Faecal occult blood testing for population health screening May 2004

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The head-to-head studies examining the relative performance of different FOBTs identified in this assessment did not report any safety data. Therefore, the performance of alternative FOBTs for population health screening cannot be assessed on the basis of safety data. Effectiveness Three head-to-head studies estimated the sensitivity and specificity of various FOBTs using the interval cancer rate (ie, the number of cancers that are detected during intervals between screening) as a proxy for the false negative rate. This allowed calculation of the relative sensitivities and specificities for each of the FOBTs included in these studies. Slightly more studies reported data that enabled calculation of the relative true positive rate (TPR) and the relative false positive rate (FPR) (ie, the ratio of one test’s TPR or FPR to the other) of the FOBTs compared. There were no studies of a suitable quality available to enable assessment of the relative accuracy of the different FOBTs for the detection of adenomas. On the basis of two of these studies, HemeSelect was found to be significantly more sensitive than Hemoccult in detecting carcinoma (77.1% vs 30.0%, respectively; risk difference (RD) 0.46; 95% confidence interval (CI): 0.231, 0.631). In contrast, the Hemoccult test was significantly more specific than HemeSelect (97.8% vs 93.5%, respectively; RD –0.043; 95% CI: –0.070, –0.026). This finding was maintained in a sensitivity analysis incorporating a study conducted in a population with a high proportion of subjects that were at increased risk. Similarly, the TPR was significantly in favour of RPHA (HemeSelect and Immudia-HemSp pooled) rather than Hemoccult (relative TPR 0.59; 95% CI: 0.39, 0.88), whereas the FPR of Hemoccult was lower than that for RPHA (relative FPR 0.53; 95% CI: 0.33, 0.87). Therefore, HemeSelect was more effective than Hemoccult at detecting patients with CRC but was not as effective at excluding participants without the disease. The practical impact of this trade-off cannot be determined by the sensitivity and specificity values alone and has been investigated via the use of an economic model in the cost-effectiveness section of this assessment report. In a single study, the sensitivity of Hemoccult and Fecatwin Sensitive/Feca EIA were not significantly different (50.0% vs 83.3%, respectively; RD 0.33; 95% CI: –0.166, 0.832). However, Hemoccult was significantly more specific than Fecatwin Sensitive/Feca EIA (97.1% vs 92.2%, respectively; RD –0.049; 95% CI: –0.066, –0.032). This means that at this time there is no statistically significant evidence to suggest that Hemoccult or Fecatwin Sensitive/Feca EIA are better at identifying patients with CRC. However, there is statistically significant evidence to suggest that Hemoccult is superior at excluding participants without the disease. Similarly, the TPR was not significantly different when Hemoccult was compared to Fecatwin Sensitive/Feca EIA (relative TPR 0.60; 95%CI: 0.14, 2.51). However, the FPR of Hemoccult was significantly lower than Fecatwin Sensitive/Feca EIA (relative FPR 0.35; 95% CI: 0.24, 0.51). Therefore, based on these limited data, Hemoccult was statistically more accurate than Fecatwin Sensitive/Feca EIA, when used for population health screening. It should be noted, however, that the subjects in this study were not required to adhere to the dietary restrictions generally recommended with the use of a guaiac FOBT. The sensitivity of Hemoccult Sensa and HemeSelect were not significantly different (79.4% vs 68.8%, respectively; RD –0.107; 95% CI: –0.317, 0.103), based on data from a single study. In contrast, HemeSelect proved to be significantly more specific than xii Faecal occult blood testing
Hemoccult Sensa (94.4% vs 86.7%, respectively; RD 0.077; 95% CI: 0.068, 0.086). These results were maintained in a sensitivity analysis incorporating a study conducted in a population with a high proportion of subjects that were at increased risk. Similarly, the TPR was not significantly different when Hemoccult Sensa was compared with HemeSelect (relative TPR 1.07; 95%CI: 0.70, 1.62). However, the FPR of HemeSelect was lower than that of Hemoccult Sensa (relative FPR 2.23; 95% CI: 1.14, 4.37). This means that at this time there is no statistically significant evidence to suggest that Hemoccult Sensa or HemeSelect are better at identifying patients with CRC. However, there is statistically significant evidence to suggest that HemeSelect is superior at excluding participants without the disease. Therefore, based on these limited data, HemeSelect was statistically more accurate than Hemoccult Sensa, when used for population health screening. Newer immunochemical tests are currently commercially available. Other FOBTs with similar technical characteristics (ie, in vitro diagnostic accuracy for the detection of haemoglobin) may provide similar outcomes to those of HemeSelect. However, there is currently a lack of evidence for this and the performance of other immunochemical tests in the context of population health screening for CRC remains to be determined. It is important to note that the measures of the sensitivity and specificity of the FOBTs for the detection of CRC varied considerably between studies conducted in different populations. In addition, estimates of these measures differed significantly between different tests of the same class. Therefore, relative findings for any individual pairs of guaiac and immunochemical tests cannot be generalised across comparisons and findings for any individual test do not represent all tests of that class. A modelled economic evaluation was used to determine the effectiveness and costeffectiveness of the different tests in a population screening setting. This model was built upon the sensitivity and specificity data summarised above and was able to determine the broader population-wide impact of the sensitivity and specificity of these tests. Cost-effectiveness An economic model was designed to assess the relative cost-effectiveness of various FOBTs used to detect CRC in a population