Nihan USAKLIGIL, Sevilay SEZER, Fatma Meric YILMAZ, Turan TURHAN
International Journal of Medical Biochemistry - 2026;9(2):103-110
Objectives: Immunochemical fecal occult blood test has been commonly used for community-based colorectal cancer screening. There is a wide variety of fecal immunochemical test (FIT) products available in the market. However, there is limited performance information for many brands, making it essential to assess and compare the performance of these FITs. Therefore, this study aims to assess the level of agreement between eight FIT products with various cut-off values (two quantitative, six qualitative) and to evaluate the analytical performance of FITs through repeatability, interference, and stability analyses. Methods: This study was conducted using a total of 313 stool specimens of which 211 specimens were obtained from randomly selected patients without any dietary restrictions, and the remainder 101 specimens were spiked with hemoglobin. The fecal occult blood results from all brands were evaluated as positive or negative. The level of agreement of FITs were assessed. Repeatability, stability and interference studies of FITs were also carried out. Results: FITs were found to have fair to almost perfect agreement with kappa values ranging from 0.28 to 0.94 (all p<0.001) in the pairwise comparisons but statistically significant differences were found among most FITs by McNemar's test with Bonferroni correction (adjusted alpha=0.0018). Repeatability and interference studies showed consistent results, but stability performance varied among FITs. Conclusion: This study showed that agreement and analytical performance among FITs vary, that statistically significant differences may be observed between some test pairs, and that agreement measures alone are not sufficient when considering test interchangeability. Test selection should be based on a comprehensive assessment that considers analytical performance together with agreement results and the potential impact on laboratory and clinical management.
