Sensitivity and Specificity of Community Fecal Immunotesting Screening for Colorectal Carcinoma in a High-Risk Canadian Population

Comparative Performance of Common Fecal Immunochemical Tests : A Cross-Sectional Study

BACKGROUND

Despite widespread use of fecal immunochemical tests (FITs) for colorectal cancer (CRC) screening, data to guide test selection are limited.

OBJECTIVE

To compare the performance characteristics of 5 commonly used FITs, using colonoscopy as the reference standard.

DESIGN

Cross-sectional study. (ClinicalTrials.gov: NCT03264898).

SETTING

Three U.S. academic medical centers and affiliated endoscopy units.

PARTICIPANTS

Patients aged 50 to 85 years undergoing screening or surveillance colonoscopy.

INTERVENTION

Participants completed 5 different FITs before their colonoscopy, including 4 qualitative tests (Hemoccult ICT, Hemosure iFOB, OC-Light S FIT, QuickVue iFOB) and 1 quantitative test (OC-Auto FIT, which was run at the manufacturer's threshold for positivity of >100 ng/mL).

MEASUREMENTS

The primary outcome was test performance (sensitivity and specificity) for each of the 5 FITs for advanced colorectal neoplasia (ACN), defined as advanced polyps or CRC. Positivity rates, positive and negative predictive values, and rates of unevaluable tests were compared. Multivariable models were used to identify factors affecting sensitivity.

RESULTS

A total of 3761 participants were enrolled, with a mean age of 62.1 years (SD, 7.8); 63.2% of participants were female, 5.7% were Black, 86.4% were White, and 28.7% were Hispanic. There were 320 participants with ACN (8.5%), including 9 with CRC (0.2%). The test positivity rate varied 4-fold (3.9% to 16.4%) across FITs. Rates of unevaluable FITs ranged from 0.2% to 2.5%. The sensitivity for ACN varied from 10.1% to 36.7%, and specificity varied from 85.5% to 96.6%. Differences in sensitivity between FITs were all statistically significantly different except between Hemosure iFOB and QuickVue iFOB, and specificity differences were all statistically significantly different from one another. In addition to FIT brand, distal location of ACN was also associated with higher FIT sensitivity.

LIMITATION

The study did not assess the programmatic sensitivity of annual FIT.

CONCLUSION

Although considered a single class, FITs have varying test performance for detecting ACN and should not be considered interchangeable.

PRIMARY FUNDING SOURCE

National Institutes of Health.

The Use of a Non-Invasive Biomarker for Colorectal Cancer Screening: A Comparative Cost-Effectiveness Modeling Study

This study aimed to examine the cost-effectiveness of fecal biomarker M3 panel compared to fecal immunochemical test (FIT) and colonoscopy in an Asian population. In a hypothetical population of 100,000 persons aged 50 years who received FIT yearly, M3 biomarker yearly, or colonoscopy every 10 years until the age of 75 years. Participants with positive FOBT or a result of "high risk" identified using the M3 biomarker are offered colonoscopy. We assumed surveillance colonoscopy is repeated every 3 years, and examined the treatment cost. A comparison of various outcome measures was conducted using Markov modelling. The incremental cost-effectiveness ratio (ICER) of FIT, M3 biomarker, and colonoscopy was USD108,176, USD133,485 and USD159,596, respectively. Comparing with FIT, the use of M3 biomarker could lead to significantly smaller total loss of cancer-related life-years (2783 vs. 5279); a higher number of CRC cases prevented (1622 vs. 146), a higher proportion of CRC cases prevented (50.2% vs. 4.5%), more life-years saved (2852 vs. 339), and cheaper total costs per life-year saved (USD212,553 vs. 773,894). The total costs per life-year saved is more affordable than that achieved by colonoscopy as a primary screening tool (USD212,553 vs. USD236,909). The findings show that M3 biomarkers may be more cost-effective than colonoscopy.

