Evaluation of a desk top instrument for the automated development and immunochemical quantification of fecal occult blood.
BACKGROUND
The guaiac fecal occult blood test (FOBT) for colorectal cancer (CRC) screening is user dependent and not specific for human hemoglobin (Hb). The automated-developed, quantitative, immunochemical human Hb FOBT (I-FOBT) is specific, allows for quality control and selection of a suitable Hb level, with optimal sensitivity and specificity, for colonoscopy.


METHODS
We evaluated a desktop instrument, OC-MICRO (Eiken, Japan), which automatically develops and quantifies 50 fecal tests/hr for Hb; for ease of use, test reproducibility and stability and intra-patient daily I-FOBT variation; clinical evaluation included sensitivity and specificity for neoplasia in patients undergoing colonoscopy.


RESULTS
Five hundred patients prepared 3 fecal tests which were quantified for Hb, I-FOBT samples were: (1) repeatedly re-examined; (2) stored at 4 degrees C or 20 degrees C or 28 degrees C and re-examined; (3) I-FOBT levels correlated with colonoscopic findings. Five I-FOBTs re-examined 6 times had no significant changes; 30 tests stored > or = 21 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). Receiver operator characteristic curve analysis showed that at the 100 ng Hb/mL I-FOBT level 76.5% of CRCs and advanced adenomas were detected with a specificity of 95.3%.


CONCLUSIONS
The instrument provided reproducible results and refrigerated I-FOBT samples were stable 21 days. An I-FOBT level can be chosen to provide optimal sensitivity and specificity for significant neoplasia.
Rozen
Paul
P
Department of Gastroenterology, Rabin Medical Center, Beilinson Hospital, Petach Tikva, Israel. rozen@tasmc.health.gov.il
Waked
Amal
A
Vilkin
Alex
A
Levi
Zohar
Z
Niv
Yaron
Y
D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D001330:Electronic Data Processing / Q000295:instrumentation; D006801:Humans; D007120:Immunochemistry / Q000295:instrumentation*; D009780:Occult Blood; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity