The Effect of the Variability in Fecal Immunochemical Test Sample Collection Technique on Clinical Performance

Abstract

Background: Fecal immunochemical test (FIT) performance can be affected by post-collection variables. Collection technique might also affect fecal hemoglobin concentration (f-Hb). Variation in quantity of feces collected in samples returned in a colorectal cancer detection program, and the effects of under-sampling, were assessed.Methods: Collection devices obtained from patients undergoing FIT were assessed for the color (in five classes) of the feces in buffer, mass, and f-Hb. Associations between these were examined in an in vitro study on Hb-spiked feces. Variables possibly associated with under-sampling were investigated using multivariable logistic regression. The effect of low sample mass on clinical performance (false-negative results) was determined.Results: Of 6,898 samples collected by 3,449 individuals (46.9% male, median age: 65.3 years), the buffer was lightest in color in 362 (5.2%), and darkest in 420 (6.1%). Samples with the lightest color had a significantly lower f-Hb compared with all darker classes (P < 0.001). Mass was recorded for 650 devices: The lightest colored samples had significantly lower mass (P < 0.05). The correlation between mass and f-Hb was confirmed in vitro (r ¼ 0.897, P < 0.001). Low mass was not associated with age, sex, or technical factors (P > 0.05). Under-sampling related to the lightest color was not associated with false-negative results for colorectal cancer and advanced adenoma, but was for all neoplasia and inflammatory bowel disease.Conclusions: Wide variation existed in the amount of feces collected. Under-sampling results in lower measured f-Hb and may increase false-negative results.Impact: Color of sample buffer could be used to identify inadequate sampling.

Faecal immunochemical test mitigates risk of delayed colonoscopy in people with elevated risk of colorectal neoplasia

“…As part of the SCOOP program, 15 if an interval FIT returned a positive result, the next colonoscopy was completed sooner than scheduled, while those returning a negative FIT had colonoscopies performed as scheduled. Complete details about the faecal tests have been previously published 16 …”

Quality Improvement of Sample Collection Increases the Diagnostic Accuracy of Quantitative Fecal Immunochemical Test in Colorectal Cancer Screening: A Pilot Study

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