Table 2

Model parameters

VariableEstimate (range)DistributionSource
Residual adenoma prevalence at initial CRC diagnosis (most advanced lesion)12
 Adenoma 1–5 mm0.15 (0.11–0.20)Beta (35, 196)
 Adenoma 6–9 mm0.11 (0.08–0.16)Beta (26, 205)
 Adenoma 10 mm or larger0.04 (0.02–0.07)Beta (10, 221)
 Preclinical localised CRC0.001*Uniform (0, 0.002)
 Hyperplastic polyp 1–5 mm0.130 (0.09–0.18)Beta (30, 201)
 Hyperplastic polyp 6–9 mm0.048 (0.02–0.08)Beta (11, 220)
 Hyperplastic polyp 10 mm or larger0.013 (0.003–0.03)Beta (3, 228)
Test characteristics (person-based; for most advanced lesion)
Sensitivity (CTC)12
 Polyp 1–5 mm0.31 (0.17–0.47)†Beta (11, 24)
 Polyp 6–9 mm0.38 (0.21–0.57)Beta (10, 16)
 Polyp 10 mm or larger, or CRC0.80 (0.52–0.97)Beta (8, 2)
Specificity (CTC)0.84 (0.78–0.89)Beta (134, 26)12
Sensitivity (OC)
 Polyp 1–5 mm0.55 (0.45–0.64)Beta (56, 46)29
 Polyp 6–9 mm0.67 (0.54–0.79)Beta (35, 17)28
 Polyp 10 mm or larger, or CRC0.95 (0.84–1.00)Beta (21, 1)28
Specificity for adenomas (OC)1.00Assumed constant
Colonoscopy risks (per 1000 polypectomies)
Death0.033 (0.00003–0.166)Beta (0.493, 14 994)30 31
Nonfatal perforation0.60 (0.36–0.91)Beta (18, 29 988)30
GI bleed6.66 (5.77–7.61)Beta (201, 29 988)30
Quality-of-life weights
Utilities32
 Localised cancer0.74 (0.69–0.79)Normal (0.74, 0.026)
 Regional cancer0.63 (0.58–0.68)Normal (0.11, 0.008)‡
 Distant cancer0.25 (0.20–0.30)Normal (0.25, 0.026)
Disutility33
 Perforation or GI bleed0.038 (0.001–0.075)Uniform (0.001, 0.075)
Costs
Tests13
 OC without polypectomyUS$700 (US$684–US$717)Normal (700, 8.2)
 OC with polypectomyUS$1033 (US$930–US$1156)Normal (1033, 60.7)
 CTCUS$244 (US$228–US$275)Normal (244, 7.7)
Colonoscopy complications34
 PerforationUS$14 949 (US$12 019–US$17 879)Normal (14949, 1494.9)
 Serious gastrointestinal eventUS$6256 (US$4849–US$7213)Normal (6256, 625.6)
Cancer care34 35
 Initial year, localised CRCUS$33 629 (US$32 745–US$34 538)LN (10.42, 0.0136)
 Initial year, regional CRCUS$48 053 (US$47 065–US$49 062)LN (10.78, 0.0106)
 Initial year, distant CRCUS$66 327 (US$63 375–US$47 301)LN (11.00, 0.0188)
 Continuing, localised CRCUS$2352 (US$2071–US$2483)LN (7.76, 0.0463)
 Continuing, regional CRCUS$2912 (US$2573–US$3063)LN (7.98, 0.0445)
 Continuing, distant CRCUS$9920 (US$8489–US$10 638)LN (9.20, 0.0576)
 Death from distant CRCUS$76 310 (US$74 555–US$78 086)LN (11.24, 0.0119)
  • *Assumption.

  • †Assumed to be 0 in base case.

  • ‡Models the difference between the utility of localised and regional CRC.

  • CRC, colorectal cancer; CTC, CT colonography; GI, gastrointestinal; LN, Lognormal; OC, optical colonoscopy.