Faecal immunochemical tests (FIT) can help to rule out colorectal cancer in patients presenting in primary care with lower abdominal symptoms: a systematic review conducted to inform new NICE DG30 diagnostic guidance

Abstract

Background: This study has attempted to assess the effectiveness of quantitative faecal immunochemical tests (FIT) for triage of people presenting with lower abdominal symptoms, where a referral to secondary care for investigation of suspected colorectal cancer (CRC) is being considered, particularly when the 2-week criteria are not met.

Methods: We conducted a systematic review following published guidelines for systematic reviews of diagnostic tests. Twenty-one resources were searched up until March 2016. Summary estimates were calculated using a bivariate model or a random-effects logistic regression model.

Results: Nine studies are included in this review. One additional study, included in our systematic review, was provided as 'academic in confidence' and cannot be described herein. When FIT was based on a single faecal sample and a cut-off of 10 μg Hb/g faeces, sensitivity estimates indicated that a negative result using either the OC-Sensor or HM-JACKarc may be adequate to rule out nearly all CRC; the summary estimate of sensitivity for the OC-Sensor was 92.1% (95% confidence interval, CI 86.9-95.3%), based on four studies (n = 4091 participants, 176 with CRC), and the only study of HM-JACKarc to assess the 10 μg Hb/g faeces cut-off (n = 507 participants, 11 with CRC) reported a sensitivity of 100% (95% CI 71.5-100%). The corresponding specificity estimates were 85.8% (95% CI 78.3-91.0%) and 76.6% (95% CI 72.6-80.3%), respectively. When the diagnostic criterion was changed to include lower grades of neoplasia, i.e. the target condition included higher risk adenoma (HRA) as well as CRC, the rule-out performance of both FIT assays was reduced.

Conclusions: There is evidence to suggest that triage using FIT at a cut-off around 10 μg Hb/g faeces has the potential to correctly rule out CRC and avoid colonoscopy in 75-80% of symptomatic patients.

Systematic review registration: PROSPERO 42016037723.

Fig. 1

Flow of studies through the review process

Fig. 2

ROC space plot for the OC-Sensor assay using different faecal haemoglobin cut-offs for the target condition of CRC

Fig. 3

HSROC for the OC-Sensor assay using a 10 μg Hb/g faeces cut-off and a single sample (four studies)

Fig. 4

Testing outcomes for a hypothetical cohort of 1000 patients using OC-Sensor at the 10 μg Hb/g faeces threshold, for the target condition a CRC and b AN

Fig. 5

Testing outcomes for a hypothetical cohort of 1000 patients using HM-JACKarc at the 10 μg Hb/g faeces threshold, for the target condition a CRC and b AN