Comparative effectiveness of five fecal immunochemical tests using colonoscopy as the gold standard: study protocol

BACKGROUND

There are nearly 50,000 colorectal cancer (CRC) deaths in the United States each year. CRC is curable if detected in its early stages. Fecal immunochemical tests (FITs) can detect precursor lesions and many can be analyzed at the point-of-care (POC) in physician offices. However, there are few data to guide test selection. Broader use of FITs could make CRC screening more accessible, especially in resource-poor settings.

METHODS

A total of 3600 racially and ethnically diverse individuals aged 50 to 85 years having either a screening or surveillance colonoscopy will be recruited. Each participant will complete five FITs on a single stool sample. Test characteristics for each FIT for advanced colorectal neoplasia (ACN) will be calculated using colonoscopy as the gold standard.

RESULTS

We have complete data from a total of 2990 individuals. Thirty percent are Latino and 5.3% are black/African American. We will present full results once the study is completed.

CONCLUSIONS

Our focus in this study is how well FITs detect ACN, using colonoscopy as the gold standard. Four of the five FITs being used are POC tests. Although FITs have been shown to have acceptable performance, there is little data to guide which ones have the best test characteristics and colonoscopy is the main CRC screening test used in the United States. Use of FITs will allow broader segments of the population to access CRC screening because these tests require no preparation, are inexpensive, and can be collected in the privacy of one's home. Increasing CRC screening uptake will reduce the burden of advanced adenomas and colorectal cancer.

Which Fecal Immunochemical Test Should I Choose?

OBJECTIVES

To summarize the fecal immunochemical tests (FITs) available in the United States, the 2014 pathology proficiency testing (PT) program FIT results, and the literature related to the test characteristics of FITs available in the United States to detect advanced adenomatous polyps (AAP) and/or colorectal cancer (CRC).

METHODS

Detailed review of the Food and Drug Administration's Clinical Laboratory Improvement Amendments (CLIA) database of fecal occult blood tests, the 2014 FIT PT program results, and the literature related to FIT accuracy.

RESULTS

A search of the CLIA database identified 65 FITs, with 26 FITs available for purchase in the United States. Thirteen of these FITs were evaluated on a regular basis by PT programs, with an overall sensitivity of 99.1% and specificity of 99.2% for samples spiked with hemoglobin. Automated FITs had better sensitivity and specificity than CLIA-waived FITs for detection of AAP and CRC in human studies using colonoscopy as the gold standard.

CONCLUSION

Although many FITs are available in the United States, few have been tested in proficiency testing programs. Even fewer have data in humans on sensitivity and specificity for AAP or CRC. Our review indicates that automated FITs have the best test characteristics for AAP and CRC.

Inadequate Utilization of Diagnostic Colonoscopy Following Abnormal FIT Results in an Integrated Safety-Net System

OBJECTIVES

The effectiveness of stool-based colorectal cancer (CRC) screening is contingent on colonoscopy completion in patients with an abnormal fecal immunochemical test (FIT). Understanding system and patient factors affecting follow-up of abnormal screening tests is essential to optimize care for high-risk cohorts.

METHODS

This retrospective cohort study was conducted in an integrated safety-net system comprised of 11 primary-care clinics and one Gastroenterology referral unit and included patients 50-75 years, with a positive FIT between April 2012 and February 2015.

RESULTS

Of the 2,238 patients identified, 1,245 (55.6%) completed their colonoscopy within 1-year of the positive FIT. The median time from positive FIT to colonoscopy was 184 days (interquartile range 140-232). Of the 13% of FIT positive patients not referred to gastroenterology, 49% lacked documentation addressing their abnormal result or counseling on the increased risk of CRC. Of the patients referred but who missed their appointments, 62% lacked documentation following up on the abnormal result in the absence of a completed colonoscopy. FIT positive patients never referred to gastroenterology or who missed their appointment after referrals were more likely to have comorbid conditions and documented illicit substance use compared with patients who completed a colonoscopy.

CONCLUSIONS

Despite access to colonoscopy and a shared electronic health record system, colonoscopy completion after an abnormal FIT is inadequate within this safety-net system. Inadequate follow-up is in part explained by inappropriate screening, but there is an absence of clear documentation and systematic workflow within both primary care and GI specialty care addressing abnormal FIT results.