Evaluation of inter-test agreement and analytical performance of eight fecal immunochemical tests
Nihan Usakligil1, Sevilay Sezer2, Fatma Meric Yilmaz3, Turan Turhan41Medical Biochemistry Laboratory, Ankara Numune Training and Research Hospital, Ankara, Türkiye2Medical Biochemistry Laboratory, Ankara Numune Training and Research Hospital, Ankara, Türkiye; Medical Biochemistry Laboratory, Ankara Bilkent City Hospital, Ankara, Türkiye
3Medical Biochemistry Laboratory, Ankara Numune Training and Research Hospital, Ankara, Türkiye; Department of Medical Biochemistry, Ankara Yildirim Beyazıt University Faculty of Medicine, Ankara, Türkiye
4Medical Biochemistry Laboratory, Ankara Numune Training and Research Hospital, Ankara, Türkiye; Department of Medical Biochemistry, Ankara Yildirim Beyazıt University Faculty of Medicine, Ankara, Türkiye; Department of Medical Biochemistry, University of Health Sciences, Ankara Bilkent City Hospital Health Application and Research Center, Ankara, Türkiye
INTRODUCTION: 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 hemo-globin. 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 McNe-mar’s test with Bonferroni correction (adjusted α=0.0018). Repeatability and interference studies showed consistent results, but stability performance varied among FITs.
DISCUSSION AND CONCLUSION: This study showed that agreement and analytical performance among FITs vary, that statistically signifi-cant 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 ana-lytical performance together with agreement results and the potential impact on laboratory and clinical management.
Keywords: Agreement, analytical performance, fecal immunochemical test, fecal occult blood, FIT, FOB
Manuscript Language: English