health screening setting. Consequently, headto-head comparisons between FOBTs are made. It is not intended that decision-makers compare tests not compared head-to-head within the economic model. The base-case scenario assumes biennial screening in individuals aged 55–74 years. The economic model indicates that FOBTs with greater sensitivity for colorectal neoplasia detection will offer better overall survival outcomes. A key driver of the difference in the total cost associated with the FOBTs is the specificity. Tests with lower specificities are associated with higher diagnostic follow-up costs due to the increased levels of resource wastage. The model attempts to present the trade-off between these values in an economic context by providing estimates of the incremental cost per lifeyear gained for each pair of tests compared. The incremental cost per life-year gained of HemeSelect was $3172 in a comparison against Hemoccult, and $21,533 for Hemoccult Sensa in a comparison against HemeSelect. These findings should, however, be constrained to the context of the headto-head data upon which they are based. That is, the magnitude of the difference in the Faecal occult blood testing xiii
Page 1 and 2: Faecal occult blood testing for pop
Page 3 and 4: Contents Executive summary.........
Page 5 and 6: Tables Table 1 Hierarchy of evidenc
Page 7: Figures Figure 1 Reasons for exclus
Page 10 and 11: BM-Test Colon Albumin. HemeSelect a
Page 14 and 15: sensitivity between tests contains
Page 17 and 18: Introduction The Medical Services A
Page 19 and 20: The guaiac FOBTs include brand name
Page 21 and 22: Classification of CRC may be by one
Page 23 and 24: Current reimbursement arrangement F
Page 25 and 26: Searches of the following secondary
Page 27 and 28: Identified by the search (n = 1214)
Page 29 and 30: Expert advice An advisory panel wit
Page 31 and 32: Trial Trial design Reviewed for eff
Page 33 and 34: eported (Robinson et al 1999). Of t
Page 35 and 36: unacceptable and unethical to subje
Page 37 and 38: Long-term follow-up Randomisation/
Page 39 and 40: Three different methods are used to
Page 41 and 42: • β j is a fixed effect which is
Page 43 and 44: Table 4 Meta-analyses of sensitivit
Page 45 and 46: Relative true positive rate and rel
Page 47 and 48: Table 7 Meta-analyses of relative F
Page 49 and 50: subject to verification bias due to
Page 51 and 52: The literature on FOBT screening fo
Page 53 and 54: Figure 3 Screening pathway used in
Page 55 and 56: Table 10 Prevalence used for indivi
Page 57 and 58: Table 15 and Table 16 outline the c
Page 59 and 60: Relevant sensitivity and specificit
Page 61 and 62: Table 22 Detection rates associated
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Following diagnosis of CRC, patient
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In the case of Hemoccult Sensa, col
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Of the two tests, Hemoccult Sensa d
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Table 31 Life-expectancy from the b
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• The frequency of screening has
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Additionally, for both FOBTs, incre
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screening are higher, the differenc
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Conclusions Safety Faecal occult bl
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The incremental cost per life-year
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Summary of outcomes The Medical Ser
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Professor Bryant Stokes Neurologica
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Professor Graeme Young MBBS MD FRAC
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Specificity carcinoma Sensitivity c
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Appendix D Literature searches Medl
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Search history Results 26 hemeselec
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10. Bech K, Kronborg O, Fenger C (1
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33. Foliente RL, Wise GR, Collen MJ
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56. Hart AR, Barone TL, Gay SP, Ing
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79. Kronborg O, Fenger C, Olsen J,
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102. Lynch NM, McHutchison JG, Youn
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125. Nakama H, Fattah A, Zhang B, U
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148. Rasmussen M, Fenger C, Kronbor
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169. Scholefield JH, Moss S, Sufi F
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192. Walker AR, Whynes DK, Hardcast
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Appendix F Positive predictive valu
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Table 42 Meta-analyses of PPV for c
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Table 43 Meta-analyses of PPV for n
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Appendix G Diagnostic odds ratios A
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Figure 10 Summary receiver-operatin
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Appendix I Participation in FOBT sc
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Appendix J Relative cost-effectiven
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Number detected by screening or sym
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Appendix K Sensitivity analysis of
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Abbreviations AACR Australasian Ass
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References Aisawa T, Saito H, Kawag
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Hardcastle JD, Armitage NC, Chamber
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Rae AJ, Cleator IGM (1994), The two
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Young GP, St John DJB, Winawer SJ,
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Faecal occult blood testing for population health screening May 2004

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