Prevalence of repeat faecal immunochemical testing in symptomatic patients attending primary care

Abstract

Aim:The faecal immunochemical test (FIT) for faecal haemoglobin (f-Hb) helps determine the risk of colorectal cancer (CRC) and has been integrated into symptomatic referral pathways. 'Safety netting' advice includes considering referral for persistent symptoms, but no published data exists on repeated FITs. We aimed to examine the prevalence of serial FITs in primary care and CRC risk in these patients.Method: A multicentre, retrospective, observational study was conducted of patients with two or more consecutive f-Hb results within a year from three Scottish Health Boards which utilize FIT in primary care. Cancer registry data ensured identification of CRC cases.Results: Overall, 135 396 FIT results were reviewed, of which 12 359 were serial results reported within 12 months (9.1%), derived from 5761 patients. Of these, 42 (0.7%) were diagnosed with CRC. A total of 3487 (60.5%) patients had two f-Hb < 10 μg/g, 944 (16.4%) had f-Hb ≥ 10 μg/g followed by <10 μg/g, 704 (12.2%) f-Hb < 10 μg/g followed by ≥10 μg/g and 626 (10.9%) had two f-Hb ≥ 10 μg/g. The CRC rate in each group was 0.1%, 0.4%, 1.4% and 4.0%, respectively. Seven hundred and thirty four patients submitted more than two FITs within a year. The likelihood of one or more f-Hb ≥ 10 μg/g rose from 40.4% with two samples to 100% with six, while the CRC rate fell from 0.8% to 0%. Conclusion:Serial FITs within a year account for 9.1% of all results in our Boards. CRC prevalence amongst symptomatic patients with serial FIT is lower than in single-FIT cohorts. Performing two FITs within a year for patients with persistent symptoms effectively acts as a safety net, while performing more than two within this timeframe is unlikely to be beneficial.

Real-world data evaluating Guy’s rapid diagnostic clinic as an alternate pathway for patients with FIT levels below 10

“…Furthermore, various studies have investigated the benefits of repeated FIT testing 22. For instance, a recent cohort study looking at 5761 patients concluded that a second negative test within 12 months of the first sample, in the context of ongoing clinical concern reliably rules out CRC 23. However, BSG/ACPGBI recommendations concluded that there is currently insufficient evidence to recommend the use of a repeat FIT to guide referrals in routine practice 8.…”

Understanding colorectal cancer risk for symptomatic patients in primary care: A cohort study utilising faecal immunochemical tests and blood results in England

“…However, these tools have used different combinations across the full range of fHb results—it is unlikely that any marker will add to the value of high fHb (≥100 μg Hb/g faeces or similar). Reduction of missed CRC below any threshold for urgent referral, based on an FIT result alone or in combination with other markers, may be improved by repeat testing 24,25 . We have not included the repeat‐tested group in our analysis.…”

“…Reduction of missed CRC below any threshold for urgent referral, based on an FIT result alone or in combination with other markers, may be improved by repeat testing. 24,25 We have not included the repeat-tested group in our analysis. Although further work is required to validate this approach the 'cost'-financial and otherwise of a missed CRC is much higher than that of a repeat FIT.…”

Do risk scores improve use of faecal immunochemical testing for haemoglobin in symptomatic patients in primary care?

“…Sensitivity for CRC improves with a two FIT strategy where referral for bowel visualization is made when at least one FIT result is ≥10 μg Hb/g [27,28], although at the expense of a higher positivity. Further existing literature on repeat FIT strategies show two FIT results <10 μg Hb/g as an effective safety net for CRC [29,30]. However, a systematic review has concluded that the existing literature is conflicting and minimal [31].…”