, Grant No 96.00731. PF39.
Bibliographic details Castiglione G, Zappa M, Grazzini G, Sani C, Mazzotta A, Mantellini P, Ciatto S. Cost analysis in a population based screening programme for colorectal cancer: comparison of immunochemical and guaiac faecal occult blood testing. Journal of Medical Screening 1997; 4(3): 142-146 Indexing Status Subject indexing assigned by NLM MeSH Adult; Aged; Colorectal Neoplasms /prevention & Costs and Cost Analysis; Feces; Female; Hematologic Tests; Humans; Immunochemistry; Male; Mass Screening /economics /methods; Middle Aged; control AccessionNumber 21998006188 Date bibliographic record published 28/02/1999 Date abstract record published 28/02/1999 |
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