Diagnostic accuracy of faecal occult blood tests used in screening for colorectal cancer: a systematic review

Objective To determine the accuracy of guaiac and immunochemical faecal occult blood tests (FOBTs) for the detection of colorectal cancer in an average-risk screening population. Methods Fifteen electronic databases, the internet, key journals and reference lists of included studies were searched. We included diagnostic accuracy studies that compared guaiac or immunochemical FOBTs with any reference standard, for the detection of colorectal cancer in an average-risk adult population, with sufficient data to construct a 2 x 2 table. Results Fifty-nine studies were included. Thirty-three evaluated guaiac FOBTs, 35 immunochemical FOBTs and one evaluated sequential FOBTs. Sensitivities for the detection of all neoplasms ranged from 6.2% (specificity 98.0%) to 83.3% (specificity 98.4%) for guaiac FOBTs, and 5.4% (specificity 98.5%) to 62.6% (specificity 94.3%) for immunochemical FOBTs. Specificity ranged from 65.0% (sensitivity 44.1%) to 99.0% (sensitivity 19.3%) for guaiac FOBTs, and 89.4% (sensitivity 30.3%) to 98.5% (sensitivity 5.4%) for immunochemical FOBTs. Diagnostic case-control studies generally reported higher sensitivities. Sensitivities were higher for the detection of CRC, and lower for adenomas, in both the diagnostic cohort and diagnostic case-control studies for both guaiac and immunochernical FOBTs. Conclusions Immudia HemSp appeared to be the most accurate immunochemical FOBT, however, there was no clear evidence to suggest whether guaiac or immunochemical FOBTs performed better, either from direct or indirect comparisons. Poor reporting of data limited the scope of this review, and the use the Standards for Reporting of Diagnostic Accuracy guidelines is recommended for reporting future diagnostic accuracy studies.