Table 1. Parameter estimates, with base-case values, ranges and distributions.
| Model parameter | Base-case | Range for SA | Distribution for PSAa | Source |
|---|---|---|---|---|
| Performance of screening tests | ||||
| gFOBT sensitivity for adenomas | 11% | 10–12% | Beta (11.40, 92.10) | Allison et al, 1990; Castiglione et al, 1991; Foley et al, 1992; Allison et al, 1996; Brevinge et al, 1997; Lieberman and Weiss, 2001; Niv et al, 2002; Sung et al, 2003 Collins et al, 2005 |
| gFOBT sensitivity for CRC | 36% | 31–42% | Beta (105.00, 186.60) | |
| gFOBT specificity for adenomas and CRC | 97% | 96–98% | Beta (1083.40, 33.50) | |
| FIT sensitivity for adenomas | 21% | 19–22% | Beta (594.62, 2236.92) | Allison et al, 1996; Itoh et al, 1996; Chen et al, 1997; Nakama et al, 2000; Nakama et al, 2001; Cheng et al, 2002; Gondal et al, 2003; Liu et al, 2003; Morikawa et al, 2005; Nakazato et al, 2006; Allison et al, 2007; Morikawa et al, 2007 |
| FIT sensitivity for CRC | 71% | 67–75% | Beta (35.29, 143.08) | |
| FIT specificity for adenomas and CRC | 95% | 94–96% | Beta (1732.57, 91.19) | |
| FSIG sensitivity for low-risk distal adenomas | 65% | 60–70% | Beta (235.00, 126.54) | Expert opinion informed by Rozen et al, 1987; Lieberman and Weiss, 2001; Sung et al, 2003 |
| FSIG sensitivity for intermediate/high-risk distal adenomas | 74% | 68–78% | Beta (180.00, 63.24) | |
| FSIG sensitivity for distal CRC | 90% | 85–95% | Beta (90.00, 10.00) | |
| FSIG specificity for distal adenomas and CRC | 92% | 90–95% | Beta (250.00, 21.74) | |
| Uptake and compliance with screening and diagnostic tests | ||||
| gFOBT uptake | 53% | 32–70% | Uniform (32%, 70%) | Weller et al, 2006; Information Services Division, 2008 |
| FIT uptake | 53% | 32–70% | Uniform (32%, 70%) | |
| FSIG uptake | 39% | 24–67% | Uniform (24%, 67%) | UK Flexible Sigmoidoscopy Screening Trial Investigators, 2002 |
| % of individuals who never accept an offer of screeningb | 13% | 0–41% | — | Weller et al, 2006 |
| COL compliance (diagnostic test) | 86% | 81–90% | Uniform (81%, 90%) | Weller et al, 2006; Information Services Division, 2008 |
| Performance of diagnostic tests and related parameters | ||||
| COL sensitivity for low-risk adenomas | 77% | 73–80% | Beta (350.00, 104.55) | van Rijn et al, 2006 Bressler et al, 2007 |
| COL sensitivity for intermediate/high-risk adenomas | 98% | 93–99% | Uniform (93%, 99%) | |
| COL sensitivity for CRC | 98% | 95%–99% | Uniform (95, 99%) | |
| COL specificity for adenomas and CRC | 97% | 96–98% | Beta (970.00, 30.00) | Expert opinion |
| CTC sensitivity for low-risk adenomas | 53% | 45–60% | Beta (80.00, 70.94) | Expert opinion, informed by Cotton et al, 2004; Halligan et al, 2005; Mulhall et al, 2005; Johnson et al, 2008 |
| CTC sensitivity for intermediate/high-risk adenomas | 85% | 48–100% | Beta (4.50, 0.79) | |
| CTC sensitivity for CRC | 85% | 75–95% | Beta (50.00, 8.82) | |
| CTC specificity for adenomas and CRC | 86% | 80–90% | Beta (140.00, 22.79) | |
| Average number of adenomas removed per person | 1.9 | — | — | Winawer et al, 1993 |
| Surveillance of screening-detected adenomas | ||||
| % of those in with intermediate/high-risk adenomas removed in whom the adenoma was high-risk | 29% | — | — | Alexander and Weller, 2003; Weller et al, 2006 |
| COL compliance (surveillance) | 86% | 81–90% | Uniform (81%, 90%) | Assumption based on Weller et al, 2006; Information Services Division, 2008 |
| Harms of screening | ||||
| FSIG probability of perforation (with or without polypectomy) | 0.002% | 0–0.051% | Uniform (0%, 0.051%) | UK Flexible Sigmoidoscopy Screening Trial Investigators, 2002 |
