Original Contribution
The American Journal of Gastroenterology (2005) 100, 2519–2525; doi:10.1111/j.1572-0241.2005.00231.x
Performance Characteristics and Evaluation of an Automated-Developed and Quantitative, Immunochemical, Fecal Occult Blood Screening Test
Alex Vilkin MD1, Paul Rozen MB, BS1,2, Zohar Levi MD1, Amal Waked BSc1, Eran Maoz MD3, Shlomo Birkenfeld MD3 and Yaron Niv MD1,2
- 1Gastroenterology Department, Rabin Medical Center, Beilinson Hospital, Petach Tikva;
- 2Tel Aviv University Medical School, Tel Aviv, Israel;
- 3Gastroenterology Units, Clalit Health Services, Tel Aviv, Israel
Correspondence: Prof. Paul Rozen, Department of Gastroenterology, Tel Aviv Medical Center, 6 Weizmann Street, Tel Aviv 64239, Israel
Received 31 March 2005; Revised 0000; Accepted 28 May 2005.
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°C or 20°C or 28°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°C (NS), 2.2% 1.7 at 20°C (NS), and 3.7% 1.8 at 28°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.
