Table 1 Characteristics of included studies
StudyCountryNo of patientsNo of patients with CRC (%)SettingInvestigation usedConsecutive patientsBlinded?Quality level
Tate 198832UK13014 (10.8)Secondary careColonoscopyUnclearNo4
Bellentani 199026Italy25410 (3.9)Primary and secondary careColonoscopy or double-contrast barium enemaYesUnclear2*
Brenna 199033Norway31124 (7.7)Secondary careColonoscopyYesNo4
Berkowitz 199328South Africa30314 (4.6)Secondary careColonoscopyUnclearUnclear4
Neugut 199336USA93674 (7.9)Secondary careColonoscopyUnclearUnclear4
Brewster 199430UK46221 (4.5)Secondary careDouble-contrast barium enema and flexible sigmoidoscopyUnclearUnclear4
Steine 199429Norway184055 (3.0)Primary careDouble-contrast barium enemaYesYes1
Cheong 200035Malaysia29320 (6.8)Secondary careColonoscopyUnclearUnclear4
Morini 200127Italy36840 (10.9)Secondary careColonoscopyYesNo4
de Bosset 200231Switzerland85851 (5.9)Secondary careColonoscopyYesNo4
Selvachandran 200218UK226895 (4.2)Secondary careColonoscopy, double-contrast barium enema, or flexible sigmoidoscopyUnclearUnclear2*
Panzuto 200334Italy28041 (14.6)Primary careColonoscopy or double-contrast barium enemaYesUnclear2*
Ahmed 200516UK43935 (8.0)Population-basedColonoscopyYesUnclear4
Bjerregaard 200717Denmark2172122 (5.6)Secondary careColonoscopy, double-contrast barium enema, flexible sigmoidoscopy, or CT colographyYesUnclear4
Thompson 200719UK8529467(5.5)Secondary careFlexible sigmoidoscopyYesUnclear4
  • *Blinding in these studies was not stated explicitly, but they used separate researchers to collect symptom data from those who performed diagnostic tests, therefore their quality level is assumed to be 2 (see box 2).

  • CRC, colorectal carcinoma.