Comparison of FIT Tests

November 7, 2024

Written by Peter Liu

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Commonly used fecal immunochemical tests (FIT) tests have significant differences in test performance.

Synopsis
This cross-sectional study evaluated the performance of five FITs for detecting advanced colorectal neoplasia (ACN) among 3,761 participants undergoing colonoscopy. The results indicated significant variability among the tests: sensitivity ranged from 10.1% (Hemoccult ICT) to 36.7% (OC-Light S FIT), and specificity from 85.5% (OC-Light S FIT) to 96.6% (Hemoccult ICT). The OC-Auto FIT had the highest positive predictive value (28.9%) and positive likelihood ratio. All differences in sensitivity and specificity were statistically significant, emphasizing that FITs should not be considered interchangeable due to their differing diagnostic accuracy profiles. [AI-generated]

Consider fitting the FIT to the sitch 
Patients have several options for colorectal cancer screening, including colonoscopy, FIT, FIT with multi-target DNA testing, and CT colonoscopy. Colonoscopy is generally preferred due to its superior test performance and ability to remove precancerous lesions. However, for patients who cannot or prefer not to undergo colonoscopy, annual FIT testing is a common alternative. Clinicians often do not consider the specific type of FIT used, but this study highlights the importance of selecting the appropriate test. For patients with limited access to colonoscopy or who are treatment-resistant, using a FIT with high specificity, like the OC-Auto FIT, can reduce unnecessary colonoscopies. Conversely, when access to colonoscopy is readily available or when avoiding a missed cancer diagnosis is critical, a high-sensitivity FIT is preferable, though direct colonoscopy may still be best. Additionally, distinguishing between qualitative and quantitative FITs is important, as quantitative tests provide more detailed results, which can inform clinical decision-making based on the positivity level. This nuanced approach to FIT selection may better align with patient preferences and healthcare resources.

Source 
Comparative Performance of Common Fecal Immunochemical Tests : A Cross-Sectional Study. Ann Intern Med. 2024 Oct;177(10):1350-1360. doi: 10.7326/M24-0080. Epub 2024 Sep 3. PMID: 39222513