Table 1:
Model Inputs: Test characteristics and participation assumptions associated with colorectal cancer screening.
| TEST CHARACTERISTICS | |
| Specificity and sensitivity of FITa | |
| Specificity (per person) | 96.7% |
| Sensitivity adenoma 1–5mm | 0.0% |
| Sensitivity adenoma 6–9mm | 17.6% |
| Sensitivity adenoma 10+ mm | 34.0% |
| Sensitivity cancer long before clinical diagnosis | 29.5% |
| Sensitivity cancer shortly before clinical diagnosisb | 66.0% |
| Specificity and sensitivity of colonoscopyc,d | |
| Specificity | 86% |
| Sensitivity adenoma 1–5mm | 75% |
| Sensitivity adenoma 6–9mm | 85% |
| Sensitivity adenoma 10+ mm | 95% |
| Sensitivity preclinical cancer | 95% |
| Complication of colonoscopye | |
| Fatal perforationf | 0.0074% |
| Bleedingg | 0.1640% |
| Perforationg | 0.0850% |
| Otherh | 0.3310% |
| PARTICIPATION | |
| Participation in previous screening episodes | |
| No prior screening | 0% |
| Some prior screening | 25% |
| Reasonable prior screening | 50% |
| Most prior screening | 75% |
| Perfect prior screening | 100% |
| Colonoscopy 10 years prior | 0% |
| Colonoscopy 15 years prior | 0% |
| Participation in current screening episode | 100% |
| Participation with diagnostic colonoscopyi | |
| Males | 79% |
| Females | 78% |
| Participation in surveillanceJ | 80% |
Abbreviations: FIT = faecal immunochemical test
Specificity and sensitivity of FIT derived from data from the Dutch colorectal cancer screening program15 and were adjusted to an overall positivity of 7.5% which equated to a cut-off level of 23 μg Hb/g feces
We assume that faecal screening is more sensitive in cancers towards the end of the occult bleeding period as they progress towards becoming symptomatic (i.e. visible bleeding) and clinically detectable23
Specificity for colonoscopy is based on Schroy et al, 2013.20 The lack of specificity with endoscopy reflects the detection of non-adenomatous lesions, which, in the case of colonoscopy leads to unnecessary polypectomy, which is associated with an increased risk complications
Sensitivity of colonoscopy for the detection of adenomas and CRC within the reach of the endoscope was obtained from a systematic review on miss rates observed in tandem colonoscopy studies19
Complications are conditional on polypectomy, and we assume that polypectomy is only performed if colonoscopy is positive
Risk of dying from colonoscopy were based on Canadian literature.22 A death was attributed to colonoscopy if it occurred within 30 days following an index colonoscopy.
Complications of colonoscopy were based on Canadian literature.21, 22 A complication is considered as individuals who were admitted to hospital with colonoscopy related events during the 30 days following the index colonoscopy
Other events include post-polypectomy syndrome, cardiac events, syncope/hypotension, gastrointestinal symptoms, splenic/hepatic hematoma, fall/injury, thrombophlebitis, hyponatremia, oesophageal variceal haemorrhage, and various other symptoms
The participation with diagnostic colonoscopy after a positive faecal test is taken from Cancer Quality Council of Ontario13 and is the same for all screening scenarios except under the assumption of perfect adherence to screening
The participation rate for colonoscopy surveillance was assumed to be 80%, based on data from US clinical practice 14 and is the same for all screening scenarios except under the assumption of perfect adherence to screening where we assume 100% adherence to surveillance