|
The two tier fecal occult blood test: cost-effective screening |
Rae A J, Cleator I G |
|
|
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-tier fecal occult blood test which is a strategy combining HO Sensa guaiac test and a hemoglobin-specific Hemeselect test when the result of the former is positive.
Economic study type Cost-effectiveness analysis
Study population The study population included males and females 40 years of age or older. Patients were at high risk, asymptomatic, symptomatic or expressed some personal or family history of gastrointestinal disorders.
Setting The study was conducted partly in the hospital and partly in the primary care setting. The economic study was carried out in Canada.
Dates to which data relate Dates are not given in the study.
Source of effectiveness data Link between effectiveness and cost data Costs and effectiveness were analysed for the same patient population. Costs data were collected retrospectively.
Study sample The first arm of the study enrolled 573 high risk patients. The second arm of the study enrolled 1301 patients, 52% asymptomatic and 48% symptomatic. It was not stated whether power calculations determined the sample size.
Study design It is not clear whether the study was a RCT, but it appears to be a nonrandomised trial with concurrent controls. The study was multi-centre. Technicians were blinded to physician's observations and in the case of the two-tier test to the results of the first test when analysing the second test. Drop out rate was not specified.
Analysis of effectiveness The analysis was based on treatment completers only. Patients were stratified according to personal history and symptoms. The outcome measures studied were false positive rate, sensitivity and specificity rates.
Effectiveness results In the high risk group specificity was 88.7%, 80.6%, and 69.5% for two-tier, Hemoccult and HO Sensa respectively and false positive rates were 11.3%, 19.5% and 30.5% for the three tests respectively (95% CI for all colorectal cancers and polyps greater than 1 cm, alpha=0.05).
In the second arm of the study specificity was 96.8%, 87.2% and 69.5% for the 3 tests respectively, while false positive rates were 3.2%, 12.8% and 22.3% respectively (95% CI for all CRCs and polyps greater than 1 cm). No significant differences in sensitivity were observed between tests in the same group.
Clinical conclusions The two-tier test produced fewer false positives than traditional tests.
Measure of benefits used in the economic analysis The benefit measure used in the economic analysis was the number of cancers detected. In the high risk group the number of adenomas and polyps greater than 1 cm were also considered.
Direct costs Only health service costs were considered. Costs of tests and colonoscopy and costs of colonoscopy complications were included including surgery and hospital stay to repair colonoscopy perforations.
Some quantities and costs were analysed separately. Cost estimates were based on actual data (units of analysis). Price date was not specified.
Sensitivity analysis No sensitivity analysis was performed.
Estimated benefits used in the economic analysis In the high risk group, the number of cancers detected were 19 for Hemoccult, Hemeselect and two-tier tests and 20 for HO Sensa. And the number of adenomas and polyps greater than 1.0 cm, detected were 22 for Hemoccult, 24 for HO Sensa, 22 for Hemeselect and 17 for the two-tier test.
In the second arm of the study HO Sensa detected 3 cancers versus 2 in all other tests, in the symptomatic group. In the asymptomatic sub-group, Hemoccult did not pick up any cancer whereas the other 3 tests detected 1 cancer.
Cost results In the high risk group (n=573), total costs for Hemoccult, HO Sensa, Hemeselect and two-tier test were $44,865, $63,512, $47,223 and $34,991 respectively.
In the second arm of the study (n=1077), total costs (symptomatic and asymptomatic groups combined) were $50,355 (Hemoccult), $81,494 (HO Sensa), $41,895 (Hemeselect) and $21,650 (two-tier).
Synthesis of costs and benefits In the high-risk group cost per cancer detected was $2,361 for Hemoccult, $3,176 for HO Sensa, $2,485 for Hemeselect and $1,842 for the two-tier test.
Cost per cancer and adenomas/polyps > 1 cm detected was $1,094, $1,444, $1,152 and $972 for Hemoccult, HO Sensa, Hemeselect and Two-tier test respectively.
In the second arm of the study, cost per cancer detected was $25,178, $27,165, $20,948 and $10,825 for the 4 tests respectively. In the asymptomatic group analysis the ratios were $95,585, $16,422, $5,476 for Ho Sensa, Hemeselect and two-tier respectively. Incremental analysis was not performed.
Authors' conclusions The authors concluded that fewer false positives and thus fewer resultant diagnostic work-ups place the two-tier test in the position of the most cost-effective FOBT among the tests studied. Since it was cost-effective even for the analysis of asymptomatic patients sub-group, it is suitable for screening normal populations.
CRD Commentary No sensitivity analysis was performed. Missed cancers and ability to detect polyps represent open issues with the two-tier test, as the authors noted. No power calculations were given. An incremental analysis, where suitable could have been useful in order to justify the conclusion.
Implications of the study The area of clinical effectiveness needed more investigation.
Bibliographic details Rae A J, Cleator I G. The two tier fecal occult blood test: cost-effective screening. Canadian Journal of Gastroenterology 1994; 8(6): 362-368 Indexing Status Subject indexing assigned by CRD MeSH Cost-Benefit Analysis; Feces; Female; Gastrointestinal Diseases; Gastrointestinal Hemorrhage; Gastrointestinal neoplasms; Male; Occult Blood AccessionNumber 21995000027 Date bibliographic record published 26/06/1995 Date abstract record published 26/06/1995 |
|
|
|