Diagnostic accuracy of immunochemical versus guaiac faecal occult blood tests for colorectal cancer screening

J Gastroenterol. 2010 Jul;45(7):703-12. doi: 10.1007/s00535-010-0214-8. Epub 2010 Feb 17.


Background: Immunochemical tests show important advantages over chemical-based faecal occult blood tests (FOBT) for colorectal cancer (CRC) screening, but comparison studies are limited. This study was performed to compare the accuracy of a sensitive immunochemical test with the guaiac test for detecting significant neoplasia (advanced adenomas and CRC) in an average-risk population.

Methods: A random sample of 2288 asymptomatic subjects 50-79 years of age was prospectively included. Participants received three cards of the guaiac test, one sample of a latex-agglutination test (haemoglobin cut-off 50 ng/ml), and an invitation to undergo colonoscopy. Test sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated in 1756 compliers.

Results: Immunochemical and guaiac tests were positive in 143 (8.1%) and 62 (3.5%) subjects, respectively. Complete colonoscopy, performed in 402 participants (158 FOBT+ and 244 FOBT-), detected 14 (0.8%) patients with CRC and 49 (2.8%) with advanced adenomas. The immunochemical and guaiac tests for significant colorectal neoplasia showed sensitivities of 61% versus 23.8%, specificities of 95.1% versus 97.7%, PPVs of 43.4% versus 39.0%, and NPVs of 97.5% versus 95.4%, respectively. Proximal significant neoplasms were more frequently detected with the immunochemical test (85% vs. 15%) The relative risk for detecting significant neoplasia was superior in patients with a positive immunochemical test (RR 16.93; CI 7.94-36.10) than with a positive guaiac test (RR 3.34; CI 2.17-5.15).

Conclusion: A sensitive immunochemical test is markedly superior to the guaiac test for detecting significant colorectal neoplasia, and should be considered the first-choice FOBT for CRC screening in the average-risk population.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Colonoscopy
  • Colorectal Neoplasms / diagnosis*
  • Female
  • Guaiac*
  • Humans
  • Immunologic Tests / methods*
  • Male
  • Mass Screening / methods*
  • Middle Aged
  • Occult Blood
  • Predictive Value of Tests
  • Prospective Studies
  • Sensitivity and Specificity


  • Guaiac