Faecal occult blood testing for population health screening May 2004

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Key assumptions used in the economic model • The economic model is designed to assess the relative cost-effectiveness of various FOBTs used to detect CRC in a screening population. Consequently, head-to-head comparisons between FOBTs are made. It is not intended that decision-makers compare tests not appearing directly alongside one another. • The natural progression of CRC is defined such that patients with undiagnosed cancer pass sequentially through each clinical stage after an appropriate time interval. Patients do not ‘skip’ stages in the sequential sequence. • Individuals with diagnosed CRC are at greatest risk of mortality for the first 5 years following diagnosis. These individuals are assumed to revert to a ‘normal’ lifeexpectancy if they survive their first 5 years with diagnosed cancer. • The likelihood of CRC detection with FOBT, or procedures used later in the diagnostic work-up, is assumed to be independent of the stage of cancer. • It is assumed that the presence or absence of dietary restrictions is the key determinant of differences in participation rates for the two classes of FOBTs (guaiac and immunochemical). • Participation in a screening program is assumed to remain constant despite arguments that the increased community awareness associated with a general population health screening program may lead to improved participation. • Participation in a screening program is assumed to be dependent on past behaviour. That is, future patterns of participation are affected by behaviour in previous rounds. • Individuals with increased risk of CRC, through family history for example, are not treated as part of the screening population. Similarly, symptomatic patients are treated as external to the general screening population. These individuals are treated as external due to the different diagnostic pathway they are subject to. • All individuals in the economic model are treated as having a maximum lifeexpectancy of 100 years. • For simplicity, indirect/societal costs are not included in the economic model, as they are likely to be negligible in the context of the total cost of the screening program. This assumption is consistent with other models in the literature. • The results of the economic model are presented in terms of the incremental cost per life-year gained with one screening program over another. • A discount rate of 5% per annum was applied to all costs and health outcomes. 34
The literature on FOBT screening for colorectal cancer FOBT has been repeatedly shown to be a cost-effective screening option for CRC in the general population (Wagner et al 1996; Khandker et al 2000; Salkeld et al 1996; Bolin et al 1999; O’Leary et al 2004). Although studies in the literature utilise a wide range of assumptions and screening populations, the majority of studies favour FOBT screening over no screening. There are a limited number of studies that have been conducted within the Australian setting. Again, these tend to show FOBT to be a cost-effective method in screening for CRC. In these Australian studies, Salkeld et al (1996) estimate the cost-effectiveness of annual FOBT screening as $24,660 per life-year gained, Bolin et al (1999) estimate the cost-effectiveness of annual FOBT screening as $36,132 per life-year gained and O’Leary et al (2004) give an estimate of $46,900. Note that while the methodologies and assumptions used in these studies vary greatly, the results provide good evidence of FOBT being a cost-effective method of CRC screening. Studies to date have focused on the incremental cost-effectiveness of FOBT screening versus no screening and a comparison between the available FOBTs has not yet been conducted. Patient population used in the economic model Individuals from the general population are invited to be screened for CRC under the proposed program. They are selected based on age alone and other risk factors do not play a role. Individuals identified as being at heightened risk (possibly due to a family history of CRC), are not included in the screening program and will instead undergo a separate diagnostic work-up. The age of the eligible population is treated as exogenous in the economic model. Annual and biennial screening intervals are tested and the most cost-effective alternative is recommended based on the results. Structure of the economic model A Markov model with Monte Carlo simulations is used to follow a sample of 20,000 patients through the FOBT screening program from the first invitation for screening until either death or ineligibility due to age. The timing of the first invitation to screening is dependent on the characteristics of the screening program and is to be determined by the results of the economic model, as is the interval between screening rounds. The model consists of two modelled components: • the natural history of CRC (see Figure 2), which determines how patients progress through various health states; and • the screening pathway (see Figure 3), which aims to intercept the natural progression of CRC in such a way that treatment can be initiated and life-expectancy increased. Individuals in the model are advanced through the Markov process in 3-monthly cycles until death. Faecal occult blood testing 35
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 12 and 13: The head-to-head studies examining
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: subject to verification bias due to
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
Page 63 and 64: Following diagnosis of CRC, patient
Page 65 and 66: In the case of Hemoccult Sensa, col
Page 67 and 68: Of the two tests, Hemoccult Sensa d
Page 69 and 70: Table 31 Life-expectancy from the b
Page 71 and 72: • The frequency of screening has
Page 73 and 74: Additionally, for both FOBTs, incre
Page 75 and 76: screening are higher, the differenc
Page 77 and 78: Conclusions Safety Faecal occult bl
Page 79 and 80: The incremental cost per life-year
Page 81: Summary of outcomes The Medical Ser
Page 84 and 85: Professor Bryant Stokes Neurologica
Page 86 and 87: Professor Graeme Young MBBS MD FRAC
Page 88 and 89: Specificity carcinoma Sensitivity c
Page 90 and 91: Appendix D Literature searches Medl
Page 92 and 93: Search history Results 26 hemeselec
Page 94 and 95: 10. Bech K, Kronborg O, Fenger C (1
Page 96 and 97: 33. Foliente RL, Wise GR, Collen MJ
Page 98 and 99: 56. Hart AR, Barone TL, Gay SP, Ing
Page 100 and 101:
79. Kronborg O, Fenger C, Olsen J,
Page 102 and 103:
102. Lynch NM, McHutchison JG, Youn
Page 104 and 105:
125. Nakama H, Fattah A, Zhang B, U
Page 106 and 107:
148. Rasmussen M, Fenger C, Kronbor
Page 108 and 109:
169. Scholefield JH, Moss S, Sufi F
Page 110 and 111:
192. Walker AR, Whynes DK, Hardcast
Page 112 and 113:
Appendix F Positive predictive valu
Page 114 and 115:
Table 42 Meta-analyses of PPV for c
Page 116 and 117:
Table 43 Meta-analyses of PPV for n
Page 118 and 119:
Appendix G Diagnostic odds ratios A
Page 120 and 121:
Figure 10 Summary receiver-operatin
Page 122 and 123:
Appendix I Participation in FOBT sc
Page 124 and 125:
Appendix J Relative cost-effectiven
Page 126 and 127:
Number detected by screening or sym
Page 128 and 129:
Appendix K Sensitivity analysis of
Page 130 and 131:
Abbreviations AACR Australasian Ass
Page 132 and 133:
References Aisawa T, Saito H, Kawag
Page 134 and 135:
Hardcastle JD, Armitage NC, Chamber
Page 136 and 137:
Rae AJ, Cleator IGM (1994), The two
Page 138:
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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