Performance characteristics and evaluation of an automated-developed and quantitative, immunochemical, fecal occult blood screening test.

Abstract

OBJECTIVES:

Guaiac fecal occult blood colorectal cancer (CRC) screening tests (FOBT) are faulted for low sensitivity and nonspecificity for human hemoglobin (Hb). Automated-developed, immunochemical, human Hb FOBT (I-FOBT) is specific, eliminates diet restrictions, and Hb quantification allows selection of a threshold for colonoscopy. Aims were to determine 1) test reproducibility; 2) test stability; 3) intrapatient daily I-FOBT variation; 4) test sensitivity and specificity for neoplasia in 500 symptomatic/high-risk patients undergoing colonoscopy; and 5) to correlate fecal Hb measurements with findings.

METHODS:

The desktop instrument OC-Sensor (Eiken, Japan) automatically develops and quantitates 50 tests/h for Hb. Patients prepared three tests, which were quantified and then 1) repeatedly re-examined; 2) stored at 4 degrees C or 20 degrees C or 28 degrees C and repeatedly examined; and 3) fecal Hb levels were correlated with colonoscopic findings.

RESULTS:

Five I-FOBTs re-examined five times in 1 day had no significant measurement changes. Thirty tests stored for 21 or more days had a decay/day of 0.3%+/- 0.4 at 4 degrees C (NS), 2.2%+/- 1.7 at 20 degrees C (NS), and 3.7%+/- 1.8 at 28 degrees C (p < 0.05). There were intrapatient variations between the three daily I-FOBTs (NS). At the recommended 100 ng Hb/mL threshold, all six cases of CRCs and 20 out of 28 cases of advanced adenomas were detected; evaluated together their sensitivity and specificity were 76.5% and 95.3%.

CONCLUSIONS:

Desktop, automated-developed, quantitative I-FOBT is now available. Refrigerated OC-Sensor samples are stable for 21 days, easy to prepare and develop and, at the 100 ng Hb/mL threshold, have high sensitivity, specificity, and negative predictive values for significant neoplasia. Suitability for population CRC screening awaits further evaluation.

• Authors: Alex Vilkin, Paul Rozen, Zohar Levi, Amal Waked, Eran Maoz, Shlomo Birkenfeld, Yaron Niv
• Journal: The American journal of gastroenterology (Am J Gastroenterol) Vol. 100 Issue 11 Pg. 2519-25 (Nov 2005) ISSN: 0002-9270 [Print] United States
• PMID: 16279909 (Publication Type: Evaluation Study, Journal Article)

Chemical References

• Hemoglobins

Topics

• Adenoma (diagnosis)
• Adenoma, Villous (diagnosis)
• Colonic Neoplasms (diagnosis)
• Colonic Polyps (diagnosis)
• Colonoscopy
• Decision Making
• Feces (chemistry)
• Female
• Hemoglobins (analysis)
• Humans
• Immunochemistry
• Intestinal Polyps (diagnosis)
• Male
• Mass Screening (methods, standards)
• Middle Aged
• Observer Variation
• Occult Blood
• Rectal Neoplasms (diagnosis)
• Reproducibility of Results
• Risk Factors
• Sensitivity and Specificity
• Time Factors