Indirect comparison of two quantitative immunochemical faecal occult blood tests in a population with average colorectal cancer risk

Magstream and OC Sensor quantitative immunochemical faecal occult blood tests (IFOBT) have shown better performances than guaiac (G) tests in colorectal cancer screening, however Magstream and OC Sensor have never been compared. We hypothesized that similar performances could be observed with Magstream and OC Sensors, provided a similar cut-off (expressed in concentration of haemoglobin in the stools) is used. We performed a literature-based indirect comparison between these tests, taking into account the cut-off, the number of samples, and the way they were combined (I2+: at least one positive sample of 2; I2++: both positive samples; I-1: only one sample). Six studies conducted in general average-risk populations were included in this review. For each [test]*[cut-off], positivity rate (PR) decreased and predictive positive value (PPV) increased from I2+ to I-1 and I2++. For similar PR, PPV with OC Sensor was greater than with Magstream. This could be due to factors other than the test, because PPVs associated with GFOBT in studies evaluating OC Sensor were greater than PPVs associated with GFOBT in the study evaluating Magstream. Direct comparison between Magstream and OC Sensor is needed to confirm the suspected superiority of OC Sensor.