A quantitative immunochemical fecal occult blood test for colorectal neoplasia.
BACKGROUND
Guaiac-based fecal occult blood tests (FOBTs) for colorectal cancer screening are not specific for human hemoglobin and have low sensitivity. Automated-development, immunochemical FOBT is quality-controlled, is specific for human hemoglobin, and does not require diet restriction.


OBJECTIVE
To measure the sensitivity and specificity of quantitative immunochemical fecal hemoglobin measurements for detection of cancer and advanced adenoma in patients undergoing colonoscopy, to determine fecal hemoglobin thresholds that give the highest posttest probability for neoplasia, and to determine the number of immunochemical FOBTs needed.


METHODS
Prospective, cross-sectional study.


METHODS
Ambulatory endoscopy services of the main health medical organization in Tel Aviv, Israel.


METHODS
1000 consecutive ambulatory patients--some asymptomatic but at increased risk for colorectal neoplasia and some symptomatic--who were undergoing elective colonoscopy and volunteered to prepare immunochemical FOBTs.


METHODS
The hemoglobin content of 3 bowel movements was measured, and the highest value was compared with colonoscopy findings.


METHODS
Sensitivity, specificity, predictive values, likelihood ratios, and 95% CIs of fecal hemoglobin measurements for clinically significant neoplasia, their relationship to the amount of fecal hemoglobin measured, and the number of immunochemical FOBTs performed.


RESULTS
Colonoscopy identified clinically significant neoplasia in 91 patients (cancer in 17 patients and advanced adenomas in 74 patients). Using 3 immunochemical FOBTs and a hemoglobin threshold of 75 ng/mL of buffer, sensitivity and specificity were 94.1% (95% CI, 82.9% to 100.0%) and 87.5% (CI, 85.4% to 89.6%), respectively, for cancer and 67% (CI, 57.4% to 76.7%) and 91.4% (CI, 89.6% to 93.2%), respectively, for any clinically significant neoplasia.


CONCLUSIONS
The fecal sampling method is standardized, but the sample size depends on fecal consistency. Some patients were tested while discontinuing aspirin and anticoagulant therapies. Study patients were at increased risk, and results might not apply to average-risk populations.


CONCLUSIONS
Quantitative immunochemical FOBT has good sensitivity and specificity for detection of clinically significant neoplasia. Test performance in screening average-risk populations is not known.
Levi
Zohar
Z
Rabin Medical Center, Beilinson Hospital, Petach Tikva, Israel.
Rozen
Paul
P
Hazazi
Rachel
R
Vilkin
Alex
A
Waked
Amal
A
Maoz
Eran
E
Birkenfeld
Shlomo
S
Leshno
Moshe
M
Niv
Yaron
Y
D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D005243:Feces / Q000737:chemistry; D006138:Guaiac; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007120:Immunochemistry / Q000379:methods*; D007557:Israel; D016013:Likelihood Functions; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009780:Occult Blood; D011446:Prospective Studies; D012680:Sensitivity and Specificity
D006454:Hemoglobins; D006138:Guaiac