Laboratory Medicine ›› 2019, Vol. 34 ›› Issue (2): 152-158.DOI: 10.3969/j.issn.1673-8640.2019.02.013

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Performance evaluation of 17 fecal immunochemical tests

LI Pei1, ZHU Peichao2, SONG Rongwei1, TAO Sha1   

  1. 1. Department of Public Health,Fudan University,Shanghai 200032,China
    2. Shanghai Center for Clinical Laboratory,Shanghai 200126,China
  • Received:2017-12-21 Online:2019-02-28 Published:2019-02-28

Abstract:

Objective To investigate the reasons for high false positive rate of fecal immunochemical tests (FIT) through evaluating the performance of 17 common FIT. Methods Simulated feces samples with 14 different levels were prepared. Totally,7 laboratory assistants tested these samples by 15 qualitative FIT(No.1-No.15)and 2 quantitative FIT(No.16 and No.17). The results were recorded. A total of 2 automatic FIT analyzers,Luminex200 system and OC-Sensor,were used as well. Results A total of 1 666 samples were tested. The positive rate of 11 qualitative FIT was higher than theoretical positive rate(P<0.005). There was no statistical significance between the positive rate of 2 quantitative FIT and theoretical positive rate(P16=0.43,P17=0.21). There was a correlation between theoretical concentration and the hemoglobin levels tested by the 2 quantitative FIT(r16=0.88,P<0.000 1;r17=0.92,P<0.000 1). The sensitivities of qualitative FIT reached 100.00%,and the Kappa values of 11 qualitative FIT were <0.40. The sensitivities of 2 quantitative FIT(No.16 and No.17) were 86.21%,and the specificities were 88.24% and 97.06%,respectively,and the Kappa values were 0.73 and 0.80,respectively.Conclusions The qualitative FIT are cheap and convenient,but the quantity of feces samples and diluents are not standardized well,and the actual cut-off values are lower than given cut-off values,which can lead to the low specificity of qualitative FIT. The cost of quantitative FIT was high,they are not affected by subjective judgment,and the specificity is relatively high.

Key words: Fecal immunochemical test, Colorectal cancer, Cut-off value, Sensitivity, Specificity

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