| FSIG probability of death following perforation | 6.452% | 0–9.070% | Uniform (0%, 9.070%) | Gatto et al (2003) |
| Probability of (major) bleeding following FSIG | 0.029% | 0.002–0.054% | Uniform (0.002%, 0.054%) | UK Flexible Sigmoidoscopy Screening Trial Investigators, 2002 |
| COL probability of perforation (with polypectomy) | 0.216% | 0.168–0.298% | Uniform (0.168%, 0.298%) | Dafnis et al, 2001 |
| COL probability of perforation (without polypectomy) | 0.107% | 0.010–0.249% | Uniform (0.010%, 0.249%) | |
| COL probability of death following perforation | 5.195% | 0–9.070% | Uniform (0%, 9.070%) | Gatto et al (2003) |
| Probability of (major) bleeding following COL | 0.379% | 0.065–0.412% | Uniform (0.065%, 0.412%) | UK Flexible Sigmoidoscopy Screening Trial Investigators, 2002 |
| Health-related QoL | ||||
| Utility: cancer free | 0.94 | — | — | Fryback and Lawrence (1997) |
| Utility: stage I, II, III, IV cancer | 0.80 | 0.43–0.94 | 0.94*Beta (3.92, 0.69) | Ramsey et al (2000) |
| Costs | ||||
| gFOBT kitc | €1.70 | €1.36–€2.04 | Uniform (€1.36, €2.04) | Estimated by authors |
| gFOBT processing/analysisd | €7.81 | €6.25–€9.37 | Uniform (€6.25, €9.37) | |
| FIT kitc | €3.75 | €3–€4.50 | Uniform (€3, €4.50) | |
| FIT processing/analysisd | €11.60 | €9.28–€13.92 | Uniform (€9.28, €13.92) | |
| Cost of FSIG (with/without polypectomy) | €150 | €120–€180 | Uniform (€120, €180) | Whynes et al, 2003; VHI Healthcare |
| Cost of COL | €650 | €520–€780 | Uniform (€520, €780) | HSE Casemix Unit, 2008 |
| Cost of CTC | €550 | €440–€660 | Uniform (€440, €660) | Expert opinion |
| Cost of treating bowel perforation | €10 200 | €8160–€12 240 | Uniform (€8160, €12 240) | HSE Casemix Unit, 2008 |
| Cost of admittance for bleeding | €3079 | €2463–€3695 | Uniform (€2463, €3695) | |
| Pathology cost for adenoma | €65 | €52–€78 | Uniform (€52, €78) | Tappenden et al, 2004 |
| Pathology cost for cancer | €530 | €424–€636 | Uniform (€424, €636) | |
| Lifetime cost stage I CRC-symptomatic | €23 688 | €18 950–€28 425 | Uniform (€18 950, €28 425) | Tilson et al, 2011 |
| Lifetime cost stage II CRC-symptomatic | €37 180 | €29 744–€44 616 | Uniform (€29 744, €44 616) | |
| Lifetime cost stage III CRC-symptomatic | €48 835 | €39 068–€58 602 | Uniform (€39 068, €58 602) | |
| Lifetime cost stage IV CRC-symptomatic | €36 602 | €29 281–€43 922 | Uniform (€29 281, €43 922) | |
| Lifetime cost stage I CRC-screen-detected | €22 885 | €18 308–€27 462 | Uniform (€18 308, €27 462) | |
| Lifetime cost stage II CRC-screen-detected | €36 377 | €29 102–€43 652 | Uniform (€29 102, €43 652) | |
| Lifetime cost stage III CRC-screen-detected | €48 032 | €38 426–€57 638 | Uniform (€38 426, €57 638) | |
| Lifetime cost stage IV CRC-screen-detected | €35 799 | €28 639–€42 959 | Uniform (€28 639, €42 959) | |
| Discount rate | ||||
| Discount rate for costs and benefits | 4% | 0–6% | — | Recommended for Ireland |
Abbreviations: COL=colonoscopy; CRC=colorectal cancer; CTC=CT colonography; FIT=faecal immunochemical test; FSIG=flexible sigmoidoscopy; gFOBT=guaiac-based faecal occult blood test; PSA=probabilistic sensitivity analysis; SA=sensitivity analysis; low-risk adenoma(s), <10 mm; intermediate/high-risk adenoma(s), ⩾10 mm.
a
if no distribution given, parameter was not varied in the PSA.
b
relevant to gFOBT and FIT scenarios only.
c
cost per kit dispatched (i.e., cost per individual invited to participate in screening).
d
cost per kit completed and returned (i.e., cost per screening participant).