Word count (abstract): 358 Word count (manuscript): 3771 Number of tables: 1 ABSTRACT Background: Studies report inconsistent performance characteristics of fecal immunochemical tests (FITs) for both colorectal cancer (CRC) and advanced adenomas.Purpose: To summarize test characteristics of fecal immunochemical tests (FITs) for CRC and advanced adenomas in average-risk persons undergoing screening colonoscopy (reference standard) and identify factors affecting these characteristics.Data Sources: Ovid MEDLINE, PubMed, Embase, and the Cochrane Library from database inception through October 2018; reference lists of studies and reviews.
Study Selection:Two reviewers independently screened records to identify published Englishlanguage prospective or retrospective observational studies that evaluated FIT sensitivity and specificity for colonoscopy findings in asymptomatic average-risk adults.Data Extraction: Two authors independently extracted study data and evaluated study quality.
Data Synthesis:We included 31 studies (120,255 participants, 17 FITs), all of which we judged had low-to-moderate risk for bias. Performance characteristics depended on the threshold for a positive test. A test threshold of 10 µg/g feces resulted in a CRC sensitivity of 0.91 (95% CI, 0.84 to 0.95) and negative likelihood ratio of 0.10 (CI, 0.06 to 0.19), while a threshold of > 20 µg/g resulted in CRC specificity of 0.95 (CI, 0.94 to 0.96) and positive likelihood ratio of 15.49 (CI, 9.82 to 22.39). Advanced adenoma sensitivity was 0.40 (CI, 0.33 to 0.47) and negative likelihood ratio was 0.67 (CI, 0.57 to 0.78) at 10 µg/g, while specificity was 0.95 (0.94 to 0.96) and positive likelihood ratio was 5.86 (CI, 3.77-8.97) at > 20 µg/g. There was low-to high heterogeneity among studies, depending on threshold. While several FITs had adequate test performance, CRC sensitivity and specificity for one qualitative FIT were 90% and 91%, respectively, at its single threshold of 10 µg/g, with positive and negative likelihood ratios of 10.13 and 0.11, respectively. Comparison of performance of 3 FITs at 3 thresholds was inconclusive: CIs overlapped and the comparisons were across, rather than within, studies.
Limitations:Only English-language studies were included; incomplete reporting limited quality assessment of some evidence. Test characteristics are for one-time, rather than for serial, testing.
Conclusion:Single-application FITs have moderate-to-high CRC sensitivity and specificity depending on the positivity threshold. Sensitivity of one-time testing for advanced adenomas is low regardless of threshold.
BACKGROUNDColorectal cancer (CRC) is a leading cause of death among digestive diseases and the second leading cause of cancer related death in the United States (1). Despite the effectiveness and cost-effectiveness of screening (2-4), just 60-65% of the screen-eligible population is current with screening (5), a rate that has fallen short of the targeted goal of 80% by 2018 (2, 5, 6). To some extent, this shortcoming represents concern over the be...